valves on a 2001 YZ426


5 replies to this topic
  • GONE1445

Posted December 10, 2006 - 08:57 PM

#1

ok just checked my valves last night the motor was cold(dont know if that matters)

had it at TDC as far as I could tell the mark on the fly wheel lined up and the cam lobes pointed away from each other

the cam chain was tight and looked brand new

ok the valve spec's go as follows (left and right are as if your sitting on the bike)

exhaust: left-0.203mm right-0.229

intake: left-0.102mm middle right-0.102-0.127
^^
(couldn't get the feeler guage into the tight spot)

I used a stright feeler guage to check these because the ones with the bend didn't go that small(again dont know if that matters)

are these good and in spec?

or do I need to go buy some bent feeler guages and do it again

  • 642MX

Posted December 11, 2006 - 06:33 AM

#2

Consult a manual....


If you can't help. Don't post. :thumbsup:

  • 642MX

Posted December 11, 2006 - 06:40 AM

#3

ok just checked my valves last night the motor was cold(dont know if that matters)

had it at TDC as far as I could tell the mark on the fly wheel lined up and the cam lobes pointed away from each other

the cam chain was tight and looked brand new

ok the valve spec's go as follows (left and right are as if your sitting on the bike)

exhaust: left-0.203mm right-0.229

intake: left-0.102mm middle right-0.102-0.127
^^
(couldn't get the feeler guage into the tight spot)

I used a stright feeler guage to check these because the ones with the bend didn't go that small(again dont know if that matters)

are these good and in spec?

or do I need to go buy some bent feeler guages and do it again


426 valve specs are: Exhaust .20-.25mm, Intake .10-.15mm. And yes, they should be checked cold. So the all the valves you checked are in spec. :thumbsup: But, you need to check your center intake too.

In order to check the center intake valve I used a pair of snips and made my feeler guage narrower. And do yourself a favor and replace your cam chain. Just because it looks good, doesn't mean that its not slightly stretched and its not eating your crank gear.

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  • GONE1445

Posted December 11, 2006 - 09:38 AM

#4

will do

yea I couldn't cut the feeler guage because it was my grandpa's dont think he would like that

I dont think I am gonna get to ride any time soon so the cam chain will get replaced this winter some time


how do you get it around the crank gear??

  • 642MX

Posted December 11, 2006 - 09:49 AM

#5

will do

yea I couldn't cut the feeler guage because it was my grandpa's dont think he would like that

I dont think I am gonna get to ride any time soon so the cam chain will get replaced this winter some time


how do you get it around the crank gear??


You have to remove the shifter, mag cover, flywheel, stator plate, and cam chain slider bolt. Then you can install the new chain. It sounds like a lot of work, but it can be done easily in an hour. You will need access to a flywheel puller too.

  • grayracer513

Posted December 11, 2006 - 11:59 AM

#6

It should not be necessary to narrow a standard feeler gauge in order to check the center intake on a 426. I've never had to do so, nor use a bent feeler, either, for that matter. One thing that does help is to remove the feeler gauge blade from the stack so that it's lighter and more easily fit into things. Also improves the feel, which is what feeler gauges are about.

On the cam chain, the only thing I can say is that you may well not have to remove the shifter if you can get the cover clear of it by holding it down.

Here's more detail on the cam chain job.





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