Valve Clearance

I've been watching and posting for 3 weeks and havn't see anyone discuss intake and exhaust valve clearance checking or adjustment. I know the WR426 utilizes "shim in a bucket" technology that I have no experience with. I now have 260 miles on the machine and it needs to be checked. I am mechanical and not affraid to tackle that project if I had a little more tech advice and experiences from others to draw on. The manual discusses the subject but it's rather vague. Are there any good links that adresses this subjects more thoroughly? I'll hang up and listen !!

F6, if you have the repair manual you should be OK. I did mine last week. Once you remove the top end cover it will make sence. A couple of pointers, wrap the cross bar with something (glad wrap) so dirt won't fall into the top end. The motor must be at top dead center, and on a 4 stroke this happens every other turn of the crank. The cam gears have 3 punch marks and these line up at 9-12 and 3 oclock when at TDC. At TDC the cam lobes point outward ( exhaust forward and intake to the rear of bike) The feeler gauge fits under the cam. To check clearance is less than an hour even the first time, to change schimms gets more involved but not bad. Good luck

once you have the manual in hand, your feeler gauges out a CLEAN bike and clean floor to put it on, its very, very easy to do. write down the gaps as you go and then off to your yamaha dealer for the correct size shims. did mine last week and the 2 of the inlets we're at .13mm and one was at .15 both the exhausts were at .25mm rang my yamaha delaer for advise he said wait to till next oil change and check em again of their under .13 then we'll do it.



There's a good article in febs issue of Dirt Bike on how to do it.

Thanks to all for the advise.

I put 2,800 miles on my bike with no valve adjustment. The bike rips. These bikes are highly reliable and requires minimal valve adjustment. You will know when it is time to adjust, your bike will not have any compression. You will kick it over and will not need your compression release. Until that point ride it.

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