I have a 99 F4, 07 1Krr and an 05 636. I swapped some cash and a 450 dirt bike for an 05zx10 track bike. I rode the 10 for a few trackdays and was running high 1:20's on it, one day I got on a buddies 636 and was running 3 or 4 seconds a lap quicker. needless to say I promptly traded him bikes and now I'm doing 21's on it. It's just so much easier to go fast on the smaller bikes, unless your an AMA pro. My only advice for a liter bike is practice throttle control. If your hamfisted it WILL throw you. Hold on with your legs not so much your hands, your hands are for steering and using the controls.IMO