Need some advise

[spareparts]

look under the flywheel for metal shavings, I've seen stator bolts back out and cause contact with teh flywheel. I freind of mine had a 130 Yamaha that knocked from the first time I met him, it kept on for about three years, He started runnign ringfree with his gas, after about two tank fulls, the kknock went away. I don't have a clue wat it could be, but its had three more seasons on it since