whats the best or easyest overbore for the 2002 kx85 i was wondering if a kx100 cylinder will fit on easy? if so what jetting to use or just use kx100 carb? i seen a bunch of companies that have kits but they cost as mutch as a kx 100 motor on ebay. the girl that races this bike is not big enough for a bigger bike yet. but she needs more power NOW as she is racing against other girls on full size bikes.any help or ideas would be greatly apreciated

If I'm not mistaken I think a kx 100 has the same frame. Just like a big wheel kit and a bigger cc engine. As far as the engine heads interchanging I can find in about a week and I will post you back.

thanks id apreciate that we just got a pro circuit exaust system but she needs a lot more i already know the 85 and 100 frame is the same thats why the 100 motor is an option i also found a company that uses the 85 cyl on the 100 motor to make a 99 cc but they dont say if theres any machining and they get like 850.00 and thats what i see 100 motors going for on ebay

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These guys do nice 99cc overbore kits for about $800, a 105cc bore and stroke for $1800: http://www.maxpower-engines.com/big-bore-kits/kx99.htm

Or you can put in a 2mm stroker crank from Hot Rods for about $200 during a normal overhaul.