you might have a sticky piston ring the are common if using poor oil or mix ratio to rich
dave
May 2005
could be the plug, but i assume you mean no spark at all. try changing the plug anyway. most likely its the magneto, which generates the spark. behind or next to the flywheel is an electric circuit, usually on a U shaped bit of iron with 2 coils, 1 on each leg. there is a switch like object, try cleaning the contacts thoroughly. this is what causes the spark. also, check for burnt wires.
steve
May 2005
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