The engine was reworked by a engineer(i have not had engine apart but have known this guy for years he had his first mont of me 15 years ago and has raced this bike with the modified engine and showed me the parts he took out)case's were split and machined(now requires no middle gasket to seal)new parts made and fitted to do away with shims,next time i see him i will ask for more in depth details.this bike has also got needle roller bearings in swingarm instead of bronze bushes.He's not dumb or lucky just a very clever guy.