WR-YZ timing

I recently replaced my 2003 WR cam with a YZ cam, the bike is a pig to start now when cold. It seems to rich as the throttle has to be held open a little or it just will not start. It fires but won`t pick up revs to an idle speed. The engine also bogs when the throttle is cracked wide open, WR`s do this but it is much more noticeable now with the YZ cam. Other mods, ported head, full exhaust, opened up air box and twin air filter. I have been reading about the air cut valve mod as I already have changed the jetting to YZ specs. The Australian models show the "Grey" wire so i am also going to try cutting it.

are you sure you timed it right?

sounds like your timing is off. Go back and check it out. <M> :applause:

I agree with above, recheck the timing.

I did the same to my 03 and it starts better than with the WR cam. 1st kick every time now.

Mine is a canadian model and the grey wire goes to ground on it as well. I wasn't sure if it would make a difference so I put a switch in the line so I could go back and forth to see the difference.

I road race mine and went out for a session with the new cam but using the WR switch position(still grounded). I honestly didn't think it was any better than with the stock cam.

Next session flicked the switch and could not believe the difference. Completly different bike up top. Major difference, will never go back.

John R

I also have a canadian 03 and I am very happy with the cam swap, I think the bike has more response down low which is great but no more power really overall just comes on sooner, I guess I should consider the grey wire mod? also I usually have to twist the throttle 5 or 6 times before start up then if it does not fire right away I do that again, I even have the throttle cracked a touch while cranking over. It would be nice just to touch the button but my WR seems to need a bunch of gas to even think about firing. Every once in a while the starter finds a dead spot or high compression spot and it will not crank over with the electric starter so I have to give it a small hard kick, then it will crank over again, never had that happen before cam swap.

Yeah guys, I have checked it a couple of times now!! Are the YZ`s timed the same as WR`s...cam marks to the outer cylinder head upper surface and the T.D.C mark. I`m not sure what else it could be. I am trying jetting at the moment. I have heard that the YZ cam makes the starter system work harder so this maybe my starting fault, just need to get rid of the flat spot when the throttle is cracked.

Every once in a while the starter finds a dead spot or high compression spot and it will not crank over with the electric starter so I have to give it a small hard kick, then it will crank over again, never had that happen before cam swap.

Mine too!! Seems they all seem to have a few of these common probs, dont know if there is anything wrong or if its normal though :applause:

I have had the same problem also since installing the YZ cam. The bike will not start hot or cold with the button.Though starts first go with the kick starter.

The YZ cam should be installed just as if it were the stock cam, I believe the timing is roughly one tooth different but you still line up the marks to the case on install and the end result is an advance in timing. One of my friends swapped out the decompression button from the WR cam to the YZ, it seemed in his case to help, there wasn't much difference in size but there was some, for whatever reason my WR doesn't have much of a starting problem I think the flat spot I hit could be due to the decompression button difference. It happens so infrequently that I'm not worried about it. No flat spot.

So guys lets assume the starting problem is caused only by me being slack and only using the button...looks like i may have to put the kick starter back on. Has anyone had the flat spot problem, if i only open the throttle a 1/4 it couldn`t be better is only when i crack it wide open from low in the revs. This is where it is most noticable in comparison to the WR cam, It runs a bit rich on top but i don`t mind that, 190 main. Needle clip raised one position,45 pilot,screw out 2 turns as per YZ specs, again this was fine until the YZ cam was fitted. I know just ride it harder but down low is wheel stand area!!

190 main?? :applause:

I'm surprised it even revs out!

I used to run a 170MJ with the big DSP header, but had to drop to a 165 with the gytr pipe. Now with the de-ported head I'm down to a 158.

Who with 98-02 WRs is still running on wr timing? Is the difference between wr and yz timing great?

I sold my YZ timed 99 400 in January 05..wish I had kept that bike..Yes YZ timing makes a world of difference, once properly jetted.. :) and un-corked. I still believe it was faster than my 05 450 :applause: more low end snap also..Make the change and don't look back. Use a AD450 cam and it will make a new beast out of it.. :eek:

i have an '04 450 with the hotcams fitted and i've never had a drama with the kick or e-start because of it, i'm inclined to think its a jetting drama more than anything else but who knows its just my 2 bobs worth.

for ****s sake dont cut the grey wire!!!!!! thats your rev limiter!! cut it, pin it and watch it go bang in a big way

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now