I have a 10 hp Kohler (K241) under full throttle (and under load) it loses power and backfires out the exhaust.Last year I replaced a burnt exhaust valve, set the tappet clearance for the exhaust valve to .017” and intake valve to .008 (found a repair manual for this engine on Kohler’s website – was very helpful). I also noticed that the trigger module (it has a breakerless ignition) was about .250” from the flywheel, so I also set its clearance to .005”. That seemed to make it start much easier. Last fall it started to act up (backfire / losing power) and I put it away until this spring. I checked the clearance and it was still at .017 – thinking that the exhaust valve wasn’t closing I set it to .025 – that didn’t seem to make a difference. Thinking that it might have been running too lean I also tried adjusting the carburetor when it was warm and under load, but that didn’t help either. I’d really like to get this thing running great again since the old Allis cuts my lawn so much better than the neighbor’s new JD… What else should I be looking at?
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