yz426 auto decomp cam teeth dont fit perfectly with timing chain?

5 replies to this topic
  • Octanee

Posted July 18, 2012 - 08:57 PM


hi guys, so basically, i found out on this 426 i got the exhaust bearing to the cam was fried, i went to pick it up by the bearing and wth all this slop! so it was time to go auto decomp... local dealer had some cams, so i sent my friend down, NOW from reading, im told 03-05 Yz450f exhaust cam.... correct? what about Wr's?

i ask this because basically the guy told my friend (and its his dbike) that, that cam should work.... i notice size wize its a bit smaller i think on how big the gear is, like top of both gears is no longer nice and paralell but a slight grade uphill from exhaust to intake cam....

so should i run this cam? the Timing chain doesnt want to really sit that well into the teeth on that cam, its a new wiseco timing chain i had bought, but the stock intake it fits alright on....

so, basically the guy at the yami here that sold it said it would work, he said it was off a "yz450f" but didnt say what year... (could it actually be a wr cam?)

. Anybody got any ideas? should i run this? the chain DOES bite into the teeth a bit, that i could see it working fine, but im just trying to make sure before i go ahead and do all of this up.... and find out it skips a tooth magically or w/e, THANKS!!!

  • grayracer513

Posted July 19, 2012 - 06:44 AM


The information you need is in this thread:


If you haven't read every one of the 1119 posts in that, I'm not really surprised. Your question regarding the chain was one that came up 10 years ago when people started tinkering with this conversion. It's true that the chain "doesn't fit right". The pitch is actually the same, but the tooth profile of the newer cam is different. No one has had any problems with this particular issue in all that time, however, so you needn't worry about that part of it.

Remember that timing the cams will not work like the stock setup. The valve angles in the 450 head are different, which means the cam sits in a different place, which means that the marks for the 450 head won't line up with the 400 head if it's timed right. Read these two posts for more info:



  • Octanee

Posted July 19, 2012 - 03:54 PM


i got it all in, i forgot about the intake cam first then count 14 pins, thanks again grey!

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  • essex426

Posted July 20, 2012 - 03:49 AM


Just out of interest,does anyone know if its worth trying this with a WR450 cam.
I used a YZ cam in my 426 several years ago, and liked it.
A friend still has a yz 426 and would like to try a decompressor cam, and i happen to have an unused 04 WR450 cam.
Dont want to waste time,if its not a good idea,it does not warrant sending money on.

Thread hijack sorry.

  • grayracer513

Posted July 20, 2012 - 07:04 AM


WR cams will slow the bike down considerably. Probably cost about 5 horsepower, maybe more.

  • essex426

Posted July 21, 2012 - 10:52 AM


WR cams will slow the bike down considerably. Probably cost about 5 horsepower, maybe more.

Ok, thanks for the reply.
Will tell him not a good idea then.

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