Setting Valve Clearance Question


31 replies to this topic
  • TheHarp

Posted February 02, 2010 - 08:10 AM

#1

I've re-installed the head on my yz450. I now need to set the valve clearances. Should I start the process with no shims at all?

  • KJ790

Posted February 02, 2010 - 08:18 AM

#2

I've re-installed the head on my yz450. I now need to set the valve clearances. Should I start the process with no shims at all?


No, the shims sit down in the valve retainer. If you leave them out then the bucket will sit on the retainer itself, and you will not get an accurate measurement of how thick the shim will need to be (since the shim would have to be thicker than the distance you would measure). Stick in any shims you want (as long as they are not too large and yield zero clearance) and measure the clearance, then figure out what shim you need.

  • TheHarp

Posted February 02, 2010 - 08:27 AM

#3

Thanks...I had a feeling there should be at least one shim in there to get started. I'll need to pull things back apart and re-start the process.

  • grayracer513

Posted February 02, 2010 - 11:16 AM

#4

If you are reasonably attentive, what you can do to speed the process up a bit is to take your initial measurements without bolting the cams in place. If you simply seat the cams in their saddles and hold them down while you take a preliminary measurement. This will not be definitively accurate (although if you're careful, you'll be surprised how accurate it is), but it will get you in the ball park much more quickly than you otherwise would be.

  • TheHarp

Posted February 02, 2010 - 11:52 AM

#5

I am reasonably attentive, but not reasonably confident in this process. If it takes me a while, I'm OK with that.

  • tech24

Posted February 02, 2010 - 12:12 PM

#6

for future reference it would've been easier with the head still off

  • grayracer513

Posted February 02, 2010 - 12:14 PM

#7

for future reference it would've been easier with the head still off

Yes, it certainly would, but bear in mind that it is always wise to recheck the clearance after torquing the head down. It can change.

  • tech24

Posted February 02, 2010 - 12:24 PM

#8

yeah thats a good point I wan't thinking of that, glad you mentioned it cause I just got mine shimmed up and probably wouldn't have rechecked it.

  • TheHarp

Posted February 02, 2010 - 04:34 PM

#9

Why would it have been easier with the head off? The engine is still on the bench.

  • KJ790

Posted February 02, 2010 - 05:27 PM

#10

Why would it have been easier with the head off? The engine is still on the bench.


The engine on the bench is the same as having the head off. I think he assumed the engine was in the bike.

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  • TheHarp

Posted February 02, 2010 - 05:29 PM

#11

The engine on the bench is the same as having the head off. I think he assumed the engine was in the bike.


Good...just wanted to make sure I wasn't missing something ELSE obvious.

  • tech24

Posted February 03, 2010 - 04:55 AM

#12

Yeah I assumed it was on the bike, sorry. Just came to mind cause I just did mine since it was off the bike.

  • TheHarp

Posted February 03, 2010 - 03:37 PM

#13

Well, I gave up and took it to a friend/mechanic to do it. It took a lot of shim shuffling to get to a baseline...once they were in the ballpark, it was was relatively quick to get the right shims in place. Glad that's done.

  • usp4u

Posted February 04, 2010 - 04:41 AM

#14

the first time i ever did a valve adjustment while making up an equation to determine what shim I needed I said, "Holy crap, I AM using algebra after high school!".

  • grayracer513

Posted February 04, 2010 - 07:34 AM

#15

the first time i ever did a valve adjustment while making up an equation to determine what shim I needed I said, "Holy crap, I AM using algebra after high school!".

Come on, algebra? More like subtracting decimals after 4th grade :ride:

  • usp4u

Posted February 04, 2010 - 08:58 AM

#16

I dont know, I aways just pull the shim off the valve, mic it, then create an equation of where I am and where I want to so that I dont have try 2 or 3 times to get the clearence I want. Works for me. :ride:

  • TheHarp

Posted February 04, 2010 - 10:05 AM

#17

new shim size = current clearance + current shim - desired clearance

  • tech24

Posted February 04, 2010 - 10:23 AM

#18

oh great now I need a damn calculator

  • grayracer513

Posted February 04, 2010 - 10:30 AM

#19

oh great now I need a damn calculator


Posted Image

  • jayh300

Posted February 04, 2010 - 10:41 AM

#20

Posted Image


they make a newer version of that gray...
(i know because i have to use it on my daughters 6th grade math...)
sorry.... bored.... second snow storm in a week here.....





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