aight i have had this problem befor and it was the one way bearing or starter sprag on the flywheel. i replaced the bearing only. that fixed it for a little while. now its doing the same thing. making terrible noises when trying to start it up. so this time i replaced the bearing, hub, and gear, everthing that one way bearing touches. its still making the same grinding, scratching, knocking. noise while starting. as far as i know the motor is fine. ran perfect last time i rode it, just rough to start it.

anybody have any ideas about whats going on with it?

 

These Rotax motors create a lot of compression and when they don't start the "kick back" is pretty loud and seems to spook some folks in to thinking something has broken. It may just be the flywheel spinning back forward. They are a noisy motor but very reliable.
Are you sure it's not just a noise that you're not used to with other makes?

 

well this bike has never done it befor other than now. i can take one plug out and still hear the noise..

 

Sounds like the one way bearing is going bad again.