Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

[Phototone]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

The video indicates a very common surge issue with this model LawnBoy under no load or light load. Does it clear up when you get into the grass? When you put the engine under some load? If it does, then it is the common idle surge for this mower. If so, it can be fixed, if you so desire. Google for LawnBoy Duraforce Surge.

 

[bt3]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

I see not only surging but mis-firing. I have a hunch the apparent surging is driven by the skipping and hitting issue.

 

[dewguy1999]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

OK, I'm up to date with you again. Thanks for the recap.

Did the skipping issue start AFTER you installed the shutoff valve? Just a hunch that perhaps the valve is not flowing well and you are leaning the fuel flow somehow with it. That's a longshot. I'm just speculating outside the normal issues box.

Drain ALL of the old gas before you put new in. You want fresh gas from the getgo to diagnose if the gas is curing the problem. It is even possible there was a little moisture (water) in the old gas. I always run a few cap fulls of HEET Isopropyl (in the RED BOTTLE - NEVER the Ethyl in the YELLOW Bottle in a 2 stroke) to take water out of the gas. Heet also has a mild cleaner in it to help with carb cleaning on-going. I'm just going overboard here to help you diagnose ALL issues.

The Carb may be dirty, the float may be stuck and/or the needle valve may not be working properly. However, if these issues JUST started, the carb is the last thing I'd go to for issue. Servicing a carb on a LawnBoy 2 stroke is a walk in the park with a Cocker Spaniel! Really fairly easy. Lots of Youtube videos to help you out. But let's not go there yet.

Did anything happen to the air filter? Is the filter clean and lightly oiled?

Replace that plug. They are cheap as you know. I've heard issues lately with plugs failing quickly or right out of the box. For what it costs, even if it's not the plug, you can always use a spare hanging around. I've got a few. Why not.

In my motor, there is a small insert screen in the fuel line right where the fuel line connects to the carb. If your Duraforce has one, take it out and clean it with carb spray. I'd take that opportunity to carb cleaner spray the fuel inlet port. I'd spray a little in the air intake port. Can't hurt. Just don't overdo it.

That's about it. You've got some homework there and that should keep you busy over the weekend. I'll be on here all weekend if something crops up!

On Wednesday, I got about 3/4 of the front/side yard cut when I went over a low spot next to my neighbor's fence and the mower started smoking and making those sounds. This was after mowing for about 20-30 minutes I guess. When I moved the throttle down to a slower speed I could get it to stop smoking and making the sounds, but if I increased the speed it started smoking and making the sound, so, I continued mowing at the slower speed. I don't usually run it wide open, but I did today because the grass was so long. So the short answer is yes, it started after I replaced the fuel line, shut-off valve and CDI, but not immediately. When I mowed yesterday morning (Friday) it was running like this from the get go.

I know that draining the old gas is probably what's best, but I don't really know what to do with it. If I can find something to put it in and store it, I'll drain it. Before anyone suggest that I pour it somewhere or let it sit and evaporate, I'll tell you that I'm not going to that. I forgot about Heet, my Dad used to put that in our cars in the winter when I was a kid. As an FYI, according to this site Does your gas additive contain alcohol and/or water absorbing ingredients? Heet contains alcohol and you as said absorbs water, so it may be doing more harm than good if alcohol (ethanol) is as bad on 2-cycle engines as they say.

I cleaned and oiled the air filter on August 18th, it was in good shape and as far as I know there isn't anything wrong with it.

As far as I know the only filters in the fuel system on a Duraforce are a permanent one in the fuel tank above the fuel outlet and a filter in the carb on the high speed jet/nozzle.

The video indicates a very common surge issue with this model LawnBoy under no load or light load. Does it clear up when you get into the grass? When you put the engine under some load? If it does, then it is the common idle surge for this mower. If so, it can be fixed, if you so desire. Google for LawnBoy Duraforce Surge.

The first I noticed the surging was when it was sitting there while I made the video, but it may have been doing it under load as well and I didn't notice it because of the other sounds and the fact that it started suddenly. Hopefully when I get some fresh gas and cut the grass during the next week or so, I'll be able to tell you that all is well and the problem is gone, but if not I will make sure to notice if it's still surging under load. I've never had a problem with it surging before so I hope this doesn't continue.

I see not only surging but mis-firing. I have a hunch the apparent surging is driven by the skipping and hitting issue.

There's definitely a misfire or something going on there and when it does it the mower "shakes".

 

[bt3]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

It is damn odd that these issues started AFTER your tune-up, but sometimes it DOES happen... by COINCIDENCE. Perhaps a piece of something got knocked loose and found its way to a jet and clogged it. Anything is possible with a mechanical device.

It sure sounds like a high speed jet problem. I don't have experience with your exact Carb, but I do know that a lot of issues can be cured with Seafoam.

OK, JUST A THOUGHT. I have two suggestions if you can't clear the issue as we previously addressed.

1.) Put some Seafoam in your tank (especially if you are not going to drain the old gas) and run it for a while. See if the high speed skipping quits. It may take a full tank to work for you. I'd run two full tanks with Seafoam. Don't go overboard with the mix. Perhaps 1 to 2 oz per tank full. Seafoam recommends 2 oz per gallon in 2 cycle engines. You don't want to lean out your gas/oil mix too much, but you do want enough to make sure things get clean.

2.) If #1 does not work, Pull the Carb and soak the Carb for 24 hours in a bowl of straight Seafoam. Shake it around when submerged in Seafoam to make sure it gets in to all the nooks and crannies and all the JETS. Reinstall and see if this helped.


I have a hunch that if it is a gummed or clogged jet, running Seafoam from your tank just may clear it. I recommend this to folks that are not comfortable tearing the carb completely apart. Removing a bowl and changing a float and needle valve is incredibly simple. I'd remove the bowl and the float and the needle and then soak the remaining carb body in Seafoam. While I was at it, I'd replace the float and needle. The kits are plentiful and cheap.


Regarding HEET, yes, it has Isopropyl Alcohol and cleaner solvents in it, but is is approved for 2 stroke engines. It will hot harm the engine or carb. It will clean out water droplets and cleans the jets on-going but not as well as Seafoam IMO. Yet, it's inexpensive and works good as a "preventative maintenance" additive. I run about 2 OZ of Heet per 2 gallons of gas/oil mix for maintenance. Same with Seafoam if you want, but with Seafoam they recommend 4 oz per 2 gallons. They both do about the same thing, but if I really want to "Clean" I use Seafoam.

There are two types of HEET additive. A red and a yellow bottle. NEVER use the yellow in a 2 cycle. That's Ethyl and it is very bad. The red bottle is Isopropyl and that is fine for 2 cycle hen used in proper amounts.

 

[dewguy1999]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

It is damn odd that these issues started AFTER your tune-up, but sometimes it DOES happen... by COINCIDENCE. Perhaps a piece of something got knocked loose and found its way to a jet and clogged it. Anything is possible with a mechanical device.

It sure sounds like a high speed jet problem. I don't have experience with your exact Carb, but I do know that a lot of issues can be cured with Seafoam.

OK, JUST A THOUGHT. I have two suggestions if you can't clear the issue as we previously addressed.

1.) Put some Seafoam in your tank (especially if you are not going to drain the old gas) and run it for a while. See if the high speed skipping quits. It may take a full tank to work for you. I'd run two full tanks with Seafoam. Don't go overboard with the mix. Perhaps 1 to 2 oz per tank full. Seafoam recommends 2 oz per gallon in 2 cycle engines. You don't want to lean out your gas/oil mix too much, but you do want enough to make sure things get clean.

2.) If #1 does not work, Pull the Carb and soak the Carb for 24 hours in a bowl of straight Seafoam. Shake it around when submerged in Seafoam to make sure it gets in to all the nooks and crannies and all the JETS. Reinstall and see if this helped.


I have a hunch that if it is a gummed or clogged jet, running Seafoam from your tank just may clear it. I recommend this to folks that are not comfortable tearing the carb completely apart. Removing a bowl and changing a float and needle valve is incredibly simple. I'd remove the bowl and the float and the needle and then soak the remaining carb body in Seafoam. While I was at it, I'd replace the float and needle. The kits are plentiful and cheap.


Regarding HEET, yes, it has Isopropyl Alcohol and cleaner solvents in it, but is is approved for 2 stroke engines. It will hot harm the engine or carb. It will clean out water droplets and cleans the jets on-going but not as well as Seafoam IMO. Yet, it's inexpensive and works good as a "preventative maintenance" additive. I run about 2 OZ of Heet per 2 gallons of gas/oil mix for maintenance. Same with Seafoam if you want, but with Seafoam they recommend 4 oz per 2 gallons. They both do about the same thing, but if I really want to "Clean" I use Seafoam.

There are two types of HEET additive. A red and a yellow bottle. NEVER use the yellow in a 2 cycle. That's Ethyl and it is very bad. The red bottle is Isopropyl and that is fine for 2 cycle hen used in proper amounts.

I have to say that all of this is really messing with my mind. Over and over I read that ethanol in gas is a bad thing and that we should be using ethanol free gas, but then I read recommendations for products like Heet and Seafoam, both of which contain isopropyl alcohol. Since the gas I've been using for how many years (I don't know) contains ethanol, shouldn't it have done what the Heet and Seafoam are claiming to do? I'm not trying to be difficult here, but I just don't get it. :confused2:

 

[bt3]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

I have to say that all of this is really messing with my mind. Over and over I read that ethanol in gas is a bad thing and that we should be using ethanol free gas, but then I read recommendations for products like Heet and Seafoam, both of which contain isopropyl alcohol. Since the gas I've been using for how many years (I don't know) contains ethanol, shouldn't it have done what the Heet and Seafoam are claiming to do? I'm not trying to be difficult here, but I just don't get it. :confused2:

Ethanol and Isoproply are two TOTALLY different chemical compounds. Over time Ethanol can contribute to problems in a 2 stroke, and pure Ethyl Alcohol (yellow Bottle of Heet) can cause gumming quickly.

ISOPROPYL alcohol simply combines with water, then mixes with gas and burns it up in combustion. No harm, no foul to a 2 stroke.

Adding small amounts of Red HEET (Isopropyl) to your 2 stroke will cause no issues. All it will do is help clean and take out moisture. Same with Seafoam. In small quantities it is safe. It's not just alcohol to combine with water, it's a fuel system cleaner. So no, Ethanol via your pump will not molecularly do the same thing as Heet or Seafoam. Ethanol tends to gum up a 2 stroke over time, Isoproply does not. Also, there are no CLEANING compounds added to Ethanol in gas. Seafoam and Heet RED bottle have carb and injector cleaners.

All this being said, we are all just giving you suggestions based on what we see and hear and read. The mower is missing and therefore surging. I believe the surging is being caused by the hit and miss cycle. This new behavior is AFTER your tune-up and adding a shutoff valve. Anything is possible. A small piece of something may have dislodged when you cut in the valve or a tiny piece of the valve may have got into the fuel flow and is now partially clogging a jet. There may be an issue with float, or needle, or jet adjustment. There may be an issue with spark. The new CDI may be fine at lower RPM but bad at high RPM. There may be an issue with a crank seal, or a reed, however, with no backfire, I am inclined to rule this out. There may be an issue with the spark plug. The exhaust port, or reed valves.

You have to go back to my previous post. These are what I would do in order;

First: FRESH FUEL!

Second: NEW SPARK PLUG. For a few bucks, replace it if it is not new.

Third: MAGNETO AND FLYWHEEL. Is there RUST on the flywheel magnets? Sand it off. May not be your problem but if it started when you put the new CDI on, then this is highly suspect! Put on that old CDI and try it.

Forth: CARB ISSUE. Bad adjustment or poor venturi flow through a jet, bad float or needle valve.

IF it ends up being a Carb issue, I thought I'd give you a quick way to try and clean the carb without total disassembly. The Seafoam trick sometimes works in the gas, and if not, usually works if you soak the carb in seafoam overnight.

WE are going to hope that it is not a Reed Valve (easy to check when the carb is off) or a crank seal problem. And we assume your Governor is working easily and freely and that the wind vane is traveling well.

I found this vid on Youtube for your mower on carb cleaning to fix hunting and surging issues. Not specifically your "missing" issue but a nice tutorial for taking off and cleaning the carb on a Duraforce, including bowl removal and float check.

https://www.youtube.com/watch?v=n5sYTvYQpI8

 

[dewguy1999]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

Ethanol and Isoproply are two TOTALLY different chemical compounds. Over time Ethanol can contribute to problems in a 2 stroke, and pure Ethyl Alcohol (yellow Bottle of Heet) can cause gumming quickly.

ISOPROPYL alcohol simply combines with water, then mixes with gas and burns it up in combustion. No harm, no foul to a 2 stroke.

Adding small amounts of Red HEET (Isopropyl) to your 2 stroke will cause no issues. All it will do is help clean and take out moisture. Same with Seafoam. In small quantities it is safe. It's not just alcohol to combine with water, it's a fuel system cleaner. So no, Ethanol via your pump will not molecularly do the same thing as Heet or Seafoam. Ethanol tends to gum up a 2 stroke over time, Isoproply does not. Also, there are no CLEANING compounds added to Ethanol in gas. Seafoam and Heet RED bottle have carb and injector cleaners.

All this being said, we are all just giving you suggestions based on what we see and hear and read. The mower is missing and therefore surging. I believe the surging is being caused by the hit and miss cycle. This new behavior is AFTER your tune-up and adding a shutoff valve. Anything is possible. A small piece of something may have dislodged when you cut in the valve or a tiny piece of the valve may have got into the fuel flow and is now partially clogging a jet. There may be an issue with float, or needle, or jet adjustment. There may be an issue with spark. The new CDI may be fine at lower RPM but bad at high RPM. There may be an issue with a crank seal, or a reed, however, with no backfire, I am inclined to rule this out. There may be an issue with the spark plug. The exhaust port, or reed valves.

You have to go back to my previous post. These are what I would do in order;

First: FRESH FUEL!

Second: NEW SPARK PLUG. For a few bucks, replace it if it is not new.

Third: MAGNETO AND FLYWHEEL. Is there RUST on the flywheel magnets? Sand it off. May not be your problem but if it started when you put the new CDI on, then this is highly suspect! Put on that old CDI and try it.

Forth: CARB ISSUE. Bad adjustment or poor venturi flow through a jet, bad float or needle valve.

IF it ends up being a Carb issue, I thought I'd give you a quick way to try and clean the carb without total disassembly. The Seafoam trick sometimes works in the gas, and if not, usually works if you soak the carb in seafoam overnight.

WE are going to hope that it is not a Reed Valve (easy to check when the carb is off) or a crank seal problem. And we assume your Governor is working easily and freely and that the wind vane is traveling well.

I found this vid on Youtube for your mower on carb cleaning to fix hunting and surging issues. Not specifically your "missing" issue but a nice tutorial for taking off and cleaning the carb on a Duraforce, including bowl removal and float check.

https://www.youtube.com/watch?v=n5sYTvYQpI8

I've been having internet problems and having an awful time getting this site to load for the last three days and haven't been able to read or reply since sometime yesterday, hopefully it will be working better now.

Thank you for the explanation of isopropyl alcohol versus ethanol as this is all very confusing to someone like me. Since 2004 I've been using BP gas in my mower (which may or may not be E10 since Michigan doesn't require labeling) and according to their website:

All three grades of new BP gasoline with Invigorate have a unique formula that, with continuous use, helps clean critical engine parts and protects against deposits, corrosion and sludge formation. Results include cleaner engines that minimize exhaust emissions, experience smoother acceleration with less hesitation, and provide restored fuel economy. ​

I don't know how long their gas has had "Invigorate", but it sounds to me like it does have some cleaning properties. I imagine that whether or not that is sufficient could be subject to debate and it doesn't cover the removal of water like Heet, etc. but it might help in the long run.

I appreciate all your help and recommendations/suggestions.

Like I mentioned in my first message here, I don't really have any experience with internal combustion engines (2-cycle or otherwise). Until I downloaded the Service Manual I didn't even know where the carburetor was on my Lawn-Boy. When we have car problems we take our car to a mechanic as I have absolutely no interest in working on cars. Over the years I've heard how easy Lawn-Boy's are to work on and if it's something that can be done step by step that has "fixed" results like changing the plug, cleaning/oiling the air filter, replacing the CDI or replacing the fuel line and adding a shut-off valve, I feel I can handle it and I have.

The whole carburetor rebuilding I feel differently about, not because I couldn't take it apart, I could do that, but putting everything back "just right" so it works the way it's supposed to is "too variable" to me and I'm not sure I want to try. I'm sure that for those of you that do this kind of thing regularly that it's a "piece of cake" but for someone who's never done it before it can be a lot to take on.

I'm becoming weary of the problems with my Lawn-Boy as they've been ongoing since the early part of July and as much as I like my Lawn-Boy I'm thinking more and more about getting a new mower instead while I can find something on fall closeout. I haven't ruled out doing more work on the Lawn-Boy yet and I might try some of the other things I just don't know right now for sure as I'm rather frustrated by it. If/when I try something else I'll be sure to let you know.

 

[bt3]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

Dewguy, I understand the frustration. 2 stroke small motors tend to be more finickey than 4 stroke. 2 stroke need good compression, a decent spark, the right fuel mix with fresh fuel, working Reed valves, a well adjusted carb, tight crank seals and a CLEAR exhaust route. They don't tolerate certain things like plugged exhaust very well.

On the flipside they are easy to work on, durable, and you don't have to worry about crankcase oil and seizing as long as you mix the 2 stroke oil correctly. They have way more HP per weight ratio and when they do run, they run like a bull with it's butt on fire. Nothing stops them.

I had to think back quite a few years ago, but I did have a problem a little like yours. And the problem was fuel starvation via the inline shutoff valve. It was partially clogged and trickling fuel rather than flowing it and the mower would surge, sputter and skip. I replaced the valve and all was good. Since your problems started when you put the inline valve in, did you monitor fuel flow through the valve? open it and let fuel run into a pan or jug. make sure it is flowing well. No restriction. No plugged vent hole in your gas cap.

Just a thought.

My previous emails covered all other bases pretty well I think. That Duraforce is one hellava machine. Hope you get it back to where you are happy with it. Perhaps there is a local guy near you that repairs small motors like Chain Saws so that has 2 stroke experience? Maybe he could help you for a nominal fee.

Keep us posted.

 

[dewguy1999]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

Dewguy, I understand the frustration. 2 stroke small motors tend to be more finickey than 4 stroke. 2 stroke need good compression, a decent spark, the right fuel mix with fresh fuel, working Reed valves, a well adjusted carb, tight crank seals and a CLEAR exhaust route. They don't tolerate certain things like plugged exhaust very well.

On the flipside they are easy to work on, durable, and you don't have to worry about crankcase oil and seizing as long as you mix the 2 stroke oil correctly. They have way more HP per weight ratio and when they do run, they run like a bull with it's butt on fire. Nothing stops them.

I had to think back quite a few years ago, but I did have a problem a little like yours. And the problem was fuel starvation via the inline shutoff valve. It was partially clogged and trickling fuel rather than flowing it and the mower would surge, sputter and skip. I replaced the valve and all was good. Since your problems started when you put the inline valve in, did you monitor fuel flow through the valve? open it and let fuel run into a pan or jug. make sure it is flowing well. No restriction. No plugged vent hole in your gas cap.

Just a thought.

My previous emails covered all other bases pretty well I think. That Duraforce is one hellava machine. Hope you get it back to where you are happy with it. Perhaps there is a local guy near you that repairs small motors like Chain Saws so that has 2 stroke experience? Maybe he could help you for a nominal fee.

Keep us posted.

Thanks for staying with me on this. I know how frustrating it can be when you're trying to help someone and they don't seem to be listening to what you're saying to them. I am listening and trying to understand all of this but it's not easy when you don't have the experience, it quickly overwhelms you.

I did not check fuel flow when I installed the new fuel line and shut-off valve, although before installing the shut-off valve I did blow on it in the open and closed position to see if it actually worked. I suppose it's possible that somewhere along the path from the tank to the carb it has become restricted, but I guess that would mean the blockage got past the built-in filter in the tank as it was running great for the first 20-30 minutes on Wednesday. Usually when I mow it get's wet around the vent hole in the gas cap and I believe it did on both Wednesday and Friday which I believe is an indication that's it's venting.

I'm not giving up on it yet as I will be getting some fresh gas in the next few days and will one way or another proceed from there. Updates to follow.

 

[beg]

Re: Help: Lawn-Boy 21" SilverPro Series, 10247, DuraForce (2-cycle) behaving badly

dont waste your time with iso propyl or sea foam.It wont do anything.you need to remove the carb and clean the jets at which time you should drill out the jets with a micro drill bit set there are a few posts on this forum referring to the procedure.its worth the time to do it.you will see a great improvement in you mowers performance.your air induction tube is a necessary part as they would not have put it there if it was not needed.the induction tube works like a ram air scoop on a car scavenging forced air from the flywheel.if you take the carb off remove it as a unit not in two pieces as the govenor spring is hooked to the carb body.yes its a PIA but if you pay attention to detail its not that hard.