01 WR with 03 yz decomp cam valve check procedure?


4 replies to this topic
  • blone

Posted April 14, 2012 - 12:15 PM

#1

Hey guys, I have an 01 Wr426 with the 03 yz auto decomp camshaft that the PO installed (I am unsure if it has the YZ cam degree timing as well, but it probably does). I am curious to know what the valve check procedure is with these mods? When I line up the " I " on the flywheel with the marks on the cover, the dots on the timing gears do not line up, so I am thinking this has to do with the conversion, or the possible YZ timing, or both.

Is there a different procedure for the valves on 03 cam equipped bikes? Or if the bike has the YZ degree timing? Thanks.

  • MANIAC998

Posted April 15, 2012 - 03:38 PM

#2

Those timing marks are not always perfectly lined up from the factory. Are they at least close? With them close to parallel with the head surface, you should have another timing dot on each cam near the very top on each cam. From each one of these dots, I count how many cam chain "pins" are between each dot. Going off of memory (sometimes very suspect!) I believe you should have something like 13 pins between these two dots. Let us know what you've got. Maniac

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

Posted April 16, 2012 - 10:23 AM

#3

The valve clearance checking and correction process is the same as if it were stock. However, if it is an OEM Yamaha 450 camshaft that was used, you cannot time it by the standard methods because the timing marks were stamped for use with a different head and will not put the cam in the right position if used on a 426.

The aftermarket does make Auto Decompression cams for the 400/426 that do line up correctly, having been actually made for the application. Be sure it's not one of those. Contact the OP for verification that he used an OEM cam, and/or look the cam over for markings indicating it came Hot Cams or someone else. If there are no id markings on the cam itself it's probably a Yamaha part. In that case, follow the procedures outlined in these two posts:

http://www.thumperta...078#post3706078

http://www.thumperta...040#post5378040

  • blone

Posted April 19, 2012 - 09:23 PM

#4

Those timing marks are not always perfectly lined up from the factory. Are they at least close? With them close to parallel with the head surface, you should have another timing dot on each cam near the very top on each cam. From each one of these dots, I count how many cam chain "pins" are between each dot. Going off of memory (sometimes very suspect!) I believe you should have something like 13 pins between these two dots. Let us know what you've got. Maniac


13 pins between the dots is what I have.

  • MANIAC998

Posted April 20, 2012 - 03:24 AM

#5

13 pins, Good! Then your running the YZ timing too! How's it run? Any issues at all? Or are you just doing some pre-season maintenance? Maniac




 
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.