Valves - loose side of tight, or tight side of loose?

2 replies to this topic
  • knowlimits

Posted November 12, 2005 - 12:22 PM


Checked the valves on my 05 WR450 today and the intakes were bang on .10 but the exhaust valves were tight. Before I get the shims should I go a little looser (.25) or tighter (.20)? One was .15, the other .19 and they should be .20 to .25 mm. I know they tend to tighten up over time and figure looser is better since there is less risk of burning than if they were tight. I'm sure there is a little power loss from running them on the looser end but it's got a crapload of power anyway.

Any harm in bringing them to .25 and .24?


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  • Gadsen

Posted November 12, 2005 - 12:49 PM


You can only fine tune so much with shims. And now that they are settled in (valve faces mated to seats) the changing will slow way down, and remain more constant. But when they do wear normally, either valve face/seat wearing down, or stems stretching, they will get "tighter" (less clearance) so if it was me, shoot for anywhere in spec, and if you have enough shims to fine tune, go for the max clearance without exceeding specs. Just my opinion. Stay away from too close to minumum unless you want that "extra lift/duration" and dont mid going in more frequently. :applause:

  • knowlimits

Posted November 14, 2005 - 03:23 AM


Thanks for the advice. I'll shim them to the looser tolerance and forget about it for another year. Looser = good.


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