I recently purchased a 1999 Big Bear with allegedly low hours. What I notice is that the valves sometimes get noisy when the unit has been running for some time. The noise is not consistent especially when the motor is cold. Since the previous owner never serviced the ATV I was wondering if a valve adjustment was in order. Is this model known to have a noisy motor, it seems to run fine with no loss of power.

 

Yep, they are known to be mechanically noisy but very reliable. My valves were recently adjusted and the mechanical noise is still there so this is normal. Mine is quiet on start up but gets a little noisy once it warms up, a Big Bear trait I guess.