HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
brewerjw1011

02 yz426f timing marks

3 posts in this topic

Hey guys i pulled my valve cover off today to see if my valves were in spec and i got it to TDC and the timing marks werent parallel to the block i lined the mark on the crank with the l mark on the flywheel and then the cam marks were off. I thought the cam marks were susposed to be parallel with the block at the same time while on TDC do yall have any ideas this is my first time adjusting DOHC engines and im puzzled any help from u guys would be greatly appreciated i kno my valve spec for the intake side is .10-.15 and exhaust is .20-.25 correct me if im wrong and when i stuck my feeler guages in there it was way off on intake and exhaust so yea im kinda confused any help from yall would be greatly appreciated thanks

Share this post


Link to post
Share on other sites

First, there are 3 marks on the flywheel.  They are clustered together, and the first two from left to right are normally connected by a horizontal that makes them resemble an "H".   These are fro ignition timing.  The third mark is TDC for the cams. 

 

If your 426 has the original cams, There will be an "E" and an "I" mark on each cam.  These are to align with the gasket surface on top of the head.  If it has an exhaust cam with a flyweight on the sprocket, then you need to know whether it is an aftermarket cam made for a 426, or a Yamaha cam for a YZ450.  Most aftermarket cams will have some numbers stamped on them someplace, the Yamaha cams not. 

 

In the case of the aftermarket cams, there is usually a mark that will align with the head at "9:00 o'clock", and another at 12:00.   The Yamaha cam is more complicated: 

 

http://www.thumpertalk.com/topic/56257-yz-450-cam-mod-please-read/page-49#entry2979654

 

http://www.thumpertalk.com/topic/56257-yz-450-cam-mod-please-read/page-53#entry4458141

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0