i have a 2001 yamaha gizzly 600 the flywheel gear and the starter bendix gear have shorn off not sure why it was like this when i got it is this a common problem

 

I would say no. The 595cc motor was used from the mid 1980s to 2004 on the XT600 motorcycle (1990 was the first electric start). Yamaha just threw it in a ATV to get a big bore 4x4 out there quick.
Yamaha XT600E (1990-2004) - Yamaha Motorcycle Reviews
Those motors are very reliable and had the bugs out of them long ago.

 

thanks and the bike likes to "eat" pickup coils and its not just my bike ive helped a few people change them 4 different bikes in all. is this a known problem

 

If they eat up pick up coils on the motorcycles then they should on the ATV. Like I said same motor.