HELP !!!! No YZ Timing for 03 WR250F ????

HEY ALL -- I just posted this on the WR250 forum... and decided to post it here also -- especially since I have a deposit on an 03 WR250... I mean, is a WR250 still a good choice...



After doing a TT search on "yz timing wr250f" -- I've just read that the YZ timing can no longer be done on the 03 WT250F. One sample statement:


One of the TT members reported a few days ago, that it doesn't work to change the 03 WR's timing to YZ position, as per the 01/02. The reason is that the 03's new auto-decompression cam will not develop enough compression to start.


Some say it can be -- with new YZ cams. Others -- if I scanned it correctly -- say the YZ cams cannot be used. One put it this way:


The YZ cam won't work for WR timing and the WR cam won't work for YZ timing. That is because the auto-decompression mechanism is installed at a different degree point on each of the cams. When you move the cam timing, the auto-decompression is activated at the wrong time effectively opening the exhaust valves too early (loss of compression) or too late (loss of easy starting).

You now have to buy the YZ for your WR.


Does anyone know for a for sure whether or not the YZ timing can or cannot be done for the 03 WR250F.

If YZ timing cannot be done for the 03 WR250F -- is an 03 WR450F a better choice for a NEW WRF buyer.



Yamsman, I haven't seen anywhere that anyone has verified this for the 450F yet, but I would bet that the same relationship exists between the WRF and YZF cams on the 450s. In other words, you'll probably have to swap out the cam on either bike if you want YZF timing on a WRF.

The '03 YZF cam for my 250F was $130 dollars. My WR cam works for YZ timing, but I'm getting the '03 cam to get the auto decomp.

Also, to clarify the above, it was later determined that the issue is not the degree position of the auto decomp mechanism. The cams are identical in this respect. The difference is actually just the size of the nipple that protrudes from the cam to open the exhaust valve. The WR cam has a larger nipple and when advanced to YZ timing causes the exhaust valve to open too far. See thread here

I wonder if someone may come up with a way to grind or reshape this part of a WRF cam to make it work for YZF timing?

So basically, you have $130 problem if you want YZ timing on an '03 WR. This might be compelling enough for some to reconsider a YZF instead of a WRF, but getting a 450F instead of a 250F proably won't change the situation.

Thanks neWRiver... I'll stick with the 250 and look into the cam issue further... after I receive the bike in a couple of weeks.

hey yamsman...

if the WR '03 cam and the no yz timing is bothering you that much y dont u just get a used 01 or 02?? i mean i dont know the specifics on the 03 cam... im thinkin bout getting 1 eventually but... i mean.. the WR timing is great and all but with the new cam... is it necessary... i havent ridden an 03 yet so im not shure what can and cant be done to it.. again.. stick with the 250 just because of timing u shouldnt assume that another bike is better :) its not the timing.. its the rider and the riders skill..... on a 250 in the woods my dad could beat some 1 on a 450... even with the timing at WR... its all where u ride.... the YZ timing where i am at is nice because the trails like to open in short straight boosts and i like to snap the throttle just a little bit... not that im a speed demon or anything :D as before the timing isnt every thing

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