I had 90 or so KX80 that had a 100 kit, I currently have a 02 KX100, both big wheels. Ive had the cyl base machined to lower port timing for more low-mid range on the 02 that we will keep. Both run real well. DO NOT TAKE THE PV "system" apart....from what I have read timing is a real pain and it is easily broken when reassembled and operated. Unless of course you read up on it and figure it out.