I'm installing a new piston on my 14 YZ450F since its at about 110 hours. Just preventative maintenance.
So I checked the valves for the first time while I was in there. The exhausts were perfect at .23mm, spec is .20mm to .25mm.
The intakes were right at .13mm, maybe just a little looser. My .15mm gauge would not fit at all.
Spec is .13mm to .20mm, so they were just at the tight limit.
Both had 200 shims installed. Next step is 195, which should make the clearance around .18mm to .19mm.
So it will still be in spec but at the loose end.
Should I leave them as is or shim them to the loose end?
Since this was my first time checking them I have no idea if they have moved, or if they were set on the
tight side from the factory. The bike still starts the same as new and I feel no power drop off.
Edited by luckyguy19, December 03, 2015 - 09:34 AM.