Could it be air leak causing pre ignition. Had similar problem couple of years ago . Changed everything electrical / crank- top end & backfiring continued. Only thing NOT changed was the engine case which is early jet200 used for the first time.
First engine I ever gave up on( it's still on a shelf in the garage)
My thinking at the time was a hairline crack in the crankcase area, or not sealing properly on the inlet side......
backfiring.
Had a similar issue and it turned out to be a crack in the flywheel........certainly worth trying another flywheel
-
10 inch Terror
- registered user
- Posts: 1447
- Joined: Tue Jun 29, 2010 9:17 pm
- Xbox live gamer tag: No.
- Playstation gamer tag: PLEASE!
- Main scooter: Lambretta LI Imola 185
- Location: Farnborough Hampshire
- Contact:
Sorted! After eliminating everything electrical, I looked at fuel as the cause. I changed the tap, fuel pipe and swapped the cheapo Koso 34mm for a correctly jetted 34mm Dellorto and it's all good. I followed my son in my van and it was pulling away from me at 80mph. He's as happy as Larry now, and so am I. Thanks all.