BUDFAN8

you may also want to check for rust on the fly wheel. there is a magnetic part on it that has to be clean to work properly.

newnewbie is also correct if the keyway is sheered or bent it causes it to be out of time. if everything looks good then it will probley be your magneto coil. and if there is a way of checking it i havent heard of it but a local small engine shop may know how.