adjusting vavles w/ out shims for starting point!?!?!?

6 replies to this topic
  • Guest_BrandonV_*

Posted May 23, 2005 - 07:43 AM


Sorry about the subject as it doesn't probably make sense, but I dont know what else to put there.
I got my head back from the shop minus the shims under the buckets :)
I have no idea what sizes they were and no idea for a starting point to begin.

Are the exhaust and intake shims interchangable or specific to each side?
What size(s) would be a good starting point? I do not believe there was a 'standard' from the factory since each part varies, correct?

Bike is a 2000 426 and I will be putting the 450 exh cam in.


  • Dano426

Posted May 23, 2005 - 08:10 AM


Here is what I am running with my 01 YZ 426

exhaust (03 450 cam)
From the shift side 190 & 195

190 -- 200 -- 195

If you don't have alot of shims, hot cams sells a "refill" kit for there shim kits
You get one each of a 180 - 205 for $34.00 That should get you started

  • Guest_BrandonV_*

Posted May 23, 2005 - 08:28 AM



thank you much.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted May 23, 2005 - 08:43 AM


Here's what you can do:

It will be easier if you have a reasonable collection of shims to work with, but if you don't, take one in the area of 170-175 and set it on a valve. (sidebar: keep the lifters in the same bore they are in now. Each of them may be very slightly different thicknesses through the top of them)

Set the cam in place and tap the ball bearing down into its saddle with a plastic or soft faced mallet. While holding the cam down with your fingers, check the clearance. If zero or less, go to a smaller shim size and check again.

This will give you a ballpark idea of what size to use. If you are careful enough, you can select the exact size 3 out of 5 times, but ALWAYS double check with the head torqued down and the cams torqued in place.

  • Guest_BrandonV_*

Posted May 23, 2005 - 08:49 AM


And thank you too!! That'll certainly be easier than torqueing the caps everytime like I was going to do.

I was about to order the Hot Cams refill shim kit in 1.80 to 2.05mm (5 of each) sizes. I didnt think I'd end up below a 1.80 on either the exh or intake.... I guess I can go to the dealer for any smaller ones if needed.
Grayracer, can you verify the OD on the yamaha shims is 9.48mm?

  • grayracer513

Posted May 23, 2005 - 12:32 PM


I don't know the specific size, but a reliable source here once posted that there are two sizes in use on modern Japanese tappet-over-valve setups; one for the 250F's, and one for the 426/450's. If your Yamaha dealer doesn't have what you need, a Honda dealer might have them for a CRF450. 9.? mm sounds about right. The ones for a 250F are much smaller.

  • Dano426

Posted May 23, 2005 - 12:39 PM


can you verify the OD on the yamaha shims is 9.48mm?

yes the 426 shims OD is 9.48 mm

Related Content


2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

First Hare scramble tips by dhend8

Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  33 replies

yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

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.