Newbie Question on YZ timing

I purchased a 2000 WR400F second hand about 2 yrs ago and was told by the PO that a local dealership had YZ timed it.

The bike runs every bit as good as my friends WR450F that is not YZ timed.

I decided to give a try to changing the timing back to WR timing to see if it may suit my riding style and riding conditions. I researched it through the search function of the TT forum and it all looked pretty straight forward allowing about an hour to an hour and a half.

I pulled the timing plugs and rotated the engine to where the 'I' of the "HI" lined up with the marks on the sight window.Now's where I'm confused :cry:, both cam gears, Intake and Exhaust, punch marks appear that both the intake and exhaust cams are advanced (the punch marks on the left side of both gears are 5-6mm above the VC mounting surface and below the mounting surface on the right side). Is this possible?

Will taking out the tensioner alone allow enough slack for the chain to come of the crank gear and the timing be changed?

Am I reading too much into this easy task.Any help will be greatly appreciated!


OK, first, don't spend a lot of time worrying about where the punch marks are lining up with the head. This will only lead to frustration. Just make sure that the "I" in "HI" is aligned and that the cam lobes are pointing away from one another. Then count the pins to make sure that there are 12 pins between 12:00 marks (on intake and exhaust cam) for YZ timing. If you want WR, retard the exhaust cam 1 tooth in order to have 13 pins between 12:00 punch marks.

To answer your second question, no, taking the tension off of the cam chain will not let the chain drop off of the crank. If you remove the exhaust cam to retime, this is when it can fall off of the crank.


Let me start by telling you, you will be sorry for switching back to stock WR timing. The reason your friends 450 is not YZ timed, is because you can not yz time the WR450's. Remember he has a 450, you have a 400, may not seem much, but those extra 50cc make a huge difference, add in the fact they have different cams as well. Just my 2 cents worth :cry: :cry:

Actually, you can time a WR 450 to YZ time by changing out the exhaust cam. This however, would not be a free mod. :cry:

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