Valve clearance report

These bikes are amazing. I checked the valve clearance on my 426 when new, and I just checked it again after nine months of

riding MX once or twice a week. The clearances changed no more than .0005". This is my third YZF, and they all stayed within .001" over one year of riding. If I buy another one, I may not bother checking them at all. You high mileage off road guys may have a different experience.

Scott F

Just checked mine on Sunday with about 2700 miles on my bike.

The intakes were right in spec (.15 went in easily but .20 did not go in at all). My exhaust valves may be a little loose as the .25 went in easily and the .30 went in with some minor resistance. However a .35 would not go in at all. I can't measure exactly as my feeler gauge doesn't go smaller than .05.

My engine seems noisier than normal lately, that is why I checked. But they seem to be in spec. So I'm not sure what is wrong if anything at all.


I suppose I'm a bit paranoid because of what happened to my bike but if you are noticing an increase in engine noise you may want to check the clutch side of your motor.

My 426 was making noise and I found, w/ the help of someone on this forum with similar problem (thanks again to whoever that was, you saved my butt):

1) Rivets on back of clutch basket were rubbing cyl. bolt boss inside the case

2) Nut holding Counter Balancer gear was loose, straight key was rounded off, creating lots of play

3) Nut holding main drive gear was loose

And when I say loose I mean VISIBLY loose :)

When I fixed these problems (very minor except for $225 Hinson basket) the extra noise was gone. I probably could have done without the basket (and just ground rivets down a bit) but my clutch does work 100% better now, less chatter and grabbiness (I just invented a new word!)

BTW, I at first thought the noise was valvetrain related but, with bike idleing, I could tell the noise was coming from the right side just by sticking my ear down there. Watch out for the header :D

For '01 there will be no straight key, the CB gear will be held in place by splines. Makes me wonder how many other bikes are out there with keys rocking back and forth and rounding off due to oscillating (push-pull-push) force of CB weight, not to mention loose nuts :D

As for your exhaust valves I would think that a tad loose is better than a tad tight because of the extreme temps they go through.

But what do I know...

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