Did I do this YZ cam conversion correctly?

Hi all; I posted this in the WR forum too, but I'm hoping someone over here might know as well!

Just put the 2004 YZ450f cam in my 2004 WR 450 tonight; Clearances came out all right; but on the new (YZ) exhaust cam, the 'punch marks' are placed differently than the old WR cam. The question is, do I use the lower punch mark and line up up with the top of the case, or do I make sure the upper punch mark is in the same place on the chain as the last was?

If I place the upper punch mark on the same place in the chain the old one was located, the lower mark is not placed correctly on the case.

Here are some photos of what it looks like installed.



I've read 12, 13, and 14 marks; but I can't seem to find a definitive answer on this anywhere!

Well, I'm even more confused now, if that's possible.

I just looked at a manual from a 2004 YZ450f; in the diagrams in valvetrain and cams it shows 14 pins between the two marks. Unless they just use generic diagrams for all the manuals, then that would put my exhaust cam lower pin below the case...


It looks like your exaust cam sprocket needs to be a tooth forward, your intake one looks fine.

1 tooth counterclockwise

Ok; so the exhaust cam lower mark will be below the case normally? If I rotate it counterclockwise one tooth, then the lower mark will not be visible, it will be below the case. That is normal?

I'm not certain of whether the "12:00" timing marks on a YZ and WR intake are in different positions, but the manual for a 450 simply states that the two horizontally oriented marks, at 9:00 on the exhaust and at 3:00 on the intake, should be aligned with the head. It makes no mention of counting out chain pins.

Remember that both the cams in your engine were intended for the head they are in, even if they were not intended to be in a pair with each other. So, the timing is a matter of aligning both cams correctly relative to the crank, which the 9:00 and 3:00 marks will accurately do in this case.

Counting pins is important when swapping the '03 cam into a 426, since it uses a different head casting.

Greyracer; thanks for the information... So by looking at the photos, it looks correct to you?

As a matter of fact, I just finished up replacing the timing chain and flywheel in mine, and before I took it apart, I checked the timing mark alignment. With the 9:00 and 3:00 marks aligned with the head as prescribed, there are 13 pins between the two 12:00 marks, just as in your photos. Looks perfectly right, assuming you're at TDC. :)

Sweet! Thanks Greyracer. I'm at top dead center, I hope! There is a horizontal H mark on the flywheel, and an "I" directly to the right of that. That is where it is placed.

Yep. The "I" is TDC. The "H" is the ignition timing mark.

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