Cam timing basics made easy


6 replies to this topic
  • ready fredy

Posted November 01, 2008 - 04:48 AM

#1

over the years i have seen many questions about cam timing and how easy it is to be just one tooth off, I borrowed my friends 426 manual and actually its very easy to do right the first time. according to Yamaha the only marks you need to use is the mark closest to the carb on the intake cam and the mark closest to the header on the exhaust cam. Not trying to get all three marks on both cams to be perfectly aligned. And it works every time for me. But i have a bit of advise here, An easy mistake is to be looking down at the head while doing this and you can easily make the mistake of being one tooth off, You MUST be at eye level with the marks while setting the timing, Just another note this DOES work while installing newer cams in older bikes too the proper marks will align just fine. I hope this helps

  • bperry4

Posted January 15, 2009 - 10:28 PM

#2

I have a wr450f and tried these settings, the bike still cannot start... from the number of times I've been setting this, I've gone nowhere with this.

  • KJ790

Posted January 15, 2009 - 10:34 PM

#3

The biggest mistake people make is setting the timing with the chain tensioner out, and never rechecking it after putting the tensioner back in. Without tension on the chain, it will slack slightly between the cams. When the tensioner is put in it takes up this slack and the intake cam will roll backwards slightly, often revealing that the timing is actually off by one tooth on the intake cam.

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  • SJMC_DON

Posted January 16, 2009 - 07:51 AM

#4

The biggest mistake people make is setting the timing with the chain tensioner out, and never rechecking it after putting the tensioner back in. Without tension on the chain, it will slack slightly between the cams. When the tensioner is put in it takes up this slack and the intake cam will roll backwards slightly, often revealing that the timing is actually off by one tooth on the intake cam.


Bingo!!!!!

Below is a Grayracer post I copied to a word doc. and actually placed in my manual... it explains this and gives a simple procedure for avoiding it:thumbsup:

[COLOR="Navy"]The next thing that must be looked at in timing cams is that the crank can turn nearly 10 degrees without moving a cam if the tensioner is off the engine. When you think you have the engine timed, rotate the crank backward until it starts to move the intake cam, then manually rotate the exhaust cam back until it draws the chain tight, and then do the same to the intake. After that, rotate the crank forward until it arrives at TDC again. This will pull both cams into the actual position they would be in were the engine running, with the front and top runs of chain drawn tight. See what the marks look like in that position. Not doing this screws a lot of guys up.

[/COLOR]


  • bperry4

Posted January 18, 2009 - 05:28 PM

#5

ok thanks, but from the crank there are three(3) marks, which is the right one to use??:thumbsup:

  • bperry4

Posted January 18, 2009 - 07:45 PM

#6

Working on this bike is a very new thing to me, and I will need ALL the help I can get to run this machine hard to it's core. thanks in advance...:thumbsup:

  • bperry4

Posted January 26, 2009 - 09:10 PM

#7

ok, I think I have all the settings right now. but why won't it just start?? is there something I need to check apart from the timing?

My wr450f was a running bike until it started discarging coolant from it's over flow hoses, and I mean ALL the coolant. replacing the head gasket should have done the trick but now it won't fire at all...it has all vital components (fuel,oil,air,spark) but still cannot stat...

Am I missing something???
thanks




 
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