leave the motor alone, you can change the stock air filter and maybe a new cdi box, makes the top end speed a little higher, and maybe new springs for the clutch ( duners kit ) that what they call it..does it make a differance, i really dont think so....and if you want to do suspention, get walker evans shocks or even do a mid travel kit if you want...i run mine stock and it is fine....If you want a lot of info go to www.rhinotalk.net and they have a lot of info on mods and trouble shooting...