Mine is a 2000 kmx 125 model, last month i blew the piston ring while racing. I now have a 140cc. My friends here in our place fitted it with a bigger sleeve, a 140cc piston, rings, from kawasaki brutus that can be rebore (according to them) up to 200 cc and it feels like a new bike, quick and economical because you dont force the engine too much to produce more power. before they told me that kmx blocks are disposable, now it is the thing of the past.