Decompression cam


6 replies to this topic
  • woodsk

Posted February 19, 2004 - 10:43 AM

#1

Ok, I am sure this has been asked before, but I could not find the question for my specific bike so here it is agian--
I have had my '00 WR400 for about a month now and I am already sick of the decompression lever. Who makes a decompression cam for a '00 WR400. Secondly I have been one of those guys that has my shop do most of my non free mods to my bikes but would like to start turning wrenches my self, would this be too big of a job to start with?

Thanks
Kerry

  • tcmII

Posted February 19, 2004 - 03:16 PM

#2

First, there are a number of options for a auto decompression cam available. It seems that the two best choices are the Yamaha dealer, '03 YZ cam $140.00, '03 WR cam 180.00 (based on local Michigan dealer), or Hot Cams makes a auto decompression cam. Also, you will have to choose a cam, you can not "re-time" a '03 WR cam to YZ timing without effecting the auto decompression function.

There is some debate regarding using the Yamaha cam in older versions. There are numerous threads of great length on the YZ side. I also have downloaded some installation information, if you need it you can PM me. I just bought a used WR400 and I haven't spent enough time yet to decide what to do.

Second, If you are fairly mechanically inclined you may be able to do the install. The work it self is not much more than required to check the valve shim clearance. The difficulty is that the Yamaha cams are not properly marked for the early models and you have to carefully follow the directions to get it right. I suggest that you also look at "thumperfaq.com".

Lastly, please keep in mind that you need to make your own decision. Free advise is worth what you pay for it, with no refund.

  • Hamish

Posted February 19, 2004 - 07:28 PM

#3

It isn't a hard mod to do, but the potential for carnage is very high if you get it wrong. When any top end work is done it's very important to turn the engine over slowly by hand using a socket on the crank. I know of a guy that recently snapped his expensive titanium valves from kicking over his newly assembled engine without first testing for clearance.

my 2 cents worth,
Hamish

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  • Matt96xr6

Posted February 19, 2004 - 07:42 PM

#4

you can not "re-time" a '03 WR cam to YZ timing without effecting the auto decompression function.


Not true. you can change the timing. CHeck out the YZFCentral site (450 quad), there is a writeup of how to do this. They are changing to the YZ timing.

But either go YZ450 cam or Hotcams.

  • John_H

Posted February 19, 2004 - 08:08 PM

#5

Not true. you can change the timing. CHeck out the YZFCentral site (450 quad), there is a writeup of how to do this. They are changing to the YZ timing.



I'm not familiar with the info you're talking about. After putting in a YZ auto decomp cam in my WR426, I understand why the decomp cams aren't interchangeable.

What am I missing??? Give me a link to the info you're talking about. :)

  • blue_beast_wins

Posted February 19, 2004 - 09:13 PM

#6

you can not "re-time" a '03 WR cam to YZ timing without effecting the auto decompression function.


Not true. you can change the timing. CHeck out the YZFCentral site (450 quad), there is a writeup of how to do this. They are changing to the YZ timing.

But either go YZ450 cam or Hotcams.




I was under the impression that the YFZ's have different ex cams but i havn't checked the part numbers :)

  • Matt96xr6

Posted February 20, 2004 - 05:44 AM

#7

I have heard claims that the WR and the YFZ is the same cam. That came from a magazine before the YFZ was released. I could not tell you either way if this is true or untrue. What I can say is that the WR, YZ and YFZ exhaust cams are all different part numbers (as of last week).

Here is your link for the cam mod on the YFZ:

YFZ Cam timing modification




 
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