it just removing material lightening it. advantages are less rotational mass putting more power to the wheels and less on spinning the flywheel. disadvantages are less rotational mass as well, the motor wont carry as much inertia making the motor less torquey and have the tendency to stall more
I have it done. I would just by another fourwheeler instead of sticking money into the old girl. If you want to though it's an alright mod. More easy to stall but rev's quicker.
Get you a pipe first this lightened flywheel won't help a hole lot because the motor is stuffed up and is reving about as fast as it can untill you mod it so it can breath better
hmf white bros yosh pipes are good the only one i wouldnt recomend is a cobra most people dont like dg pipes i personaly run a GRT-R its my fave but its more on personal preference