quick timing question on cam swap


9 replies to this topic
  • tribalbc

Posted October 13, 2009 - 11:47 AM

#1

I'm installing some 08 YZ cams in my 07 WR.
Crank is at TDC.
Intake cam marks line up perfect.
Exhaust cam marks seem advanced one tooth.
When I removed my WR cams I counted 13 pins so that is what I have between my YZ cams.
So if I set up the Exhaust with what looks right there will only be 12 pins between :bonk:

  • tribalbc

Posted October 13, 2009 - 12:01 PM

#2

Here's some pics. They're pretty bad but hopefully you can see.

Intake



Posted Image






Exhaust



Posted Image

  • Wiz636

Posted October 13, 2009 - 12:10 PM

#3

Since both timing marks are positioned mid-link I'd say you have 14 pins between them from the pics.

  • grayracer513

Posted October 13, 2009 - 12:16 PM

#4

I can't see anything in those pictures. Either look into the "Macro" function on your camera, or back away and zoom in.

The important thing is in how the cams relate to the crank, not how they relate to each other, so go more on the alignment of the timing marks than by the inter-sprocket pin count.

Try again with the pictures.

  • tribalbc

Posted October 13, 2009 - 12:23 PM

#5

Since both timing marks are positioned mid-link I'd say you have 14 pins between them from the pics.


Both my WR cams were mid link. Did I miscount that as 13 then when it was really 14 ? And now the YZ is 13..
It would make sense alighnment wise.

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  • tribalbc

Posted October 13, 2009 - 12:30 PM

#6

WR timing


Posted Image





YZ


Posted Image

  • Wiz636

Posted October 13, 2009 - 01:08 PM

#7

You need to rotate the exhaust cam back one tooth. Also, if you are using the same cam chain that is in the WR pic then you'd better replace it...it is kinked.

  • tribalbc

Posted October 13, 2009 - 01:11 PM

#8

You need to rotate the exhaust cam back one tooth.


Thanks, I guess it's one tooth less than the WR timing.
This looks about right I'd say







Posted Image

  • tribalbc

Posted October 13, 2009 - 01:11 PM

#9

You need to rotate the exhaust cam back one tooth. Also, if you are using the same cam chain that is in the WR pic then you'd better replace it...it is kinked.


It's a new cam chain :bonk:

And actually it didn't feel kinked anywhere. It was smooth but stretched. Wr pic is no chain tensioner. First YZ shot is tensioned.

  • grayracer513

Posted October 13, 2009 - 02:34 PM

#10

Again, it's the timing marks at 9:00 and 3:00 that are important. Rotate both cams and the crank a few degrees clockwise, then rotate the crank forward to TDC and check the marks again. They look like they are probably correct, but double check them anyway, then check again when the tensioner is in.





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