clutch problem?

[winder]

a friend just bought a nice '99 'Hawk. Looks well maintained. has a few nice mods.
it also has a weird clutch problem: when you try to launch it quickly, the clutch grabs abruptly and let's go. the first time it did it, i pulled the clutch back in and it stopped fine. next time, i tried to get it to launch quick and it bucked pretty bad.
if you take off at a more gentle (normal street pace), and it's fine. bring up revs over 4000RPM and it behaves badly. no noise, just bucking.
the previous owner said it had a "gravity clutch" with some weights that make it do that(?)
otherwise, once going it rides and shifts fine.

i just took it to a track day, and it had no other problems. it even downshifts smoothly. (had more fun on it than i thought i would.)

any ideas?
thanks,
winderOUT

[Rcfive1]

Hey their all superhawks have this problem to some extent dont worry its normal You have the revs up at a light you dump the clutch and the bike says f--k you and almost sends you flying know one really knows what causes it. In a motorcycle compairo between the tl1000 and the 1997 superhawk they brought up this very problem when they took the hawk to the strip exact words by the rider "drag strip launches were hinderd by an oddly chatterd clutch that bounced in and out when the rear wheel spun." I would go for some stiffer clutch springs and diffrent plates I believe barnett makes a clutch kit this may help but not eliminate all together if you want to lunch it hard you need to get over the tank and do not very the throttle opening keep on the throttle(the more the better) and smoothly but briskly keep releaseing the clutch the bike will make a couple of very quick hicups and then go like absolute hell!!!