Bought my bike new in 2008 , have done all the regular maintenance like oil and filter changes every 10 hours , air filter cleaned every ride , shims I checked about every 40 hours . Inlets started needing shimming regularly from about 300 hrs and i knew i was riding on borrowed time . Decided to change the inlet valves and at the same time do the piston as the motor had not been opened in 350 hours . Piston has slight wear on the centre of the skirts , barrel still excellent condition with no ridges or scratches , piston pin had a little wear . All parts still in spec as per manual . Left inlet valve was very worn , right inlet was better than ive seen on bikes with less hours . Replaced the inlet valves with OEM valves and replaced piston kit with Wiseco standard compression . 450 was a pleasure to strip as everything is easy to get to , and parts are not small like on the 250's ive worked on .