my 400 only slips when over 10 mph now first is this I can sit on dry pavement and she will spin the tires no problem but once I hit 10 she will start slipping and when it grabs it doesnt make a shutter it makes a loud bang I cant smell a belt burning put a new one on anyway (didnt help) I cleaned the clutches ( my primary has rollers in it and my secondary has 1 main spring pretty much the same as the Yamaha) it doesnt slip in reverse though no matter how hard I come on to her I lifted it up and spun the back wheels by hand and you can hear the cogs inside (sounds like something is lose) any ideas