Export thread

Hello all! I am working on a mower for one of my neighbors, that can't get it started. I took it back to my garage and started looking it over. Something is a bit off of it. It's a 650 series briggs 190cc L head. The pull rope does not have as much length as I would expect, and there's a plastic piece missing where the pull rope handle meets the cooling shroud. I feel like it's possible someone else worked on it before, which would explain its strange behavior, which I'll get to in a minute.

Of course I suspected the carb. I fixed one just the other day for someone where as usual, it was just bad gas/plugged carb. I dropped the bowl and checked the jet, but they were pretty clean and there was no corrosion. So I put it back together and checked for spark. There was spark. I then took the air filter off and was greeted by the MOST dirt I have ever seen. It was packed so tight that the fins of the filter weren't visible, it was a smooth rectangle of dirt. I figured that was the problem, and tried starting it with no filter. It would start to kinda go, but it kicked back a bit and I swear I could see exhaust coming out of the intake. After pulling hard for a few minutes I got it to start, and it runs rough. It revs up and down rapidly like it's surging, but also sounds strange. I then assumed it was the flywheel key. I checked the blade, and it is ever so slightly off balance, but not badly. I checked under the starter cup, but the key is fine. So I tested a new spark plug, gapped properly. Still ran badly. I tested a different ignition module. Still ran badly.

I was pretty confused at this point. I took off the head to look at the valves and piston. The piston and cylinder look ok, and the valves seat firmly when they should. The compression release is working too.

With the kill wire removed, I put the engine brake on and it smoothed out a bit with a load, still not perfect.

Everything I know to check is exhausted at this point, spark, ignition, timing, valve seating, carburetor, etc. are ok. At this point, the only thing I can think of is MAYBE someone else rebuilt this engine at some point and put the camshaft in wrongly (lined up timing gears wrong). Before I take it all the way apart, however, I just wanted to get other opinions. Anyone have ideas?

Thanks!

Did you check the float level? I’m thinking being that dirty, the carb has been sitting around with old fuel and the seat has swelled, creating a lean running condition.

Still sounds like a lean condition. Try getting it running and put your finger over the carb intake enough to choke it some, see if it smooths out.

Figured it out. I'm an idiot. The key was sheared after all. It sheared at an angle so that it looked whole on the top, but wasn't really. In fact, it was almost 1/5 of a turn off. I can't believe it ran at all. I'll go replace it tomorrow. I decided to check one of my other engines that is running rough to see if I should order more than one key, and it looks like this:


Is that serious enough to be a problem or can I leave it. This one runs rough like I said, but I wouldn't think this is too too severe. Flywheel wasn't coming off when I hit it with the old hammer and chisel, so I stopped because I don't want to damage it. I broke the flywheel on one of my scrap engines hitting it hard, so I stopped prying until I get an opinion as to if there is even a reason to.

That one is starting to shear, I would replace it also.

Think about it this way. The key is offset which is advancing the timing about 6 degrees so instead of firing at 22 degrees BTDC it is now firing at 28 degrees BDTC.

Good to know, thanks. I'll try and get the flywheel off without using the chisel and hammer. Maybe I finally invest in a proper puller.

Put a pry bar under the fly wheel, screw the bolt back onto the crank until the crank is about 1/4in below the top of the nut. Then give it a whack or two. (the nut) It should pop off without having to hit it too hard. Easy peasy, japaneasy.

Just make sure you got the pry bar on something pretty solid. Taryl makes a pretty good video about this if you're unsure.

I just cringe at the thought doing this on today's thin crankcases and ultra light flywheels. I havedone split in two flywheels and hole in crankcases where a DIYer use the pry bar trick.

Just a note some the holes for pulling do need to be tapped for first time use.

P have

StarTech said:

I just cringe at the thought doing this on today's thin crankcases and ultra light flywheels. I havedone split in two flywheels and hole in crankcases where a DIYer use the pry bar trick.

Just a note some the holes for pulling do need to be tapped for first time use.

Click to expand...

TylerFrankel1 said:

Good to know, thanks. I'll try and get the flywheel off without using the chisel and hammer. Maybe I finally invest in a proper puller.

Click to expand...

The proper puller is cheap, a lot cheaper than a new engine. I have photo of using the pry and hit method resulting in hole in thin casting area under the flywheel as mentioned above by StarTech - not worth the chance and you can make your own puller for that matter.
Walt Conner

StarTech said:

I just cringe at the thought doing this on today's thin crankcases and ultra light flywheels. I havedone split in two flywheels and hole in crankcases where a DIYer use the pry bar trick.

Just a note some the holes for pulling do need to be tapped for first time use.

Click to expand...

It takes finesse. And a little luck.

I do use flywheel knockers without a pry bar and a 2 lb brass hammer. Matter of fact I had several made for smaller flywheels and I use a harmonic balancer puller most of the larger ones. I did make one puller recently to get HydroGear pulley off out bar stock.

So far I had only one flywheel I couldn't remove but some idiot torqued it down with an impact and fused it to the crankshaft.

I would never do this without making sure the bottom of the pry bar being on something solid. And the end of it on the inside edge of the fly wheel. Start with a couple of small taps. Then increase as needed. I'll never just hit one with a lot of force. LOL. The crank is connected to some important parts inside.

PTmowerMech said:

Put a pry bar under the fly wheel, screw the bolt back onto the crank until the crank is about 1/4in below the top of the nut. Then give it a whack or two. (the nut) It should pop off without having to hit it too hard. Easy peasy, japaneasy.

Just make sure you got the pry bar on something pretty solid. Taryl makes a pretty good video about this if you're unsure.

Click to expand...

Taryl Dactal is awesome. Unfortunately he's taking a break during all the Corona nonsense. Anyway, yeah, I think I'll get a puller for safety reasons. Like I said something cracked on my scrap engine just the other day so I'm nervous now. Really hope the holes are already tapped.

If you have a buddy with a good back, have him (her?) lift the mower by the flywheel, give the top of the crank/nut a good whack with the hammer. By holding it this way the shock to the flywheel is cushioned and the weight and shock will pop the flywheel loose. I like to screw the nut down flush with the top of the crank if possible.

TylerFrankel1 said:

Taryl Dactal is awesome. Unfortunately he's taking a break during all the Corona nonsense. Anyway, yeah, I think I'll get a puller for safety reasons. Like I said something cracked on my scrap engine just the other day so I'm nervous now. Really hope the holes are already tapped.

Click to expand...

You might give it a couple of taps with the hammer and pry bar method. Just to see. A lot of times, they don't need more than a couple of taps.

PTmowerMech said:

You might give it a couple of taps with the hammer and pry bar method. Just to see. A lot of times, they don't need more than a couple of taps.

Click to expand...

I did, nothing yet. I may also leave this one alone. I checked the blade again and apparently the boss was damaged and the blade wasn't flat. I straightened it out and it's much smoother now, though it runs a bit low on the RPMs. I think the timing is a smidge off.

I tried to create a puller this morning by drilling out the holes to 3/16, then tried to threat some long 1/4 bolts in. They weren't self tapping and sure enough it did not work. I think I'll go get a harbor freight puller set that will be good for all my jobs from now on.

TylerFrankel1 said:

I did, nothing yet. I may also leave this one alone. I checked the blade again and apparently the boss was damaged and the blade wasn't flat. I straightened it out and it's much smoother now, though it runs a bit low on the RPMs. I think the timing is a smidge off.

I tried to create a puller this morning by drilling out the holes to 3/16, then tried to threat some long 1/4 bolts in. They weren't self tapping and sure enough it did not work. I think I'll go get a harbor freight puller set that will be good for all my jobs from now on.

Click to expand...

Then you have to show it who's boss, BY GOD!!!!!! Give it a good whack. LOLOLOLOL

You're going to need to tap the holes anyway and don't buy HF tap and die set. They are lousy to say the least.

Self tapping screws can be made if you know how.

StarTech said:

You're going to need to tap the holes anyway and don't buy HF tap and die set. They are lousy to say the least.

Self tapping screws can be made if you know how.

Click to expand...

Good news. The mower I started this thread on, that had the fully sheared key, is now fixed and back with its owner. +40 bucks for me. It needed nothing but the flywheel key. I also sharpened the blade best I could and balanced it. (He needs to replace it after hitting all the stuff he has because it's dinged pretty bad, but he doesn't really care so I don't either). I changed the oil and put in fresh fuel. I put in the cleaned out air filter, it seemed good enough to use again after a good clean, and it starts on one pull. Runs great.

The other mower I had mentioned before that I said was also running rough has been my focus now. It is not going as well. (It's the one I posted a picture of with a semi-sheared key).

When I tried to be crafty and make my own puller, I ended up breaking a bolt head off, and a bolt got stuck in the flywheel. I just snapped it off at its base and thought nothing of it, until I tried to use my new harbor freight puller. Then I realized I needed that hole LOL. I drilled a new one beside it and used the harbor freight bolts included with the puller to self-tap. Surprisingly that worked. The pulley came off with a big pop. I think the semi sheared key was holding it abnormally tight. The flywheel looks ok, but I am nervous about having a new hole in it. I don't want it to explode. This is a mower from the free pile that I am trying to sell for profit. If I sell someone a grenade flywheel I might get in trouble. Anyway, it was filthy, so I cleaned the block really good, and reinstalled the flywheel with a new key. Gapped the ignition. Checked the plug. Cleaned the carb.
AAAnd it runs no better than before all of that. It's still better now that the blade is straight, but its not great. It isn't terrible though; The untrained ear wouldn't notice or care about the way it runs. But it's almost quieter than normal, a bit low on RPMS, and vibrates a bit. The oil was overfilled. I drained it a bit back to normal level. No change. Also, when I lift the mower off the ground, it makes a slight rattling noise from the engine somewhere. I don't know what that noise could be, because I had it torn down almost all the way and didn't see anything that would do that. I decided to take the head off and have a look around. Head bolt broke, there was one that was extremely tight on the bottom center. Valves are seating properly though, and cylinder walls look great. Not a crazy amount of carbon. Now I'm at a loss again, as to what the problem could be, just with a different mower this time. Maybe it's supposed to run this way? I also don't know what to do about the headbolt and the possibly dangerous flywheel. Although, I suppose that if the flywheel broke, it would have the shroud around it and probably wouldn't hurt anybody.
Any ideas? Thanks again!

Video of mower:
Side note. The front wheels are incredibly loose. Not the bolts, but the diameter of the wheel mount is way to big for axle. Either extremely worn or somebody put the wrong wheels on.

On some of the mowers with the newer Susa cup type starter. The handle has enough slack that will cause the starter pawls to come out enough to hit the inside of the starter cup when a downward pressure is applied to the handle. that could be your noise.

ILENGINE said:

On some of the mowers with the newer Susa cup type starter. The handle has enough slack that will cause the starter pawls to come out enough to hit the inside of the starter cup when a downward pressure is applied to the handle. that could be your noise.

Click to expand...

You know what I bet you're right. It does kinda sound like that's where the noise is from. So otherwise, it's pretty smooth but the engine of course still is running in a way I think ain't right. I't probably fine. Maybe I'll try runnin some seafoam through and adjusting the governor. Also the blade boss missing one of those little pieces may be an issue I need to address before I sell the mower. So I gotta check that, the wheels, flywheel, running rough, and a broken head bolt. These engines have like 8 bolts, if just one is broken, would it be a huge deal?

Depending which bolt is broken could create bigger issues than others, but one missing bolt will always have the potential for a head gasket leak.

IF you have a compressor then use the air hammer with a pry bar.
The x thousand blows a minute do much better job than a smack from a 4 lb hammer and far less likely to end up with a hole in the crankcase.
I have had that tool for better than 20 years. it came as part of the " + free tool kit " with the compressor and until I started working on mowers only ever used it to chop off a couple of nuts.
Now it gets used daily & is just about worn out and the hammers are going rusty

I do plan on getting some more tools in the near future - air hammer, pneumatic drill, compressor, torque wrench, tap/die set, new ratchet, maybe a welder one day, etc.

Anyway I drilled out the broken bolt yesterday to 5/16ths. I don't have a drill press, so it's not perfectly straight, but it should be good enough. The problem is, I do not know what to do now. I can't find any specs as to what the head bolt dimensions are, so I don't know what heli-coil kit to get. I considered trying to find a bigger bolt and tap some bigger threads and just use a bigger bolt too. But, I don't know a ton about how bolts/threads work, so I don't know what to look for. Any Ideas for this? Thanks!

TylerFrankel1 said:

I do plan on getting some more tools in the near future - air hammer, pneumatic drill, compressor, torque wrench, tap/die set, new ratchet, maybe a welder one day, etc.

Anyway I drilled out the broken bolt yesterday to 5/16ths. I don't have a drill press, so it's not perfectly straight, but it should be good enough. The problem is, I do not know what to do now. I can't find any specs as to what the head bolt dimensions are, so I don't know what heli-coil kit to get. I considered trying to find a bigger bolt and tap some bigger threads and just use a bigger bolt too. But, I don't know a ton about how bolts/threads work, so I don't know what to look for. Any Ideas for this? Thanks!

Click to expand...

Take the drill bit you used to the parts store and tell them you need a heli coil set that will fit the hole you drilled with that bit. They'll probably just hand you what you need.

If you are going to use a Heli-Coil and do it the right way, you can just guess at the drill size. Heli-Coils use a size specific drill to thread size. You need to purchase a kit which will include drill, tap, insertion tool and inserts. Using the wrong drill could easily lead to more problems.

Rivets said:

If you are going to use a Heli-Coil and do it the right way, you can just guess at the drill size. Heli-Coils use a size specific drill to thread size. You need to purchase a kit which will include drill, tap, insertion tool and inserts. Using the wrong drill could easily lead to more problems.

Click to expand...

Well I finally bought a tap/die and a torque wrench.
Instead of Helicoil I went a lazier route and decided to just tap it with 3/8 threads and use a 3/8 bolt with a lock washer I bought at Home Depot. That worked but I was stupid and rounded off the bolt by using a metric socket. So now I have to get some of those special sockets that can take off rounded bolts, and start over. I also managed to break another bolt off when practicing with the torque wrench. I think someone overheated this engine and made the bolts brittle. I'll be drilling and tapping another hole I suppose!

I don't see any drawback to using 3/8 bolts except that they aren't the same size as the old ones so it's less convenient to work with anyway.

I've also been a bit nervous about the flyhweel since I put a second hole in it. I don't think it would hurt anyone though since it's surrounded by the cooling shroud. I don't know though.