cam mod

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#1
I was wondering if I can perform the same cam mod on my 04 YZ450F that is being done on the YFZ450s? My bike is down for repairs right now and since I have it down I want to perform this mod. But I want hear from you guys first. It seems I should be able to do it since the motors are similar and if it doesn't work I can change it back without any ill effects.
 

Rich Rohrich

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#2
What cam mod are you talking about?
 
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#3
The cam mod on the YFZ retards the exhaust cam 1 tooth, giving it YZ450 cam timing instead of WR450 cam timing. This disables the auto-decompression, but that's not much of an issue on the e-start YFZ.

[It's been nearly 4 years since I performed the mod, and I think the mod retards it one tooth, but it might be advancing the cam 1 tooth- not 100% sure which one it is].

By leaving your YZ's cam timing stock, you'll already have the cam timing YFZ owners want.
 

Rich Rohrich

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#4
Matt Fisher said:
[It's been nearly 4 years since I performed the mod, and I think the mod retards it one tooth, but it might be advancing the cam 1 tooth- not 100% sure which one it is].
You have it correct. WR450s have the exhaust opening advanced ~23 crank degrees (1 tooth) compared to a YZF . They did that to start the blow down early as a way to work around the restrictive OEM exhaust system. I just didn't realize they used that oddball timing on the quads as well.
 
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#5
I tried it and it didn't work on my yz450f. it wouldn't start after I did it so I put it back and now it runs fine. I had figured that where it is now is where the yfz owners want it. so I am going to leave it where it is unless I change to aftermarket cams in the future. No harm,no foul in trying. live and learn.