If none of that works, then since you've been running it rich for a while or
off and on, you may be dealing with the wrong end and need to torch or scrape
the carbon off the muffler. Very uncommon for 4-cycles to build-up enough to
choke-out the engine, but definitely worth removal from the checklist.



the timing could also be off..

did you hit something with the blade?

do you know about the "shear key"

mark