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Briggs & Stratton 31C707 will not start

Smokey I mowed part of the lawn a few days ago, put the lawn mower away as usual. Went to finish mowing today and it won't start. It backfires thru the exhaust a few times then the carb a couple of times. I checked the flywheel sheer pin and it's ok. Took the valve cover off and found the exhaust valve had a quarter inch gap. Adjusted the valves and checked cam timing and it's ok also. Cleaned and reinstalled the spark plug, poured a little gas in the carb and tried to start it. Same thing. Back firing thru the exhaust a few times then the carb a couple of times. Even tried a small shot of ether. I've got air, fuel, spark, and timing. What am I missing? I didn't know where to post this.

rcbe
Re: Briggs & Stratton 31C707 will not start

description still indicates timing as problem, imho. Look at att info and then recheck flywheel key. If you cannot obtain 110 ft lb of torque, best take machine to shop.

Smokey I can't read the image, too small. I agree, it seems like it's firing way late. The flywheel key is dead on. Going by the flywheel it's firing near 10 degrees before TDC. The sound from the exhaust is more like fut fut fut fut and the exhaust pipe is hot to the touch. I'm baffled. I'll check it out all over again tomorrow. Thank you.
Smokey Checked it out again this morning. I opened the lash on the intake valve to take the compression release out of the mix. I found the engine has no compression. I can spin it over with my hand on the flywheel. Next step is to pull the head to see if it's valves or rings.
Smokey Well I found the problem. There's a hole in the piston. Thanks for your help. Smokey
rcbe glad you found the prob - but bummer on the piston hole.
Might be interesting as to what caused that hole, Smokey... we may still just be looking at the symptom - not the cause.



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