Shim changes after Valve Job -


3 replies to this topic
  • yamaha491

Posted April 25, 2008 - 03:02 AM

#1

I have an 06 YZ450F with 90 hrs of use and I decided to do a valve job. I sent my head off to have the valves seats machined and and new OEM valve components installed. I replaced all the shims to achieve the correct valve clearance and I ended up having to make a bigger adjustment on the intake side than what I would of expected. The stock intake shims were all 192's and I ended up with two 160's and one 165 (.0106in to .0125in from stock). Does this seem to excessive? Is there a service limit and if so how do I check with all the variables?

  • William1

Posted April 25, 2008 - 03:33 AM

#2

Not at all uncommon. When valves are replaced, the seats are cut, theoretically, enough to provide a good seat. This machining 'tightens' the valve. sometimes, the valve stem will be shortened slightly to make the overall clearance in range. As long as it can be shimmed into proper clearance, you are fine.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Ronin 26

Posted April 25, 2008 - 10:27 AM

#3

When i re-cut seats it's usually one shim size thinner, after a perfect seat.

Sounds like guy cut allot. Not a big deal, just lowers compression, reduces spring seat pressure. If they are cut MUCH deeper I'd be shimming the vavle shim to get seat pressure back.

1.90mm - 1.60mm = .3mm or .012 inches deeper. Not huge but a wee bit excessive. Seat pressure will still be fine.

  • grayracer513

Posted April 25, 2008 - 11:06 AM

#4

If they are cut MUCH deeper I'd be shimming the vavle shim to get seat pressure back.

You meant "shimming the valve spring" did you not?





Related Content

Forums
Photo

2016 YZ450 by CaptainKnobby


Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies
Reviews

Yamaha YZ450F 2017 by Chris.GVS


Yamaha YZ450F 2017
  • - - - - -
  • 0 reviews
Wiki
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info


Articles
  • 0 replies
Forums
Photo

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F


Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies
Forums
Photo

Megabomb Fitment by 288yz450


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.