I may have a BIG problem please advise!

Hey guys I have a 99 wr400 and I am doing a valve adjustment for the first time. (i've owned it since new) so I know its never been done. Anyways I check everything, the exhaust is within specs, but the intake is way tight. It is .076 (I think, my notes are outside) anyways the spacers that are in there are 180. Rounded up and down, so that comes out to me needing a 240 spacer. Thats the biggest one there is. Does that mean I can't ever do an adjustment again without getting a new head?!?! Please let me know if anyone has any sugestions. I may just have to sell this and get a 450! LOL the wife will love that. Thanks.


6yo WR that's NEVER had the valves checked!!! That's about 5 and a half years overdue..... :) Sounds like you are up for a valve job at least, dunno about a new head. It depends on how worn everything is. Get a good machine shop to check everything out for you. Actually at 6 years, and no engine work at all, get the whole engine checked out. The 450 might work out cheaper.....

Hmmm. :) How did you measure the clearance being 0.076. Thats a very accurate measurment for a feeler guage. Most guage sets go in 0.03mm incriments.

If the clearance is tight , you need a thinner pad.

If the clearance is loose, you need a thicker pad.

For arguments sake, lets say you have 0.07mm clearance on the inlet 1 and you have a 180 pad in there. To get the clearance up to spec you would install a 175 pad. That would give you 0.12mm clearance. I assume the 400 has the same specs (In 0.1-0.15mm Ex 0.20-0.25mm)) as the 426.

You dont have to worry about buying a new head, or even valves for that matter. The WR400 has steel valve. This means all you have to do is get someone to grind the valves and seats, and then 'tip' the valves so you are back in the middle of the shim range.

Hope this helps

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