2004 Yamaha YZ 450 F "big bear wont fire" Questions

big end bearings and it will not fire up ...any suggestions ? check for spark. Check for gas. timing must not be dead nuts on TDC it must be retarded a little. Do you have the manuel? i am also having

big bear 400. hard to start wont stay running unless chock is on spits and sputters and ocacionaly back fires. when try to throttle it it boggs through intake. I have an 01, and it started doing this.

...big bear 350 atv. I'm trying to get the electric start working again. i knew the starter clutch was bad so i repaired that. it has a new battery and solinoid. The system wor I have a 1987 yamaha ...