I was wondering if somebody could answer this for me. My buddy has a 2004 yfz450 and we are going to be adjusting the valves this weekend on it. I found the specs for the intake and exhaust clearnce, 0.10-0.15mm and 0.20-0.25mm. My question is why is there a range on the adjustment? I have a 2004 400ex and my specs are intake .10mm and exhaust .12mm. Is it beacasue the 450 is a race breed machine? Should I use a lower or higher measurement depending on how hard the machine gets ridden?



Yes, I own a Honda, but that 450 is something else, it's like yamaha got the plans from aliens or something.