My ex Team Green bike came with numbers on the cases, but they didn't match the VIN number on the frame. What a blast that was at the DMV!
The Team Green mechanics told me they would send a batch of motors off to a builder, Varner Motorsports in my case, and swap them around in their race/practice bikes. All of the motors had the same clearances, porting, pistons, etc., they just put different exhaust and and some modified carburetors on some of the riders bikess. They said that the motors were slightly modified (mild porting, no radical compression. Heck, mine runs perfect on 91 octane!), but they weren't too far off from stock specs because reliability would diminish in the races such as the Baja 1000. The few Team Green desert KX500s I've either worked on or have seen the internal components, even had stock reeds/cages, which you would think would be an easy way to make more power. In the desert, more power can equal more tire spin and more wear. Go a few hundred miles and there goes any horsepower difference!
On a side note, just a few weeks back they had a District 37 race in which the course traversed part of a dry lake bed. Someone had a radar (check it out here:
http://www.district37ama.org/forums/showthread.php?t=55077) and the fastest pro bike was Kurt Caselli's 450 KTM at 95mph. I can remember when I was a teenager, and I was avidly racing desert when the KX500 ruled everything. Every time there was a radar around (a motorcycle club called the Badgers had a bunch of cops in it and one had a radar gun) all of the pros 500's would do well over 105 mph on the dry lake beds and this was over 20 years ago! Testament to big bore two strokes! I remember my old man telling me to hit my kill button every once in a while when I was racing my KX250 over the dry lake beds just to give the cylinder a coat of oil without the fire. Used to see a lot of seized bikes out there from guys that just wouldn't let off.
