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I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Well it sorta comparing apples to oranges. It all depend ft/lbs torque the engine are rated for. Manufactures can limit ft/lbs torque on larger engines and a smaller engine might have the same power so you must know the current engine's specs and compare to the possible replacement specs.

https://www.smallenginesurplus.com/

Also a dull blade will cause cutting problems.

Start in on it with yer string trimmer.. Then clean up with the push mow.

StarTech said:

Well it sorta comparing apples to oranges. It all depend ft/lbs torque the engine are rated for. Manufactures can limit ft/lbs torque on larger engines and a smaller engine might have the same power so you must know the current engine's specs and compare to the possible replacement specs.

https://www.smallenginesurplus.com/

Also a dull blade will cause cutting problems.

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Thanks! The 140cc one is 5.5ft-lbs. Apparently the Honda ($550 model) is 8.2.

Does 8ft lbs sound like enough for tall grass?

7394 said:

Start in on it with yer string trimmer.. Then clean up with the push mow.

Click to expand...

Nope. That made it worse. Then I tried mowing it, and it was worse, if anything. Definitely not better.

Simple. Don't let your grass get that tall. Mow often with a properly working mower. The rule-of-thumb is to cut no more than 1/3 the length of the grass. So if you want your grass at 2", mow when it gets to 3". In the growing season, that's usually around once a week. Make sure the deck is not clogged with grass. Once a year, clean out the deck of dried, caked-on grass. Twice a year, sharpen the blade, and check the air filter. Blow out the air filter with compressed air if it's not wet with gas or oil. Replace if it is. Use side discharge. Mulching only works well on well maintained (short) grass.

A properly working mower has no problem cutting through properly maintained grass. This is a better, easier, and cheaper option than an engine swap. Your grass will look much better too, and your yard won't become a habitat for snakes and other unwanted critters.

For mowing through super tall grass, I would set your mower to its max height, and mow. Tomorrow or the next day, lower your mower a couple of notches, and mow again. Repeat this until you get the grass at the height you need it. Then keep it mowed.

Pay someone to mow it this time with equipment rated for that type of mowing . Now you know this isn't a enjinerreng site and the answer you be looking for may not be available .

GearHead36 said:

Simple. Don't let your grass get that tall. Mow often with a properly working mower. The rule-of-thumb is to cut no more than 1/3 the length of the grass. So if you want your grass at 2", mow when it gets to 3". In the growing season, that's usually around once a week. Make sure the deck is not clogged with grass. Once a year, clean out the deck of dried, caked-on grass. Twice a year, sharpen the blade, and check the air filter. Blow out the air filter with compressed air if it's not wet with gas or oil. Replace if it is. Use side discharge. Mulching only works well on well maintained (short) grass.

A properly working mower has no problem cutting through properly maintained grass. This is a better, easier, and cheaper option than an engine swap. Your grass will look much better too, and your yard won't become a habitat for snakes and other unwanted critters.

For mowing through super tall grass, I would set your mower to its max height, and mow. Tomorrow or the next day, lower your mower a couple of notches, and mow again. Repeat this until you get the grass at the height you need it. Then keep it mowed.

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Obviously, if I mowed it before this, it would be as much of an issue. I was asking about how engine size affects power.

I agree that cutting it regularly is better. The problem is that I wasn't able to mow it earlier because of other circumstances.

As for it getting moved, its done now. I mowed professionally for years, but I just had a honda, which isn't really an option now. Someone gave me a craftsman, but it's underpowered for this, and clogs all the time (side chute, mulch, even opening the rear chute only worked if it was fully open.) I was trying to get information on what mowers would be worth buying based on actual power, and not just a random number, or as much as that's possible.

SeniorCitizen said:

Pay someone to mow it this time with equipment rated for that type of mowing . Now you know this isn't a enjinerreng site and the answer you be looking for may not be available .

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Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL

Little Fish said:

Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL

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You are talking about the difference of about 1 horsepower either way. So no big difference.

Raise cutting height to maximum and double cut it at opposite patterns.

Tiger Small Engine said:

You are talking about the difference of about 1 horsepower either way. So no big difference.

Raise cutting height to maximum and double cut it at opposite patterns.

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That's what I am planning to do. I'm letting the grass lift up a bit because it was pretty wet the other day when I mowed (no choice on that).

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

Little Fish said:

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

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For OPE, it really doesn't matter. Both are measures of the ability to cut grass. More HP = better ability to cut. More torque = better ability to cut. The problem comes when you try to compare engines rated in HP vs those rated in torque. Torque is probably a better measure, as it's easier to fudge HP numbers. If you increase RPMs by, say, 1000, the HP will increase, but that does nothing for cutting grass, which is done at a set RPM. Torque curves are flatter than HP curves, so increasing RPMs by 1000 won't result in the same torque increase as you'd get with HP. And, I think, engines are now rated in torque at a specific RPM, so comparing engines is easier.

But really, if cutting super-tall wet grass is what you want to do, a 21" Craftsman with a bigger engine is not the answer. You need something commercial.

GearHead36 said:

For OPE, it really doesn't matter. Both are measures of the ability to cut grass. More HP = better ability to cut. More torque = better ability to cut. The problem comes when you try to compare engines rated in HP vs those rated in torque. Torque is probably a better measure, as it's easier to fudge HP numbers. If you increase RPMs by, say, 1000, the HP will increase, but that does nothing for cutting grass, which is done at a set RPM. Torque curves are flatter than HP curves, so increasing RPMs by 1000 won't result in the same torque increase as you'd get with HP. And, I think, engines are now rated in torque at a specific RPM, so comparing engines is easier.

But really, if cutting super-tall wet grass is what you want to do, a 21" Craftsman with a bigger engine is not the answer. You need something commercial.

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Yeah, that makes sense (and I know HP is fudged all the time based on my shop vac purchases LOL).

Any recommendations on a relatively cheap commercial walk behind? I know cheap doesn't exist, but the Toro time master isn't even worth $500 imo, since it just clogs immediately by all accounts

The Toro Recycler needs to be upgraded a little to a Super Recycler by adding the accelerator blade as to increase the air flow for wet grass. But I have gotten a chance to the clearance for the added blade. Darn customer brought a $450 Recycler and just plain gave it away less than a week later. Boy it take some time to get in parts just to try a mod a times.

The problem is the blade used just don't have enough air lift to bag properly.

Little Fish said:

That's what I am planning to do. I'm letting the grass lift up a bit because it was pretty wet the other day when I mowed (no choice on that).

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

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Without torque, HP means nothing. And you are getting hung up over numbers for the most part don't vary enough to be able to make a difference. And a third factor that can eat up any additional torque, or HP produced by the engine. And that is air flow dynamics of the deck, blade interaction.

ILENGINE said:

Without torque, HP means nothing. And you are getting hung up over numbers for the most part don't vary enough to be able to make a difference. And a third factor that can eat up any additional torque, or HP produced by the engine. And that is air flow dynamics of the deck, blade interaction.

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Yeah, I could see that with this mower. The engine has "enough" power, but only if the cut grass is evacuated fast. Like out the bag chute. But the only way to not have it clog the blade and stall is if the bagger chute is completely open ans spraying me with grass.

The key takeaway for me is torque. I know I'll sound like Tim from Home Improvement when I say it, but it needs MORE POWER! (Ugh ugh snort)

If I put a 15HP 10 or 12ft-lb engine on there, it won't care if the deck or Gras is clogged and I can put a better blade on it (like the Oregon g5 mulching blade). It would cut better, and could handle taller grass. The issue is finding a vertical shaft engine that has enough torque to do that.

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

I think you need to step back and think a little more clearly.

1. Your current push mower worked fine for your purposes (presumably),
2. until you let your lawn get overgrown, then it gave you problems,
3. leading you to believe that the mower engine is anemic,
4. now you want to replace the engine to get more power.

The fact is, push/walk-behind mowers are not made for overgrown mowing. You can upgrade to a 170cc engine with more torque but you'll still have the same issues in the same situation as any extra "power" will still be anemic for overgrown mowing with a push mower. You are basically overreacting based on one incident, which may not happen again. But even if it does happen again, there is a solution that actually works if using a push mower for overgrown lawns....

Step 1. Raise your cutting height
Step 2. Bag the clippings as you mow
Step 3. Lower the height and mow again, preferably bagging again.

You took the hard way out by using the back-and-forth method. While bagging and mowing twice sounds like the hard way out, mowing 2ft, then backing-up 3ft, then moving forward slowly is the actual hard way out. In fact, you likely spent the same amount of time (if not more) and exerted more effort than using my solution above.

In the future, if you are going to (or have to) continue using a push mower (no shame, I mow about 15 lots with a push mower), the solution going forward is not to change the engine, rather...

1. Don't let your lawn overgrow past the point of a push mower's usability
or
2. If you do let it overgrow (for whatever reason, not judging you), use the solution above.

Little Fish said:

Yeah, I could see that with this mower. The engine has "enough" power, but only if the cut grass is evacuated fast. Like out the bag chute. But the only way to not have it clog the blade and stall is if the bagger chute is completely open ans spraying me with grass.

The key takeaway for me is torque. I know I'll sound like Tim from Home Improvement when I say it, but it needs MORE POWER! (Ugh ugh snort)

If I put a 15HP 10 or 12ft-lb engine on there, it won't care if the deck or Gras is clogged and I can put a better blade on it (like the Oregon g5 mulching blade). It would cut better, and could handle taller grass. The issue is finding a vertical shaft engine that has enough torque to do that.

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More HP or Torque and a better blade may not cut any better than your have now. I have a 72" mower connected to a 45 HP 4 cylinder diesel. And if the grass is more than 6 inches high I have to slow to about 2 mph or mow it twice with it.

So you want to be able to mow super-tall wet grass, and bag it? With a Craftsman 21" push mower? Now I'm thinking this is a troll. This job is in the territory of $10000 stand-on mowers. How long would it take to fill a bag while mowing super-tall wet grass? I'm thinking about a minute. So you'd be spending more time emptying the bag than you would be mowing.

If this is not a troll, then you seem intent on spending a lot of energy just to avoid mowing at regular intervals. Energy that could better invested in, say, mowing at regular intervals.

Still, in the Tim Taylor vein... overpowering a small push mower could be a fun project. Just don't be surprised when this thing won't do the job you're hoping it will do. As much as we like to rag on mfrs and design engineers here, they DO kinda know what they're doing. They don't put 5HP engines on 60" ZTRs, and they don't put 20HP engines on 21" push mowers. Bigger, tougher jobs that require more power also require more in other areas, like deck size and design, blades, drive systems, etc. The deck on your 21" Craftsman isn't designed to flow the amount of grass you're wanting it to. And nothing, short of commercial, is going to do well with tall wet grass. I have an entry level commercial ZTR with a 27HP engine, and I won't mow if the grass is tall and wet.

Does your mower have side discharge? If it does, I suggest discharging away from the uncut grass, and mowing 6" strips at a time. Your deck might be able to handle that amount of grass.

GearHead36 said:

So you want to be able to mow super-tall wet grass, and bag it? With a Craftsman 21" push mower? Now I'm thinking this is a troll. This job is in the territory of $10000 stand-on mowers. How long would it take to fill a bag while mowing super-tall wet grass? I'm thinking about a minute. So you'd be spending more time emptying the bag than you would be mowing.

If this is not a troll, then you seem intent on spending a lot of energy just to avoid mowing at regular intervals. Energy that could better invested in, say, mowing at regular intervals.

Still, in the Tim Taylor vein... overpowering a small push mower could be a fun project. Just don't be surprised when this thing won't do the job you're hoping it will do. As much as we like to rag on mfrs and design engineers here, they DO kinda know what they're doing. They don't put 5HP engines on 60" ZTRs, and they don't put 20HP engines on 21" push mowers. Bigger, tougher jobs that require more power also require more in other areas, like deck size and design, blades, drive systems, etc. The deck on your 21" Craftsman isn't designed to flow the amount of grass you're wanting it to. And nothing, short of commercial, is going to do well with tall wet grass. I have an entry level commercial ZTR with a 27HP engine, and I won't mow if the grass is tall and wet.

Does your mower have side discharge? If it does, I suggest discharging away from the uncut grass, and mowing 6" strips at a time. Your deck might be able to handle that amount of grass.

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I don't want to bag. I never said anything about a bag, other than the bag chute had to be open. (I don't own a bag, so grass was just flying). No, it's not safe. No, I didn't like that solution. I did that because I had to.

I came here to ask what engine size I would need to do the job. I got the answer (a commercial mower). I don't plan on leaving the grass that long again, but my area has been getting rain once a week anyway, and my lawn is ALWAYS wet (I'm talking almost clumping to shoes wet) and I don't water it. It just gets rain, and apparently there's an underground spring under my back yard.

What brands should I be looking at for a prosumer mower? Would a lawn tractor be able to do anything? (And if I got a cheapo one, would any random horizontal shaft engine work? Or would I need to match hole patterns ans things? (I'm handy, but have no welding equipment)

How big of a lawn are we talking here? I have 3 neighbors that have lawns about 50'x75' and they use riding mowers. It takes them longer to mow than it would on foot lol. But I guess it makes them feel like "a man"? That's the only reason I can figure.

You mentioned the bag chute, which, I assumed, you wouldn't be using or even mentioning if you were side discharging.

Sucks to always have wet grass.

Years ago, I had a 20" Murray mower with a Briggs engine rated at 3.5HP. This may be what's on your Craftsman. It was side discharge only, and did fine if the grass wasn't too tall. Newer mowers (less than 20 yrs old) are generally more powerful than older ones. My current push mower is a Toro Recycler with a 190cc Briggs flathead, which is considerably larger and more powerful than that 3.5HP Briggs. I try to never mow wet grass, but I have mowed grass that was WAY too tall with the Toro. With sharp blades, and the mower set up for side discharging, it had zero problems with dry grass. I don't mow if the yard is wet, but sometimes I will encounter wet spots, and in those spots the Toro would struggle, and I would have to slow way down, or mow narrow strips.

Swapping engines for a homeowner is not easy. For a shop that has a huge pile of junk/spare parts, it's much easier. I'd find a local flipper (you know, the place with 20 mowers sitting out front, all used), and see what they had. Tell him your needs, and let him suggest something for you. If this flipper is selling it, then that means that; it is repairable, it is worth repairing, and he can repair it. It will be cheaper than anything new, and probably last longer. If you don't try to mow tall wet grass, you don't need commercial. I suggest something with side discharge, which will flow grass much better than mulching or bagging. My philosophy is, buy a better (I hope) piece of equipment, but keep the old one. Find out which one works better, and then sell the other one. Repeat until I'm happy with the results.

Sounds like your Craftsman is a working mower that could be sold for actual money. After an engine swap (that may or may not go well), that could change. In the automotive world, project cars often get sold at scrap prices. A project mower generally has to be given away or thrown away. In the long run, it is usually cheaper to buy what fits your needs, and sell what doesn't, as opposed to modifying what you have. Modified equipment is usually worth less than unmodified.

Chuckers said:

How big of a lawn are we talking here? I have 3 neighbors that have lawns about 50'x75' and they use riding mowers. It takes them longer to mow than it would on foot lol. But I guess it makes them feel like "a man"? That's the only reason I can figure.

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About 60x80 and the front 50x30. Only reasons I can think they would take longer than a walk behind is they are underpowered, slow, or the yards have a lot of obstacles.

And the difference is that I would be able to sit and enjoy the breeze, as opposed to walk all over and push something while suffocating in 100% humidity LOL (at least that's the idea).

Chuckers said:

How big of a lawn are we talking here? I have 3 neighbors that have lawns about 50'x75' and they use riding mowers. It takes them longer to mow than it would on foot lol. But I guess it makes them feel like "a man"? That's the only reason I can figure.

Click to expand...

On the small subdivision yards I've had, I've always used push mowers. But... I can't say I wasn't tempted to get a rider. They are faster and often have headlights, which would allow me to get the mowing done starting at 6:00 in Sept, where I wouldn't have time to get done before dark with a push mower. I never went with a rider because of the space required to store one. I also had neighbors who I thought were stupid for having riders, as they never took advantage of the mower's ability to get the mowing done in the evening in the Fall. They would only mow on sunny Saturday afternoons, apparently so that the most people could see their fancy (usually green) mower. I had one neighbor who I couldn't fault for his decision to get a rider. His mower purchase resulted in his wife doing all the mowing.

Little Fish said:

Would a lawn tractor be able to do anything? (And if I got a cheapo one, would any random horizontal shaft engine work? Or would I need to match hole patterns ans things? (I'm handy, but have no welding equipment)

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Somehow I missed this. Cheapo lawn tractors tend to mow better than cheapo push mowers. I used to have a riding mower with a 36" or 38" deck (it's been a long time) and 12HP engine. It mowed better than my Toro Recycler. It was almost useless on the hills in my yard, so I got rid of it, but it impressed me that it mowed as well as it did with only 12HP. That could be due to most push mowers having the engine speed set too low.

Getting a lawn tractor, IMO, is a much better idea than an engine swap on a push mower.

BTW, almost all mower engines are vertical shaft.

GearHead36 said:

On the small subdivision yards I've had, I've always used push mowers. But... I can't say I wasn't tempted to get a rider. They are faster and often have headlights, which would allow me to get the mowing done starting at 6:00 in Sept, where I wouldn't have time to get done before dark with a push mower. I never went with a rider because of the space required to store one. I also had neighbors who I thought were stupid for having riders, as they never took advantage of the mower's ability to get the mowing done in the evening in the Fall. They would only mow on sunny Saturday afternoons, apparently so that the most people could see their fancy (usually green) mower. I had one neighbor who I couldn't fault for his decision to get a rider. His mower purchase resulted in his wife doing all the mowing.

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Oh, that's what I need to do. Find someone to marry who had no idea why I don't like mowing and let her do it LOL.


That makes sense, I suppose. If I had welding equipment, I'd make my own mower deck and strap something on it. But I think you're right about mods like I'm talking about. Though, this is like a $350 mower, new, so I doubt there's much, if any resale value.

GearHead36 said:

Somehow I missed this. Cheapo lawn tractors tend to mow better than cheapo push mowers. I used to have a riding mower with a 36" or 38" deck (it's been a long time) and 12HP engine. It mowed better than my Toro Recycler. It was almost useless on the hills in my yard, so I got rid of it, but it impressed me that it mowed as well as it did with only 12HP. That could be due to most push mowers having the engine speed set too low.

Getting a lawn tractor, IMO, is a much better idea than an engine swap on a push mower.

BTW, almost all mower engines are vertical shaft.

Click to expand...

Even the riding mowers? I know the push ones are (HF has one vertical shaft and like 20 horizontal ones, which is why I'm interested in a rider (since no one would care if I mod a $200 broken rider and effectively make it a sleeper LOL)

Little Fish said:

Even the riding mowers? I know the push ones are (HF has one vertical shaft and like 20 horizontal ones, which is why I'm interested in a rider (since no one would care if I mod a $200 broken rider and effectively make it a sleeper LOL)

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Even riding mowers. I don't know of a single mower with a vertical shaft engine. I'm sure they're out there, but I'm not aware of them. Every gas powered riding mower at every big box store will have a vertical shaft engine. Now watch someone prove me wrong.

Power levels are stated gross torque at 2600 RPM per SAE J1940 and power levels are stated gross horsepower at 3600 RPM per SAE J1940.

Now this said ft/lb torque starts to drop off after reaching the peak at 2600 rpm and horse power continue to increase on most charts I have seen on small engines. IE your will have less torque at the gross. So when using an engine it will be loaded below the peak hp and will develop more torque. Also gross hp is before any load or optional equipment is added. So it is better to go by the ft/lb torque ratings; unless there is a Net hp rating. This way you are comparing apples to apples.

Now this said manufactures can adjust where the max torque develop by changing engine timing and fuel/air mixtures.

StarTech said:

Power levels are stated gross torque at 2600 RPM per SAE J1940 and power levels are stated gross horsepower at 3600 RPM per SAE J1940.

Now this said ft/lb torque starts to drop off after reaching the peak at 2600 rpm and horse power continue to increase on most charts I have seen on small engines. IE your will have less torque at the gross. So when using an engine it will be loaded below the peak hp and will develop more torque. Also gross hp is before any load or optional equipment is added. So it is better to go by the ft/lb torque ratings; unless there is a Net hp rating. This way you are comparing apples to apples.

Now this said manufactures can adjust where the max torque develop by changing engine timing and fuel/air mixtures.

Click to expand...

That all makes sense. Thanks!

Little Fish said:

About 60x80 and the front 50x30. Only reasons I can think they would take longer than a walk behind is they are underpowered, slow, or the yards have a lot of obstacles.

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Yeah I don't know for sure what exactly takes them so long to mow their lawns alI know is that it takes them forever but I don;t examine them closely when they do it. I'm pretty sure the one guy with the fairly new craftsman riding mower has it because of a psychological testosterone issue. The other 2, I think it's pure laziness. All 3 of them are young, like 40 or under. When they are done their lawns looks like ass, and not a hot chic's a$$, more like a Walmartian's a$$.

I can actually justify a riding mower for myself in terms of my home's property size as well as the amount of other properties I mow, but I don't have a way to transport it nor can I afford said transportation. I also don't have any storage space for it and I always figured a riding mower would cost more to maintain yearly than a push mower. I think about it every couple years, but quickly wake up to reality and just keep push mowing. It's exercise anyhow. I also have a lot of steep-ish banks to mow so I'd still do a lot of push mowing even if I had a rider. I'd say 35% of my mowing is too steep for a rider. But that means it also sucks to push mow lol.

Chuckers said:

Yeah I don't know for sure what exactly takes them so long to mow their lawns alI know is that it takes them forever but I don;t examine them closely when they do it. I'm pretty sure the one guy with the fairly new craftsman riding mower has it because of a psychological testosterone issue. The other 2, I think it's pure laziness. All 3 of them are young, like 40 or under. When they are done their lawns looks like ass, and not a hot chic's a$$, more like a Walmartian's a$$.

I can actually justify a riding mower for myself in terms of my home's property size as well as the amount of other properties I mow, but I don't have a way to transport it nor can I afford said transportation. I also don't have any storage space for it and I always figured a riding mower would cost more to maintain yearly than a push mower. I think about it every couple years, but quickly wake up to reality and just keep push mowing. It's exercise anyhow. I also have a lot of steep-ish banks to mow so I'd still do a lot of push mowing even if I had a rider. I'd say 35% of my mowing is too steep for a rider. But that means it also sucks to push mow lol.

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Sounds like you need a tractor and slope mower LOL. (One of the ones the highway teams mow weeds with)

When I have the grass get ahead of
Me I use my tractor and the flail mower or prior to that the brush hog. No grass or weed is too much. It happens if it
Rains a lot and I am traveling so when I get back it is tall and thick. Get a company or a farmer to cut it once
For you.

My take on mowing wet grass..Dont.
Takes so much power and it always looks like $hit .
Everyone thinks they "have to" mow that wet stuff. You'd be better off waiting a day or two ,letting it dry off and even if it grows more and get better results.. Its easier to mow 6" dry grass than it is to mow 4" wet grass.
JMO..

Chuckers said:

Yeah I don't know for sure what exactly takes them so long to mow their lawns alI know is that it takes them forever but I don;t examine them closely when they do it. I'm pretty sure the one guy with the fairly new craftsman riding mower has it because of a psychological testosterone issue. The other 2, I think it's pure laziness. All 3 of them are young, like 40 or under. When they are done their lawns looks like ass, and not a hot chic's a$$, more like a Walmartian's a$$.

I can actually justify a riding mower for myself in terms of my home's property size as well as the amount of other properties I mow, but I don't have a way to transport it nor can I afford said transportation. I also don't have any storage space for it and I always figured a riding mower would cost more to maintain yearly than a push mower. I think about it every couple years, but quickly wake up to reality and just keep push mowing. It's exercise anyhow. I also have a lot of steep-ish banks to mow so I'd still do a lot of push mowing even if I had a rider. I'd say 35% of my mowing is too steep for a rider. But that means it also sucks to push mow lol.

Click to expand...

Hey! Be kind
to us guys with psychological testosterone issues!

Bigger is always better. HP means nothing. you want as much torque as you can get. Torque is what does the work. think of it like a race car an engine builder will maybe tell you what the HP is but well never tell you what the Torque is and where it comes in and hits it's peak. the twisting is what gets you down the road or in this case is what spins the blade. about 25-20 years ago there was a "war" in the lawn mower world that manufactures were inflating the HP on the engines more the what it was so someone stepped in and say hey stop doing that and now they list the CC and the "Peak" torque. so in a nut shell get the biggest you can get and Oh I personally would never buy any CRAPSman power equipment. if your looking to replace an engine on a machine look at the Predator engine from Harbor freight they are cheap and really pretty powerful. you tube search project farm this dude tests everything I think you will probably find an engine test in his vast vault of video's and he explains why he tests and what he's testing and it's affect. super smart dude!

Here is an example how torque drops off as the RPM rised to the rated HP (3600 rpm). And every engine spec is different as they can adjust where peak torque occurs.

Briggs 10T502-1022-B1 158CC

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

First thing, make sure your blades are sharp. Not like a knife edge, but close. And you want the tip as close to a 90 degree edge as you can get it. Not rounded or curved, that will just push the grass aside. The tip cuts 99% of the grass. Considering how fast the blade spins, the mower moves hundredths of an inch from the time one tip is in front of the mower thill the opposing tip is in front. Then balance the blade. This is just as important as sharpening the blade. An out of balance blade will not spin as fast, and will bog down much easier.

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

It is unlikely that you would notice the difference of 10-20 cc. That is the Piston Displacement like Cu In. on vehicle motors was quoted in. In Racing terms, HP is how fast you hit the wall! Torque is how far you move the wall! You are asking too much of any small push mower. Raise it as high as possible and only mow 1/2 width til you get it under control. Now is a good time to spend the money on the best mower with biggest engine you can find before we are limited to Battery power by the Woke/treehugger/climate fools. Many change back to gas powered units after failing expectations with battery powered units, though they continue to improve.

What Little Fish said.

Torque and hp typically go hand in hand but you’re definitely looking for more torque. Hp=faster blade but not necessarily more power Torque=more powerful blade. Or Hp is how fast you hit the wall, Torque us how far you push the wall. Look for an engine with the most torque that will physically fit and work. It’ll help with what you’re looking to do. Now whether you’re deck will handle it in the long term is hard to say. Keep mounting bolts tightand watch for tearing and warping on the deck. Most likely you’ll be fine with the small amounts we’re talking. Shoot for something in the 8ftlb range and it’ll help for sure.

I pulled this from online because it uses less words than I would. Maybe it will clarify things. "When it comes to measuring power output for a lawnmower engine, torque is often a more accurate measurement than horsepower. Let me explain why:

1. Torque vs. Horsepower:
   • Horsepower (HP): Traditionally, lawn mower power was measured in horsepower. One horsepower is equal to 33,000 foot-pounds per minute. However, horsepower only calculates the overall work the engine can produce.
   • Torque: Torque, on the other hand, measures the rotational force produced by the engine. Specifically, it quantifies the power involved in turning the mower’s rotary blades. When you mow the lawn, the blades rotate and twist to cut the grass. The amount of power used for this action is known as torque1.
2. Why Torque Matters for Lawn Mowers:
   • Rotary Blades: When the mower’s blades are turned on, you’re witnessing an example of torque. Torque is essential for spinning the blades and allowing them to cut through grass.
   • Bogging Down: Lawn mowers with higher torque are less likely to get bogged down when cutting thick or long grass. More torque means more force delivered to the blade, making it easier to handle challenging conditions.
   • Gross Torque: Walk-behind lawn mowers typically have a power rating expressed in gross torque, not gross horsepower. This emphasizes the engine’s capability to turn the blade effectively1.
3. Choosing the Right Torque:
   • Consider your specific needs:
     • Yard Size: If you have a small, flat yard that you mow regularly, a mower with 4.50 to 5.50 ft-lbs of torque should suffice.
     • Grass Thickness: For larger yards with tall or thick grass, opt for a mower with more torque.
   • Longevity: The torque you choose directly affects the mower’s ability to complete the job and improve the motor’s lifespan. While torque alone isn’t the sole consideration, it’s essential when selecting a lawn mower. In summary, while horsepower remains crucial for riding lawn mowers, push lawn mower owners often prioritize torque. So, when evaluating lawnmower power, keep torque in mind—it’s the force that keeps those blades spinning

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

You dont want a mower for that. Something like a DR push string trimmer.

I have a question,my mower is a 22 craftsman B&S engine rated to run at 3500 RPMs but l have my mine running at 3370 would this hurt my mower

Little Fish said:

That's what I am planning to do. I'm letting the grass lift up a bit because it was pretty wet the other day when I mowed (no choice on that).

Does HP do anything? StarTech said it was torque. Is HP a better way to measure power output than torque?

Click to expand...

HP is rpm X torque.HP is more important than torque itself,because torque is only one part of the equation.I have seen a 1/16 hp electric motor pull concrete anchors out of the floor,but it was geared like a clock motor...very slow.
Most (but not all) small mowers are rated at 3600 rpm,so hp should be a fair comparison of the motors.Check the specs,including the torque and RPM at rated HP.
You can convert torque to horsepower by multiplying the torque rating by RPMs of the mower and dividing by 5,250. Now you can compare horsepower to horsepower.
A 21 inch mower should be almost unstoppable with a 5 hp motor,from my personal experience.

navydad2022 said:

I have a question,my mower is a 22 craftsman B&S engine rated to run at 3500 RPMs but l have my mine running at 3370 would this hurt my mower

Click to expand...

To get the max hp,it must be run at the specified speed.The fan for cooling is part of the equation,and most air cooled engines run cooler at rated speed than slower speed because of higher oil pressure,more air flow.
At the speed you are running,it should not have a big effect,unless you are "lugging" the motor under heavy load.
You are losing about 1 hp/
How are you checking the rpm?

navydad2022 said:

I have a question,my mower is a 22 craftsman B&S engine rated to run at 3500 RPMs but l have my mine running at 3370 would this hurt my mower

Click to expand...

By my calculations you have a blade tip speed of 19,400 fpm which is slightly above the maximum allowed under safety standards of 19,000 fpm

closecut said:

To get the max hp,it must be run at the specified speed.The fan for cooling is part of the equation,and most air cooled engines run cooler at rated speed than slower speed because of higher oil pressure,more air flow.
At the speed you are running,it should not have a big effect,unless you are "lugging" the motor under heavy load.
You are losing about 1 hp/
How are you checking the rpm?

Click to expand...

True but in the case of a rotary mower blade tip speed requirements will override max engine rpm, so even if the engine is rated at 3500 rpm blade tip requirements can drop that below max like with the example of the 22 inch mower then max engine rpm would be closer to 3300.

navydad2022 said:

I have a question,my mower is a 22 craftsman B&S engine rated to run at 3500 RPMs but l have my mine running at 3370 would this hurt my mower

Click to expand...

I'm not a mod - but hijacking a thread does 2 things...

1. It's unfair to the OP because it takes steam away from his thread.

2. It's unfair to yourself because you will get more eyes on your specific question (even if it is related to OP) and therefore get more answers.

Thus, please start your own thread if you have a question.

Find an old push mower that still runs. Set wheels for tallest cutting height. push down on the handle and get those front wheels way off the ground. Push it slowly into your over growth. Mow for a while and rake up the cuttings. Keep moving on area by area. Go back over it until you can mow with all 4 wheels on the ground.
Start mowing with your good mower.

4getgto said:

My take on mowing wet grass..Dont.
Takes so much power and it always looks like $hit .
Everyone thinks they "have to" mow that wet stuff. You'd be better off waiting a day or two ,letting it dry off and even if it grows more and get better results.. Its easier to mow 6" dry grass than it is to mow 4" wet grass.
JMO..

Click to expand...

My yard is a swamp. It hasn't rained for 3 days and there's still standing water...

tcpuccio1 said:

Bigger is always better. HP means nothing. you want as much torque as you can get. Torque is what does the work. think of it like a race car an engine builder will maybe tell you what the HP is but well never tell you what the Torque is and where it comes in and hits it's peak. the twisting is what gets you down the road or in this case is what spins the blade. about 25-20 years ago there was a "war" in the lawn mower world that manufactures were inflating the HP on the engines more the what it was so someone stepped in and say hey stop doing that and now they list the CC and the "Peak" torque. so in a nut shell get the biggest you can get and Oh I personally would never buy any CRAPSman power equipment. if your looking to replace an engine on a machine look at the Predator engine from Harbor freight they are cheap and really pretty powerful. you tube search project farm this dude tests everything I think you will probably find an engine test in his vast vault of video's and he explains why he tests and what he's testing and it's affect. super smart dude!

Click to expand...

I love PF!

Thanks for the advice. That's exactly what I needed.

I think you have had enough answers regarding cutting your grass, you let it get to long, etc so I’m not going there. Also as stated you could install a much larger engine to do the job but your deck won’t handle it. I think all this is covered. But you asked about more CC’s. CC’s is metric and stands for cubic centimeters kind of like CI (cubic inches) in US terms. The more CC’s your engine is the larger the displacement kind of like a Chevy 327 compared to a 427. So in theory everything being equal a 170 CC engine should have more power than a 140 as would 220 CC have more power than a 170. The issue becomes mounting the engine to your deck and the length of the shaft protruding through your deck and will your blade and hardware mount to the larger engine. By the time you are done you may be money ahead to find a good used mower to your liking. It is doable provided your hardware and the engine are a match up. I don’t think it will solve your issue with your existing mower and conditions. The deck design of any mower has a lot to do with how the grass is discharging out the shoot. I do think that if you are planning to swap your 140CC engine for a 170CC engine you will notice lift or no difference and I feel personally you would be wasting your time and money.
I wish you the best and good luck on your decision.

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

Depending on the blade diameter, the most common engine CC ratings are 159 and 196 for walk behind mowers. These numbers divided by 15 gives you a rough idea of its horse power at maximum rpm. (Back in the old days, this was what was on the engines label telling you what it was rated at.) This answers your question in the simplest terms. If you care to read below, you’ll find the rest of the story below:

What you need to efficiently cut grass (work) is torque and this is dependent on engine rpm. The higher the rpm, the higher the torque the maximum level of which is also dependent on the number of CC’s. Lawnmower engines typically are regulated to run around 1500 rpm by the governor at no load (it’s not doing any work,). At this speed the engine is producing about 40% of its rated torque. When you start to cut grass (load), the engine begins to slow down. The governor senses this and opens the throttle causing the engine rpm and the torque to increase the necessary amount to cut the grass. (You will notice an increase in engine noise.) It will open the throttle until the engine is producing it’s maximum rated torque. Any significant increase in the load after this will cause the engine to stall.

Indecently. A 21” mower with a 140CC, Though that’s a little light, should be able to cut grass 4 to 5” tall. If your mower has a lot of miles on it, I’d take the cover off and make sure the governor linkage is free to move.

I welcome that If anyone notices any significant mistakes in the above to correct me.

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

Click to expand...

Power just may not be the best answer. Deck design and blade efficiency may make a big difference. We also don't know if the present engine is working at its optimum.

Little Fish said:

My yard is a swamp. It hasn't rained for 3 days and there's still standing water...

Click to expand...

Sounds like you need to take the money you want to spend on an engine/mower and put it toward fixing that drainage issue instead.

Put a B&S 850 engine on it

aussielawny said:

Put a B&S 850 engine on it

Click to expand...

Yea that's the ticket...

Chuckers said:

Sounds like you need to take the money you want to spend on an engine/mower and put it toward fixing that drainage issue instead.

Click to expand...

Chuckers has the best post in all 6 pages.
Forget about engine HP and Torque. I don't recall if you have a push or self-propelled mower. My discussion is for a push mower. You need to raise the deck to cut tall grass. The top of the deck should be equal to or lower than the grass height. I can think of two options. 1. You could try figuring out a way to install larger wheels. You might need longer axles to do this because the cutting area of the deck is wider than the wheels area. 2. Here is an idea way outside the box which is serious even though it sounds ridiculous. Figure out how to add outdoor plate style casters to bolt-on wood or metal crosspieces for high grass. Just remove the cross piece assemblies for regular mowing.
Next best choice is a wheeled string trimmer with a high-lift kit. Again, serious although it sounds ludicrous.
One of my friends has a problem with standing water after winter snows melt or after periods of lots of rain. He is waiting for me to design/build a pontoon or hovercraft tractor.

The guy is trying to mow a lawn that's like a swamp and standing water. Ain't a mower out there to this regardless of torque and horsepower. Either let it turn into a marsh and enjoy the frogs or wait till it dries out..

Davenj4f said:

First thing, make sure your blades are sharp. Not like a knife edge, but close. And you want the tip as close to a 90 degree edge as you can get it. Not rounded or curved, that will just push the grass aside. The tip cuts 99% of the grass. Considering how fast the blade spins, the mower moves hundredths of an inch from the time one tip is in front of the mower thill the opposing tip is in front. Then balance the blade. This is just as important as sharpening the blade. An out of balance blade will not spin as fast, and will bog down much easier.

Click to expand...

I did that. You're right that the tip cuts most of the grass initially, but then the other parts come into play for mulching and throwing it into the bag.
Even after sharpening, it was not very good. Definitely improved, but not great.

sbspence said:

Torque and hp typically go hand in hand but you’re definitely looking for more torque. Hp=faster blade but not necessarily more power Torque=more powerful blade. Or Hp is how fast you hit the wall, Torque us how far you push the wall. Look for an engine with the most torque that will physically fit and work. It’ll help with what you’re looking to do. Now whether you’re deck will handle it in the long term is hard to say. Keep mounting bolts tightand watch for tearing and warping on the deck. Most likely you’ll be fine with the small amounts we’re talking. Shoot for something in the 8ftlb range and it’ll help for sure.

Click to expand...

Thanks! Any recommendations on where to find one? And are all vertical shaft engine shafts the same (so I could just swap the B&S to whatever I find without adapters)?

I'm late to this discussion but wanted to add my 2-cents about replacement engines. About 30 years ago I had a small engine repair shop. I found that the vertical shaft B&S engines that Craftsman placed on their push mower decks were unique due to PTO shaft length and blade mounting. They forced most customers to have to get their replacement engine from Sears/Craftsman. Briggs & Stratton would not sell the engine to even repair shops. So if you are planning to replace your engine on a Craftsman deck be mindfully of that.

Chiefwebb said:

I'm late to this discussion but wanted to add my 2-cents about replacement engines. About 30 years ago I had a small engine repair shop. I found that the vertical shaft B&S engines that Craftsman placed on their push mower decks were unique due to PTO shaft length and blade mounting. They forced most customers to have to get their replacement engine from Sears/Craftsman. Briggs & Stratton would not sell the engine to even repair shops. So if you are planning to replace your engine on a Craftsman deck be mindfully of that.

Click to expand...

This is a new craftsman. I think it may have changed since B&D bought them out. But it may he the same, who knows.

Little Fish said:

Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL

Click to expand...

That first answer did answer your question but your questions were not the only ones that needed answered.

Cutting tall grass is not just about engine power.
It's mostly about discharging the grass out the side with a side discharge option that many have AND using the discharge deflector attachment.

Mulching and tall grass do not go together

You would be amazed how different the same mower is with flap down and mulching vs lifting it and putting the chute in (always with engine off of course).

It's like a completely different mower.

Also set your engine rpms to about 3000-3100 as some will be down around 2800.

Also you need to cut tall overgrown grass on highest height setting out maybe 1 notch down.
This helps a lot too.

I don't EVER cut grass that just needs to be cut. Everytime I cut it is quite overgrown.

jimbir said:

Depending on the blade diameter, the most common engine CC ratings are 159 and 196 for walk behind mowers. These numbers divided by 15 gives you a rough idea of its horse power at maximum rpm. (Back in the old days, this was what was on the engines label telling you what it was rated at.) This answers your question in the simplest terms. If you care to read below, you’ll find the rest of the story below:

What you need to efficiently cut grass (work) is torque and this is dependent on engine rpm. The higher the rpm, the higher the torque the maximum level of which is also dependent on the number of CC’s. Lawnmower engines typically are regulated to run around 1500 rpm by the governor at no load (it’s not doing any work,). At this speed the engine is producing about 40% of its rated torque. When you start to cut grass (load), the engine begins to slow down. The governor senses this and opens the throttle causing the engine rpm and the torque to increase the necessary amount to cut the grass. (You will notice an increase in engine noise.) It will open the throttle until the engine is producing it’s maximum rated torque. Any significant increase in the load after this will cause the engine to stall.

Indecently. A 21” mower with a 140CC, Though that’s a little light, should be able to cut grass 4 to 5” tall. If your mower has a lot of miles on it, I’d take the cover off and make sure the governor linkage is free to move.

I welcome that If anyone notices any significant mistakes in the above to correct me.

Click to expand...

I was going to ask where you came up with these numbers....
Not accurate at all.

Dividing CC's by 15 isn't even close to hp (unless you have a supercharger to put on it too).
It's more like divide by 25- almost 30. But there really isn't a common rule of thumb like that.

RPMs - mowers are typically fairly close to 3000 RPMs.
Doesn't matter if it's no load or not as the governor does do what you explained to maintain the same speed under load but only up to the engines torque ability. The most it can do is open throttle 100% and it often does that in taller grass.

Many mowers are set to 2900 +or- 100 rpm. Some are at 3100 etc.
They used to rate the engines at 3600 for hp ratings but that changed 25+ years ago.
Blades also got longer with old mowers being 18,19,20 inches until 21 became most common and then lots of 22s.

This forced them to lower RPMs to keep blade tip speeds under the legal limit.

TobyU said:

That first answer did answer your question but your questions were not the only ones that needed answered.

Cutting tall grass is not just about engine power.
It's mostly about discharging the grass out the side with a side discharge option that many have AND using the discharge deflector attachment.

Mulching and tall grass do not go together

You would be amazed how different the same mower is with flap down and mulching vs lifting it and putting the chute in (always with engine off of course).

It's like a completely different mower.

Also set your engine rpms to about 3000-3100 as some will be down around 2800.

Also you need to cut tall overgrown grass on highest height setting out maybe 1 notch down.
This helps a lot too.

I don't EVER cut grass that just needs to be cut. Everytime I cut it is quite overgrown.

Click to expand...

I tried that. I only have the bag for the mower (just found it as I was cleaning out the garage the other day)

TobyU said:

That first answer did answer your question but your questions were not the only ones that needed answered.

Cutting tall grass is not just about engine power.
It's mostly about discharging the grass out the side with a side discharge option that many have AND using the discharge deflector attachment.

Mulching and tall grass do not go together

You would be amazed how different the same mower is with flap down and mulching vs lifting it and putting the chute in (always with engine off of course).

It's like a completely different mower.

Also set your engine rpms to about 3000-3100 as some will be down around 2800.

Also you need to cut tall overgrown grass on highest height setting out maybe 1 notch down.
This helps a lot too.

I don't EVER cut grass that just needs to be cut. Everytime I cut it is quite overgrown.

Click to expand...

I tried to open the side discharge. I don't have a chute, so it just clogged immediately (I had a stick to hold it open). Same with the rear discharge, except it only clogged if I didn't set it to fully open. It worked better, but it still bogged down bad.

For all the people saying to set it to the highest setting: Duh. That was the first thing I did. 4" isn't really gonna make a difference to 18-24" grass cutting LOL. Even Hondas only go to 5 or 6"...

Little Fish said:

Did you read the first reply to this thread? It answered my question. Only issue after that was what would be enough power to get through the grass. Which I would still ask a pro, since they have more experience than I do (I was actually a pro, but I only ran a Honda and did small jobs, so I never experienced other movers and how they work).

And where else would I ask about this? Car guys won't know, and engineers are too busy making money and working to death to reply to some random guy on a forum LOL

Click to expand...

If your question was answered already, just say "Thank you" and don't respond any more.

Little Fish said:

I tried that. I only have the bag for the mower (just found it as I was cleaning out the garage the other day)

I tried to open the side discharge. I don't have a chute, so it just clogged immediately (I had a stick to hold it open). Same with the rear discharge, except it only clogged if I didn't set it to fully open. It worked better, but it still bogged down bad.

For all the people saying to set it to the highest setting: Duh. That was the first thing I did. 4" isn't really gonna make a difference to 18-24" grass cutting LOL. Even Hondas only go to 5 or 6"...

Click to expand...

Hire a heavy-hitter mower for the first cut, then keep it mowed short.

Push are never meant to be used as a bush hog. HD walk behind string trimmers works better but even they have their limits. Even when I was teenager I when I had to cut high grass it took a lot forward and backward movement of the mowers. And like Sunday here I was using a Gravely HD52 ZTR that keep clogging up the deck in high thick grass. Whenever the deck stopped discharging I would have back up raise the deck and then disengage to PTO so the grass clippings would fall down where they suspended over the blades. Then re-engage the PTO and lower the deck and cut until it stopped discharging again. Every so often I had repeat this cycle but I finally got the tall thick grass mowed.

Little Fish said:

I tried that. I only have the bag for the mower (just found it as I was cleaning out the garage the other day)

I tried to open the side discharge. I don't have a chute, so it just clogged immediately (I had a stick to hold it open). Same with the rear discharge, except it only clogged if I didn't set it to fully open. It worked better, but it still bogged down bad.

For all the people saying to set it to the highest setting: Duh. That was the first thing I did. 4" isn't really gonna make a difference to 18-24" grass cutting LOL. Even Hondas only go to 5 or 6"...

Click to expand...

So you have a cheap residential push mower that can't be set up for side discharge because you lost the chute, you want to mow 18"-24" WET grass, your mower won't do it... and you think that a larger engine is the answer?

BTW, mowing high WILL make a difference. The lower you go, the thicker the grass gets.

TobyU said:

I was going to ask where you came up with these numbers....
Not accurate at all.

Dividing CC's by 15 isn't even close to hp (unless you have a supercharger to put on it too).
It's more like divide by 25- almost 30. But there really isn't a common rule of thumb like that.

RPMs - mowers are typically fairly close to 3000 RPMs.
Doesn't matter if it's no load or not as the governor does do what you explained to maintain the same speed under load but only up to the engines torque ability. The most it can do is open throttle 100% and it often does that in taller grass.

Many mowers are set to 2900 +or- 100 rpm. Some are at 3100 etc.
They used to rate the engines at 3600 for hp ratings but that changed 25+ years ago.
Blades also got longer with old mowers being 18,19,20 inches until 21 became most common and then lots of 22s.

This forced them to lower RPMs to keep blade tip speeds under the legal limit.

Click to expand...

Thanks for the question. I got my numbers from an online calculator. I'll admit I was a very skeptical. I did more research and found a number of sites that showed the divisor could be anywhere between 25 and 40. This makes a lot more sense to me. In the future, I'm going to stick with 40 and even that seems a little low

Little Fish, Too many pages for me to read again, too few remaining brain cells to remember.
Did you get the mess cut down? Are the waterlogged lawn and tall grass issues annual? How deep into the year do they remain? Do they reoccur during the summer with heavy rain? Do neighbors have the same issues? Please add some pictures of your bog (not trying to be nasty).
People have posted some good ideas. I hope by now that you have given up on the Tim Allen engine replacement approach. Please answer my questions and hopefully followers will reset their thinking.

Little Fish said:

I tried that. I only have the bag for the mower (just found it as I was cleaning out the garage the other day)

I tried to open the side discharge. I don't have a chute, so it just clogged immediately (I had a stick to hold it open). Same with the rear discharge, except it only clogged if I didn't set it to fully open. It worked better, but it still bogged down bad.

For all the people saying to set it to the highest setting: Duh. That was the first thing I did. 4" isn't really gonna make a difference to 18-24" grass cutting LOL. Even Hondas only go to 5 or 6"...

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You should never really open one with the back open and even if you prop it up in just a little bit it still gets grass out of your feet and stuff is annoying. The stick method for the side works but typically not as well as the actual discharge flat. It should be able to order one online. They work quite nicely.

jimbir said:

Thanks for the question. I got my numbers from an online calculator. I'll admit I was a very skeptical. I did more research and found a number of sites that showed the divisor could be anywhere between 25 and 40. This makes a lot more sense to me. In the future, I'm going to stick with 40 and even that seems a little low

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Classic example of why you shouldn't believe everything you find from google, we Wikipedia or online. Lol

I have literally worked on thousands of these mowers and I know plenty of people today are skeptical and don't like to believe anything a person says but I only speak in actual facts from experience.
If I don't know, I clearly tell somebody I really don't know but this is what I would try etc.

Little Fish said:

I want to get a mower engine and swap onto my little 21" 140cc Craftsman. I let my yard get way too high and went to mow it, but it was barely able to handle it, and I had to push it 2ft, backtrack 3, then go forward slowly.

Anyway, I was looking at a new mower, but they're all 150 or 170 or 163 cc (for the well rated ones. There's several 200ish cc ones for outrageous money, or with like 2 stars.

So, I'm curious. How much does engine CC actually do? Will I notice a difference between my 140cc and a 150? What about 163 or 170? Where would I need to go to buy a bigger engine that I could just swap onto the mower?

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CC refers to engine size, not horsepower. Before B&S went and started measuring horsepower differently, all U.S. made equipment was measured in cu inches. If you are mulching/bagging too tall grass, NO LAWN MOWER [save a 2 cycle Lawnboy] will cut that mess. Just get cut short, and use your old machine. CC=cubic centimeter, and cu inch= cubic inches.

Chiefwebb said:

I'm late to this discussion but wanted to add my 2-cents about replacement engines. About 30 years ago I had a small engine repair shop. I found that the vertical shaft B&S engines that Craftsman placed on their push mower decks were unique due to PTO shaft length and blade mounting. They forced most customers to have to get their replacement engine from Sears/Craftsman. Briggs & Stratton would not sell the engine to even repair shops. So if you are planning to replace your engine on a Craftsman deck be mindfully of that.

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The B&S parts store shows several engines for sale and in stock- the 17.5HP was about $750, IIRC.

georgPru2 said:

CC refers to engine size, not horsepower. Before B&S went and started measuring horsepower differently, all U.S. made equipment was measured in cu inches. If you are mulching/bagging too tall grass, NO LAWN MOWER [save a 2 cycle Lawnboy] will cut that mess. Just get cut short, and use your old machine. CC=cubic centimeter, and cu inch= cubic inches.

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How do they measure HP now and why does the change from cu inches to Metric matter? HP is a calculated value, just like Newton-Meters or Joules.

T

Gym123 said:

How do they measure HP now and why does the change from cu inches to Metric matter? HP is a calculated value, just like Newton-Meters or Joules.

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The Change to metric from Normal is thanks to the LIEberals in Canada. Rated HP became a huge problem when JD was caught exaggerating the true HP. They paid Dearly for this. Now Small engines are measured in Torque Ft or in. pounds which few understand.
HP is how fast you hit the wall, Torque is how far you move the wall! You're welcome.

sounds like you need a goat instead of a mower...

Gord Baker said:

Rated HP became a huge problem when JD was caught exaggerating the true HP. They paid Dearly for this.

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This happened to Briggs too. Long ago..

Gord Baker said:

T

The Change to metric from Normal is thanks to the LIEberals in Canada. Rated HP became a huge problem when JD was caught exaggerating the true HP. They paid Dearly for this. Now Small engines are measured in Torque Ft or in. pounds which few understand.
HP is how fast you hit the wall, Torque is how far you move the wall! You're welcome.

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The manufacturers could have been made to show HP and Torque in the way many other engines are rated, but it would confuse the people who don't care about or understand car performance- show a Power and Torque curve and where it was connected to the measurement device- crank or at some point after, like the PTO shaft. Done. No need to change to Metric by Canada, but this kind of shows that their legislators don't quite understand how this could have been solved.

If a manufacturer wants to lie, let them suffer the consequences from being discovered.

I worked for boat dealers and some engine manufacturers showed the power and torque measured at the crank while others showed it at the prop. We had discussions (our side) and arguments (the other side) at boat shows where they went on about the power of their boats being measured at the prop, while ours were measured at the crank- at one point, I said "But torque is what turns the prop shaft" and they left us alone.

I heard a definition of Torque when I was in college at an engineering school that involved pushing something down while standing at a toilet first thing in the morning, resulting in the person being flipped over.......it wasn't the flush handle on the toilet.

To the OP-

The saying in drag racing "There's no replacement for displacement' is still valid for these, but we're working with much smaller engines and in order to really see the effect of a larger engine for this purpose, we need to look at the whole machine. As an example, the 17.5HP Briggs engine is .5 Liter. That's not much but there are ways to produce more torque- longer stroke, created by the crankshaft and using a smaller diameter piston for the same displacement. The crank is rotated by combustion in a larger circle, so we need to look at it as if someone had put a pipe on a wrench in order to increase torque- it's harder to rotate the crank with a shorter lever arm (smaller diameter of rotation).

Then, we need to look at the effect of the grass resisting the blade's rotation and this is why a sharp blade and correct mower speed are important- the blade is only sharpened close to the end and moving too fast causes the grass to pass the sharp edge, which just grabs and causes the engine to bog.

If you slow down, it will cut better. Extremely tall grass will require more than one pass with the deck set higher for the first.

I put a predator V twin on my push mower, it sounds like that is what the OP needs

Sorry if this has been mentioned, earlier (several pages would not open for me).

Torque is a measure of the ability to do work - GYM 123 put it very well.

Combustion chamber capacity (cc or cu") is but one component of the engines' ability to deliver torque. Most of the old B&S yellow industrial engines, deliver way more torque for the same capacity (often lower hp) as a modern B&S because of longer conrods/larger flywheel/ possibly higher compression.

The comment "There's no replacement for displacement' is still valid ..." no longer holds good, with the possible exception of drag racing. A small high revving engine, (often high compression) transmitting power through gear box can & does deliver more torque, usually for lower fuel consumption.

The great unwashed (general public) just want something, that makes a noise, boast about the hp. That's why small motors almost always have HP boldly displayed on the side.

140 CC's size engine is approximately 9 HP at 3600 RPM. Most mowers are rated at a top speed of 3600 RPM.

Sounds like you are trying to mow thick tall grass, this engine will not handle that for very long.

Even a 20 HP engine would have a bit of a struggle.

I suggest a bigger mower. Putting a bigger engine on that small chassis will be too much work for no gain, and they don't make blade adapters for bigger engines like that. The push mower decks are light pressed steel in most cases, and a larger engine would destroy the mounting areas in a short time.

Spend the money and look at the commercial grade 36" self-propelled walk behind mowers.

Auto Doc's said:

140 CC's size engine is approximately 9 HP at 3600 RPM. Most mowers are rated at a top speed of 3600 RPM.

Sounds like you are trying to mow thick tall grass, this engine will not handle that for very long.

Even a 20 HP engine would have a bit of a struggle.

I suggest a bigger mower. Putting a bigger engine on that small chassis will be too much work for no gain, and they don't make blade adapters for bigger engines like that. The push mower decks are light pressed steel in most cases, and a larger engine would destroy the mounting areas in a short time.

Spend the money and look at the commercial grade 36" self-propelled walk behind mowers.

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140 CC engine is about 3.5 to 4 horsepower.

Skippydiesel said:

Sorry if this has been mentioned, earlier (several pages would not open for me).

Torque is a measure of the ability to do work - GYM 123 put it very well.

Combustion chamber capacity (cc or cu") is but one component of the engines' ability to deliver torque. Most of the old B&S yellow industrial engines, deliver way more torque for the same capacity (often lower hp) as a modern B&S because of longer conrods/larger flywheel/ possibly higher compression.

The comment "There's no replacement for displacement' is still valid ..." no longer holds good, with the possible exception of drag racing. A small high revving engine, (often high compression) transmitting power through gear box can & does deliver more torque, usually for lower fuel consumption.

The great unwashed (general public) just want something, that makes a noise, boast about the hp. That's why small motors almost always have HP boldly displayed on the side.

Click to expand...

I haven't seen small engines that were anything but normally aspirated, so displacement still matters. These don't have super/turbochargers or gearboxes that multiply torque in the way cars & trucks do, so crankshaft offset and piston diameter are about the best ways to increase torque.

However, the 'powers that be' in some places want small engines to go away and they're not at the same level of technical development as cars, trucks and other vehicles, so we're stuck slogging through tall grass with 'less than commercial' mowers.

Auto Doc's said:

140 CC's size engine is approximately 9 HP at 3600 RPM. Most mowers are rated at a top speed of 3600 RPM.

Sounds like you are trying to mow thick tall grass, this engine will not handle that for very long.

Even a 20 HP engine would have a bit of a struggle.

I suggest a bigger mower. Putting a bigger engine on that small chassis will be too much work for no gain, and they don't make blade adapters for bigger engines like that. The push mower decks are light pressed steel in most cases, and a larger engine would destroy the mounting areas in a short time.

Spend the money and look at the commercial grade 36" self-propelled walk behind mowers.

Click to expand...

These are a bit like crotch rocket engines- wind it out and the power is there (measurable) but there's not much torque behind them.

I bought a bagger attachment for the Ariens 42" and the seller had replaced their 46" with a light commercial model because the cost wasn't much higher, but the build quality and performance were better.

As I read about these, it seems that some of the manufacturers are using the Ron White reasoning for giving diamonds to women- "Diamonds, this'll shut her up". Here- give them this, it will work. For awhile.".

The working torque is something that is determine by the ignition timing as if too late at high rpms then the fuel just burns off producing less power even though there is a lot rpms. This the problem using fix timed ignition systems as there is optimum timing point for max torque. And small engines definitely have their limits.

Sometimes it is valve timing or opening up how the engine breathes. I have taken old L head 12.5hp engine and shifted the camshaft by one tooth and therefore shift the torque curve to the higher rpm end making the engine more powerful at the 3600 rpm end. This was on an old Murray rider that was a gutless wonder before the change.

Something we not able to do here is change the grind on camshafts and have variable duration lifters. I took a small 265 V8 and got it where I had plenty of torque and with nearly 23 MPG average with a highway MPG of 32 mpg. It came from the factory rated for 16 mpg highway. I even seen it to get 45 mpg tailgating a 18 wheeler on the interstate.
Now this something I don't recommend anyone doing unless you are in contact with the rig driver.