Valve Adjustment - Yes or No


11 replies to this topic
  • jcbikes

Posted April 13, 2010 - 10:52 AM

#1

I have a 02WR426 that I purchased used 7 months ago. The bike runs perfect. Usally starts 1st kick cold or hot. Anyhow, today I decided to check the valves to see if they were in spec or not. Here is what I found.
The exhaust valves were both at exactly .203mm. (spec is .20 to .25mm)
The left intake valve was at .10mm which is in spec from .10 to .15mm.
My question is on the center and right valves that were both at .08mm which is off by .02mm. Should I make the adjustment for this small amount (a little tight) or not worry about it and just keep an eye on it? Would like some expertise on this please.
Thanks, JC

  • 123BigcoopDawg576

Posted April 13, 2010 - 10:56 AM

#2

Here is what I found:

The exhaust valves were both at exactly .203mm. (spec is .20 to .25mm)
The left intake valve was at .10mm which is in spec from .10 to .15mm.
My question is on the center and right valves that were both at .08mm which is off by .02mm. Should I make the adjustment for this small amount (a little tight) or not worry about it and just keep an eye on it?


Anything that was in spec (both exhausts and the left intake) I would leave alone.

The other two intakes which are out of spec, I would adjust...

Once you've made the adjustments, check again after a few hours or so :thumbsup:

  • OUTERLIMITS

Posted April 13, 2010 - 11:07 AM

#3

Anything that was in spec (both exhausts and the left intake) I would leave alone.

The other two intakes which are out of spec, I would adjust...


Agree with Coop except I would adjust them all to the middle or looser end of the range as long as you have it all opened up. You into it anyway at that point and the cost of shims is almost nothing. Just think, this will probably be the first valve adjustment that bike has seen. Not bad for an 8 year old sled with titanium valves on both sides! :thumbsup:

  • 123BigcoopDawg576

Posted April 13, 2010 - 11:11 AM

#4

Not bad for an 8 year old sled with titanium valves on both sides! :thumbsup:


Brett...its not a Honda :lol:

  • jcbikes

Posted April 13, 2010 - 11:20 AM

#5

Thanks guys. Yeah, I think this is the first time the valve cover was off. Do valves have a tendancy to get tight or loose? I read somewhere that the exhaust valves were of more concern being tight. JC

  • mjslim

Posted April 13, 2010 - 11:26 AM

#6

You could just keep your eye on it a while, but just don't wait until the bike becomes hard to start - at that point one of your valves will be leaking. When you decide to do them, I would shim the intakes but also the exhausts, even if the exhausts are still at .203mm. Put them at the high side of spec, that way you won't have to worry about them for a while. May as well do them all while your in there, rather than have to come back later to do the exhausts.

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  • OUTERLIMITS

Posted April 13, 2010 - 11:34 AM

#7

Thanks guys. Yeah, I think this is the first time the valve cover was off. Do valves have a tendancy to get tight or loose? I read somewhere that the exhaust valves were of more concern being tight. JC


The tendency is that they become tighter with wear

  • mauricedorris

Posted April 13, 2010 - 11:37 AM

#8

You already have the valve cover off. So just do it. This will be a rare thing to do.

Do not wait until you are out on a trail somewhere in the middle of the heat, with a hot engine that won't start because the valves need adjusting.

  • grayracer513

Posted April 13, 2010 - 04:13 PM

#9

Yamaha builds their engines to as near the minimum of valve clearance as possible at the factory. There is no reason to adjust any valve that meets the minimum specification in any way. The two intakes at .08 should be adjusted, then revisited in 5-10 hours to ensure they aren't receding. The likelihood is that this is simply the original bed-in of those two valves that was never corrected, but if you've checked them before and found them at .10 or more, it could be a concern.

  • jcbikes

Posted April 13, 2010 - 05:35 PM

#10

Gray racer,
This is the first time i checked the valves since i purchased the bike used. As far as I know, the previous owner did not have them adjusted. Now you have me wondering if this could just be how they came from the factory all on the tight side as you say.
.02mm off is not much and the bike is running fantastic.
thanks for your thoughts. I put the bike back together without changing them for now.

  • grayracer513

Posted April 13, 2010 - 06:04 PM

#11

At the risk of redundancy, you should adjust the two that are below spec.

  • jcbikes

Posted April 13, 2010 - 08:01 PM

#12

I needed the bike together for a ride with friends, that is why I put it back together today. I will adjust the two intakes in the near future. thanks for your help!
JC




 
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