Valve Adjustments?

5 replies to this topic
  • pedman

Posted November 03, 2003 - 09:47 AM


Anyone done valve adjustments on WR426F? After reading the manual, I am not sure if I really want to do this if there is no problem.

This should be quick and easy right?

Thoughts and Comments greatly appreciated.

  • LJ

Posted November 03, 2003 - 11:08 AM


Easy, just did it this past weekend.

Follow the manual and you won't have any problems.

A couple of tips:
1) Stuff a rag in the area where the timing chain is so you don't drop the valve shims or cam retaining rings in there. It would ruin your day.
2) You need a torque wrench to torque down the cam caps. I was able to use a 3/8 drive with a 3/8 to 1/4 drive reducer and use a wobbly extension to get to the screws in the middle of the cam cap on the intake valve. It looks like it won't fit, but it will if you are patient.
3) Mark the cam chain with a black marker next to the index marks on the cam gears. It will insure you put it together correctly.
4) I didn't have much luck getting all of the shims I needed at the yamaha dealer. Get a piece of 180 grit sandpaper and a piece of glass (or anything flat and hard) and lap the shims down yourself (use water!). I found it didn't take too much work to lap the shims down .050mm. Use a pair of calipers to measure how much material you remove. Clean up the shims with a piece of 600 grit.
5) Watch out for the retaining clips on the cam. I didn't see them at first, and I'm lucky I didn't drop them into the motor. Just be carefull and use rags to cover openings in the motor and you'll be fine.
6) When putting the cam caps back on, wiggle the cams back and forth in the head to align the cam cap dowel pins and the cam retaining ring. If you do that, the cam caps will drop right in.

Good Luck!

  • pedman

Posted November 04, 2003 - 08:35 AM


Looks like more time than my XR400. I do appreciate the information :)

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  • GrahamO

Posted November 04, 2003 - 02:40 PM


Does your XR400 have rocker arms? Makes adjusting easy...

My dad and I were checking our valve clearances this weekend. He rides an XR250. In the same amount of time I took to check mine, his were checked and adjusted.

  • pedman

Posted November 05, 2003 - 06:31 PM


It did before I sold it and got my WR. I thought it may be good to check the valves, but I am second guessing this procedure. Not confident in my skills :)

  • Scott_321

Posted November 06, 2003 - 03:42 PM


Just checking them is actually pretty easy. LJ explained how to adjust them if they are out of spec.


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