This is one of the engine-builders bikes.....
 

...run by a team...the bike is a Yamaha SZR660, Bought off ebay for �450 as a non-runner, and was turned into a racer. This was not their best weekend tho'.....
http://www.youtube.com/watch?v=ZDEV1ySXszE

Guy with the hat looks like my Ex's dad!

Here is some other info for you.

Weights stated below include piston, rings, clips, and wrist pin.

Stock piston Raptor 700 = 537.2 grams[/font]
JE 12.5:1 102mm = 487.7 grams
JE 12:1 105.5mm = 506.8 grams
JE 12:1 105mm = 506.8 grams
CP 11:1 102mm = 524.9 grams
CP 12:1 105mm = 534.9 grams
Wiseco 11:1 103mm = 535.4 grams
Wisco 14:1 102mm RE = 545 grams

If you can add the XT's standard piston weight to my list.

i think JE's are supposed to be pretty light, but you cant lighten the generator....

You can lighten the flywheel if you want it to rev quicker.

:hiding:its got a generator, with timing marks....how can you lighten that? I can't find a flywheel on a XT, i've looked on the parts catalogue.?

Doner engine found!!
 

A complete unit, picking it up tomorrow.....

I am probably only going to use the top half of it..barrel, head, cam (for re-profiling), throttle body etc. I already have a spare barrel, but now I'll have two!
http://i933.photobucket.com/albums/a...g?t=1283551209

Why don't you modify the motor you just bout & keep you XT660 motor a side, that's what I would do.

I could do..its been down the road, so clutch/rotor covers and possible other crankcase damage. If I can get the crankcases/covers I need...I'll get searching.

Kev, it makes sense to go with your suggestion...

Another thing to look into with regards to throttle bodies...are they ALL 44mm......??? I THOUGHT I had seen 45mm on somewhere...with other manufacturers using the engine, this MAY be correct, but don't quote me!