Violent Recoil on Wheeled trimmer

[Fish]

I would also pull the head and decarbon, excess carbon will raise the compression ratio a lot.

 

[Bat57]

Update: I pulled the head off and took the cover off the valves. I checked the valve clearance with the piston 1/4 past TDC on the combustion stroke. the Intake clearance was .005 and the Exhaust was .007 and neither vale would turn or move on head. So i think they are good. The top of the piston had a lot of carbon buildup as well as the inside of the head. So i cleaned both real good and am about to put it back together unless some else has an idea.

 

[Bat57]

I would also pull the head and decarbon, excess carbon will raise the compression ratio a lot.

Did that and there was a lot of buildup. checked valve lash both were within specs. Intake 5 and Exhaust 7, (thousands)

 

[Hammermechanicman]

Built this string trimmer out of a push mower about 20 years ago. Has the lightweight aluminum flywheel.

 

[Bat57]

View attachment 52983
Built this string trimmer out of a push mower about 20 years ago. Has the lightweight aluminum flywheel.

looks like it will do the job.

 

[Fish]

No, pop the head back on and see what happens.

Was the filter real dirty?

 

[Fish]

Can you take a pic of the valves and cylinder wall?

Was the carbon powdery/chalky, or black and oily?

 

[Bat57]

I assume you have the engine on a push mower with a blade on it. Things that can cause kick back are a partial sheard key and a loose blade. Valves in a briggs L head engine vary rarely need the lash adjusted unless valves are worked on. If the engine does not have a blade on it will start and run but can kick back trying to start and sometimes have a rough idle. The blade augments the lighter flywheel on mush mowers.

Sorry it has taken so long to get back with you. Once I put the adapter on the crankshaft and installed the new belt after checking everything else the motor started and there was no bad recoil. thanks for your help.

 

[Bat57]

Can you take a pic of the valves and cylinder wall?

Was the carbon powdery/chalky, or black and oily?

Hi, it seems the engine was fine, the problem was that without the adapter on the crankshaft and the operating belt installed it would recoil bad. Once those where installed it didn't recoil badly. Thanks for your help. Sorry for taking so long to get back with you.