More help needed please

2 replies to this topic
  • IHScoutII

Posted February 12, 2006 - 03:28 PM


I just checked the valves on the 426, and it came out to-

Exhaust on both left and right- .356mm

Intake on all three valves- .178mm

Now since the shims from Yamaha come in .05 increments, is it safe to say I should go one size bigger on the intake and two on the exhaust?

When i went to measure the clearances, the feeler gages I used to come to the measurement above, was hard to get in at first because it was trying to go in at an angle, but once the gage was in, it was how I would put it, not lose but had a little bit of pressure on them. Does this sound like I am measuring them correctly?

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  • grayracer513

Posted February 12, 2006 - 05:55 PM


Feeler gauges should glide smoothly, but be in contact with both parts. The resistance to pulling them through should be like what you would get from laying the end of a 17mm open end on its edge on the gauge on a metal sheet and pulling the gauge out from under.

Going one size bigger on the intakes is indicated, yes. That would put them at .13mm (rounding). And yes, I would go two on the exhaust, but check your readings. It's not very common for clearance to increase of the 426, rather than decrease.

BTW, is yours an '00, or an '01/'02?

  • IHScoutII

Posted February 12, 2006 - 06:17 PM


It is a 2000, I just picked it up the other day and I wanted to check everything over. It has the '03 cam in it if it makes any difference.

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