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

[bt3]

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

It probably helps that here in Michigan it only gets used for about 6-months out-of-the-year and in my case, once a week where it only gets started once and run for about a half hour. I'm sure the minimal use helps to extend it's life.

It got me curious, so I looked it up in the Service Manual and in Lawn-Boy's own words, it's "about 5 degrees" BTDC and "about 28 degrees" BTDC at "about 800 RPM". You've got a pretty good memory.

Not bad! :thumbsup:

 

[beg]

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

Dont buy a carb kit unless you need it also you have to assemble it as it comes in pieces.when you take your carb off look for warpage on the flanges.if they are warped you need the carb kit.if the flanges are warped the inner carb passages most likely are too.as far as ebay goes I have not had a bad expierence with buying parts for Lawnboys and I have purchased a lot of coils and fuel shutoff valves.I did buy a carb kit and put it together following some great instructions and pics on "{my Tractor Forum '[ if you plan to build up a carb study up on the jet drilling process.It make a world of difference on how the duraforce motor runs as it was developed to pass epa standards running a little on the lean side. You will have to purchase a micro drill bit set but they are cheap on ebay here is a pic of my gold series push n go I picked up for 20.00 needed a coil and carb cleaning

 

[dewguy1999]

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

Dont buy a carb kit unless you need it also you have to assemble it as it comes in pieces.when you take your carb off look for warpage on the flanges.if they are warped you need the carb kit.if the flanges are warped the inner carb passages most likely are too.as far as ebay goes I have not had a bad expierence with buying parts for Lawnboys and I have purchased a lot of coils and fuel shutoff valves.I did buy a carb kit and put it together following some great instructions and pics on "{my Tractor Forum '[ if you plan to build up a carb study up on the jet drilling process.It make a world of difference on how the duraforce motor runs as it was developed to pass epa standards running a little on the lean side. You will have to purchase a micro drill bit set but they are cheap on ebay here is a pic of my gold series push n go I picked up for 20.00 needed a coil and carb cleaningView attachment 23160

Thanks for all the advice on the "rebuild kit". I read one thread, I think it might have been on MyTractorForum.com where the guy got the kit and built it and ended up with the new carb surging the same as his old one. That's the kind of luck I would have. Thankfully my Lawn-Boy doesn't surge and I'm hoping that if I end up having to do anything with the carb that it doesn't start surging when I'm done.

I received the CDI today and if all goes to plan I'll get everything installed tomorrow and be back in business. I hope it's not all for naught as my lawn really needs a mowing.

Nice looking Gold Series and it looks like you got a great deal on that mower getting it for only $20.

 

[bt3]

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

Keep us posted Please, Dewguy.

Hope you get that lawn done and all goes well.

 

[dewguy1999]

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

Keep us posted Please, Dewguy.

Hope you get that lawn done and all goes well.

Well I installed the new fuel line, 90 degree shut off valve and the CDI today. I also cleaned the spark plug and some more of the oily grime from places that I couldn't get to the other day and scraped out the underside of the deck and the bag chute.

Filled it with the last of the gas I bought in May. I turned on the valve and and pulled the cord (without priming it) and it tried to start but died out. Gave it another pull (without priming) and it didn't start. So, I gave it one press of the primer and it stated on the first pull. I'm cautiously optimistic that it's going to continue to do so. Fingers crossed. With the rear bagger chute on the mower the valves not in the best place for accessibility but I've got small hands so I can get to it.

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 a sound. I don't really know what I'm talking about, but I'm going to say it seemed to be missing. When I moved the throttle down to a slower speed I could get it to stop smoking and missing, if I increased the speed it started smoking and missing, 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.

When I finished the entire yard I lowered it a notch (I had raised for the long grass) and re-mowed the front lawn. While doing the re-mow I managed to come down on my driveway apron and scalped the corner of the grass and caused the mower to stall. I thought I was done then because I've never had much luck getting it to start again when the engine is hot, but I tried and it started and I was able to finish the re-mow.

I'm hoping that you will tell me that my new problem is caused by the stale gas. I'll have to get gas before I mow again and hopefully doing so will fix this. If I'm just grasping at straws with this theory please let me know.

Thanks.

 

[bt3]

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

Nice job on that shutoff valve. My LB has one on the tank factory installed, and I do use it.

OK, Smoke and missing on full throttle.

My guess would be stale gas, Carb issue or a bad CDI offset degree for high speed. The CDI has two magnets as you know. One at about 5 degrees for starting and one at about 38 degrees for high speed. If the CDI was not installed and gapped correctly (I use a business card as a gap meter) or if it has some issue from manufacture, high speed operation can cause this issue as the offset (before top dead center) is not quite enough when you get beyond, say, 3,000 rpm. The carb adjustments (jets) have to be tuned correctly as well for correct high speed ops.

But don't despair. Try new gas first! Lots of guys will tell you not to waste your money on a higher grade of gas , but I run Mid grade (89 octane) gas in my small motors. Not premium and not regular. Mid grade. I get better ignition and results. Learned this lesson when I had a 2 stroke motorcycle and from running LawnBoy for 9 years now. Mid grade makes a difference in the long haul. My opinion. Let us know how you make out with the fresh gas. Tackle that first. Then we'll see how the mower does at high RPM.

 

[dewguy1999]

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

Nice job on that shutoff valve. My LB has one on the tank factory installed, and I do use it.

OK, Smoke and missing on full throttle.

My guess would be stale gas, Carb issue or a bad CDI offset degree for high speed. The CDI has two magnets as you know. One at about 5 degrees for starting and one at about 38 degrees for high speed. If the CDI was not installed and gapped correctly (I use a business card as a gap meter) or if it has some issue from manufacture, high speed operation can cause this issue as the offset (before top dead center) is not quite enough when you get beyond, say, 3,000 rpm. The carb adjustments (jets) have to be tuned correctly as well for correct high speed ops.

But don't despair. Try new gas first! Lots of guys will tell you not to waste your money on a higher grade of gas , but I run Mid grade (89 octane) gas in my small motors. Not premium and not regular. Mid grade. I get better ignition and results. Learned this lesson when I had a 2 stroke motorcycle and from running LawnBoy for 9 years now. Mid grade makes a difference in the long haul. My opinion. Let us know how you make out with the fresh gas. Tackle that first. Then we'll see how the mower does at high RPM.

I used a business card to install the new CDI, as a matter of fact it was the same one I used 7-years ago when I installed the last replacement, so I think I'm good on the gap. It started smoking and missing after I had been mowing for about 15-20 minutes (I think) and not until I hit the dip (which I suppose could be a coincidence) does that make sense for it being a bad CDI?

The mower has about a half a tank of stale gas now, and I'm leaning towards getting the no ethanol gas (90 octane I think) from the local marina when I get fresh, so that should be better for it on many different levels from what I understand.

 

[bt3]

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

I used a business card to install the new CDI, as a matter of fact it was the same one I used 7-years ago when I installed the last replacement, so I think I'm good on the gap. It started smoking and missing after I had been mowing for about 15-20 minutes (I think) and not until I hit the dip (which I suppose could be a coincidence) does that make sense for it being a bad CDI?

The mower has about a half a tank of stale gas now, and I'm leaning towards getting the no ethanol gas (90 octane I think) from the local marina when I get fresh, so that should be better for it on many different levels from what I understand.

Yes. Let's cross one bridge at a time. Get the 90 octane no Ethanol, drain the stale gas. Run the fresh gas mix for 30 minutes mowing (might as well get some use out it and mow again cross hatching what you did today). I am hoping that the missing and smoke does not come back at high RPM.

I doubt the "Dip" made any difference, unless it somehow knocked a governor spring loose or something like that. I suppose a governor out of adjustment or with a spring loose and allowing the mower to be pushed beyond limits of RPM that the CDI can sustain by the offset would cause an issue. This is really speculating now. Another speculation would be a piece of carbon was bumped out of the ignition chamber and lodged in the exhaust port. Highly speculative. I'd think a carb issue first.

Gas first! Then we'll see about the rest if the gas does not cure the issue outright!

 

[dewguy1999]

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

Yes. Let's cross one bridge at a time. Get the 90 octane no Ethanol, drain the stale gas. Run the fresh gas mix for 30 minutes mowing (might as well get some use out it and mow again cross hatching what you did today). I am hoping that the missing and smoke does not come back at high RPM.

I doubt the "Dip" made any difference, unless it somehow knocked a governor spring loose or something like that. I suppose a governor out of adjustment and allowing the pushing the mower beyond limits of RPM that the CDI can sustain would cause an issue. This is really speculating now. Another speculation would be a piece of carbon was bumped out of the ignition chamber and lodged in the exhaust port. Highly speculative. I'd think a carb issue first.

Gas first! Then we'll see about the rest if the gas does not cure the issue outright!

Gas first sounds like a good plan. It probably won't be for a few days or more but I'll let everyone know when I've tried that.

When I was almost done mowing today, I turned off the valve and then continued cutting until it ran out of gas, is that the way I should do that or should I have tried to restart it?

 

[bt3]

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

Gas first sounds like a good plan. It probably won't be for a few days or more but I'll let everyone know when I've tried that.

When I was almost done mowing today, I turned off the valve and then continued cutting until it ran out of gas, is that the way I should do that or should I have tried to restart it?

No sir. Running it out of gas is fine. When it stops you are done. I typically throttle the mower back to low speed when I'm done cutting (mowers cool better when they are run on low speed for a while before shutting off) and let it run parked in front of the garage, cut the fuel and let it wind down on its own. Then I park it until next time. Turn on the fuel, wait a few minutes for the bowl to fill, and pull the starter. :thumbsup:

I'll be looking forward to your response!