my 98 zx9r is having issues when i go to dump the clutch for a wheelie around 9 or 10 grand rpm. The moment the clutch fully engages and the wheel starts to come up, i hear a nasty clunk/slap inside the engine somewhere and a drop in power and the wheel comes back down. At first i thought it was backfiring (somewhat similar sound) but it definatly is not. The sound comes from the engine and does it every time i dump the clutch at that rpm. It shifts fine through all the gears when i tach it up through all the gears. I can ride it hard in each gear with no transmission issues. I can even chain lash it in each gear and none of the gears slip or anything. I installed a brand new clutch with all new kevlar plates and steel plates and springs. The only time i hear this problem is when i dump the clutch for a wheelie. Any ideas?