valve clearence check...

today i did it first time on my bike and the intake valves was right in the middle . the exhaust was on the tight side , i had to push the feeler gauge a little bit with the 0.25 . do u think i need to adjust or its ok till next check?

how often do u check your valve clearence?

I usually check my valves every spring and fall. If you had to muscle the feeler gauge between the cam and the lifter it is too tight. The example that I was thought is the feeler guage should have as much drag as a playing card in the bottom pages of the telephone book. sure it's a hokie analogy, but the moral of it is you shouldn't have to use force. :)

If I was right on the tight side of the spec, I would take the next "convenient" time to tear it apart and order the shims. But don't sweat it.

Tear it apart, figure out what you need, put it back together, order the shims, tear it apart again, etc.

It will seem like a big deal the first time through. After that, it is no problem. Be careful with the bolt that holds the decompression release, I stripped mine, even with a torque wrench.

After doing some faq finding on this and no help from the Local Wrench heads at the Yami chop.

I looked up a very old friend, I was concerned about the same thing. My friend has been buidling thumpers a long time, mainly dirt trackers but he now has two sons riding expert classes and pro in the local area mx tracks on 426 and a 250.

Here is what he told me:

The settings perscribed by the manual for min / max, should be checked in two ways.

1: The manual points to checking with the valve high end lobs away from each other at the TDC (I) Mark. This is the min setting at TDC the valves should be setup for.

2: about 1/8 " further past TDC ther are two divits on the Cam Gears


When Set flat as the pic above shows this is the MAX setting.

If the valve clearance falls with in these two areas ok meaning that the min and max is not exceeded, then you are in limits.

Also not, Instead of buying new shims Motoman and others have used a plate glass, 600 wet sandpaper and basicily ground down the shims to fit properly. Saves money and gives you that more intamate time with your Bike :)


This would be helpful on the WR426 forum on the '2001 WR426 YZ Timing NO!!??' post at here.


hi egoahole, so it means that im realy on the tight side , right? cause i did it like the manual shows and i had to push a little bit the 0.25mm to fit in....

btw a friend told me that if the 0.2mm fits in good i dont have to worry for the next 1000 km.

what do u think?


Personally I would try to loosin it up if you are as tight as you say. Try the methods Motoman and others have used buy wet sanding the shim(s) that are two tight.

Mine were on the tight side but I did not have to force the gauge in any much harder then a good firm push, I concider that fair. Checking them in stage two of my earlier post shows I am well in tolarance, and they slide in easier no effort.


I disagree, If you have ever degree wheeled the valves on older thumpers, the proper setting is to adjust per degree of the cam lob lift.

I think it is valid to see the min max for both yz and wr... :)

Curiuos why you think it is not valid for YZ

[ April 22, 2002: Message edited by: EgoAhole ]

[ April 22, 2002: Message edited by: EgoAhole ]


I think you misunderstood. There is another post that this information would be helpful for. Just that.

I admit I do not understand your post regarding 'proper setting is to adjust per degree of the cam lobe lift', but I'm curious.


I proposed some time ago that we could swap odd shims amongst oursleves and not have to sand shims or order only even numbered shims. Nobody responded. My '00 426 came with 1.78mm shims that fall between 1.75 and 1.80's. For fine tuning the lash, I thought that we could trade amongst ourselves. I was wrong.

Oh Noble Boit :D

I will take that bet and raise it 1.90

I will be interested f I need such shims.....


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