Hey Rich, I stripped my top end last night and found everyting 100% Ok in the piston department. Piston & rings were in 'new' tolerances...these motors are amazing. Carb slide intact as well. The only thing I did find which was 'wrong' was a frayed throttle cable which was hidden until I actually removed the carb. Dont want to teach granny to suck eggs but I guess you have checked that ? I did find something weird though: The top of the piston was covered in sticky black stuff: burnt oil I guess, but i could remove by wiping & contact cleaner and it came away real clean. Also the three intake valves are charcoal black whereas the the two exhaust valves are a nice grey metallic colour. I know previosuly I was running rich because I was an air filter monster...I hadn't cleaned the filter in months after riding in some pretty dusty conditions (2 x 3 hr races where I had to wear a wet bandana to avoid suffocating on the dust cloauds and visibility 0 at some points of the race.) But whats with the difference in colour intake vs exhaust ?? Having fitted a new pipe recently and my first run in months I could smell burning oil whenever I stopped, but ZERO smoke out of the exhaust. When I cracked the head cover found pooled oil on top of the front right valve bucket. Smelt of burnt oil too when I opened her. Could I have overfilled the oil ? I remember checking, and it was 'high' on the mark but didn't seem overfilled. A long list of questions but if you can help...that would be great.