6.5 duraforce

[Fireman 123]

I have a 6.5 HP Duraforce powered mower that I have been going thru and tuning up. I've taken apart the carb and cleaned it, and changed the spark plug.
After buying it ($20) I brought it home and started it, but it had a substantial sputter, and spit old gas out of the above deck muffler.
Today, after cleaning and putting the carb back on, the engine run smooth, but still an exhaust sputter. I took the cover off the exhaust tube housing under the deck and a bunch of old gas spilled out of it. The tube itself had a little carbon build up, but wasn't blocked any.
After cleaning that mess up and putting the tube back and cover on, it still has the sputter and smokes some. I always use LB oil 32/1. I think all of this is pointing to bad rings, hence the smoke, and gas getting by into the exhaust. If there's anyone that can lend any expertise I'd appreciate it.

 

[Two-Stroke]

I wish I could give you a good answer but all I can say is that if the rings are bad enough to produce a symptom like that then the compression should also be low -- does it seem to have low compression?

I would eliminate all other possibilities before getting into major engine surgery (rings, pistons, bearings) and keep in mind that you probably want a certain percentage of your mower fleet to be "parts mowers". It makes sense economically given the price of parts vs the price of a used mower. :wink:

 

[Fireman 123]

Thanks. It seems to have really good compression. I believed I've narrowed it down to a carb issue.

 

[Two-Stroke]

Thanks. It seems to have really good compression. I believed I've narrowed it down to a carb issue.

That's good news. BTW, what's the model number? I'm also curious about whether that engine (Duraforce) is the same series as my 1994 model 10415.

 

[Fireman 123]

Yours has the F engine which are the smoothest running one IMO. After watching some you tube vids, I've noticed about all of the Duraforce mowers run just like mine. It's highly recommended to put an in-line fuel shutoff, which I did today. The needle and seat prob need replaced to fix the flooding issue. Lots of Duraforce owners have the same issue of raw fuel being blown out of the exhaust on start-up. Lawn Boy must've gotten lazy in the last years by not having a fuel petcock like all the older mowers. It did however clean up pretty good.

 

[Fireman 123]

It's a 10323. Made back in y2k lol.

 

[Two-Stroke]

Yours has the F engine which are the smoothest running one IMO. After watching some you tube vids, I've noticed about all of the Duraforce mowers run just like mine. It's highly recommended to put an in-line fuel shutoff, which I did today. The needle and seat prob need replaced to fix the flooding issue. Lots of Duraforce owners have the same issue of raw fuel being blown out of the exhaust on start-up. Lawn Boy must've gotten lazy in the last years by not having a fuel petcock like all the older mowers. It did however clean up pretty good.

The mower looks really good. That's a big plus if you plan to sell it.

I installed a fuel valve on a Suzuki-powered Toro (which is one of my favorite mowers). I think it will prevent a lot of problems resulting from fuel slowly seeping into the carb and turning into some variety of gunk.

I've also added in-line fuel filters to several Lawn-Boys even though they have the screen filter in the tank.

I've heard that the Duraforce engine wasn't made by Outboard Marine, while the earlier LB engines were.

 

[Fireman 123]

This is my first Duraforce. I'm not exactly sure who made these engines either. I've ordered a new needle & seat kit for it.