installing new cams, shimming questions

5 replies to this topic
  • Rcme86

Posted April 16, 2008 - 06:41 PM


Okay, i have two new hot cams and im kinda lost on how to start. what size shim should i start with? and can i shim them with the cyl. head off the bike? thanks.

  • thumpyz

Posted April 16, 2008 - 07:07 PM


You could install them with the cylinder head off the bike, but that would make your timing chain impossible install, if its a timing chain worth using.

  • thumpyz

Posted April 16, 2008 - 07:12 PM


use your old shims to get a base measurement. Make sure to use a torque wrench when you tighten your cam caps, you will smoke check the cam, cap and the journals in the head if you dont. Trust me, you dont ant to do that. Your manual should run you thru installig a new cam. good luck.

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

Posted April 16, 2008 - 09:52 PM


Why would the head be off?

The clearance can be checked and adjusted with the head off but the cams have to be removed to access the head bolts and to install the timing chain. If you do set the clearance on the bench, be sure to recheck it once the head is torqued down correctly.

  • Birdy426

Posted April 16, 2008 - 11:25 PM


Sart with the shims you've got. If you've got a 426 and they were for your stock cam, you will have some pretty good gap-osis, as the HotCams cams have a slightly smaller base circle than the stock Yamaha parts. If that doesn't work, start with no shims and measure what you've got. It can get kinda pricey buying shims for trial and error, though, so maybe talk to the mechanic at your local shop and see if he'll do some shim swappin' for you.

  • Rcme86

Posted April 17, 2008 - 05:55 AM


well the head is off because i was gettting some new valves put in it. I guess ill just try it with the shims that are in it from the stock cams and see where im at. thanks for the input.

Related Content


Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  35 replies

YZ450F 03 Sparks driving me crazy by SirAttard

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

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 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.