yz450 using yfz cams

[michae engelhardt jr]

i bought a stock complete head off from a yfz450 and having problems should i buy a new exaust cam or what should the timing be if it will work with them cams any info will be appreciated if the timing is advanced is that clockwise or counter clockwise

[mx4god]

Are you saying you want to put the atv cam in the bike head? If it's the same year then it should work because the yfz450 has the same engine as the yz450f.

[KJ790]

I believe the YFZ comes with the same exhaust cam as a WR450F since it has electric start. Put in an exhaust cam for a YZ450.

[grayracer513]

The YFZ did in fact use the same cam as the WR450 in the first couple of years, but it was done to soften the power more than for the electric start. If you want to loose 4-6 hp (but have a smoother running engine at low speeds) use the YFZ cam. Otherwise, use the exhaust cam for a YZ450, like KJ said.

[KJ790]

The YFZ did in fact use the same cam as the WR450 in the first couple of years, but it was done to soften the power more than for the electric start. If you want to loose 4-6 hp (but have a smoother running engine at low speeds) use the YFZ cam. Otherwise, use the exhaust cam for a YZ450, like KJ said.

yeah, the only reason I said it was for the electric start is because the YZ and the WR have different length decompression pins (as well as their other differences for performance purposes). If you buy a hotcam for it, they offer one for a YZ, and one for a WR/YFZ. These are the same cam with the same profile and timing, but the WR/YFZ one has a different decompression pin for the electric start.

[grayracer513]

The different pin lengths are to compensate for the difference in the YZ/WR cam timing. The early models of both bikes used the same camshafts, but they were indexed into their sprockets differently, the WR cam being more advanced than the YZ by roughly 20 degrees. The pin was extended so that the exhaust valve would not reseat 20 degrees too soon during auto decompression.

[KJ790]

The different pin lengths are to compensate for the difference in the YZ/WR cam timing. The early models of both bikes used the same camshafts, but they were indexed into their sprockets differently, the WR cam being more advanced than the YZ by roughly 20 degrees. The pin was extended so that the exhaust valve would not reseat 20 degrees too soon during auto decompression.

That's what I thought, but when I asked Hotcams what the difference was between their cam for the YZ and their cam for the WR they told me that they were exactly the same when it came to profile and timing (gear indexed on the cam exactly the same), but the decompression length was different to make it easier for electric start vs. kickstart. I don't know if it is true, but that is what they told me.

[grayracer513]

Unless they have a mark on the sprocket for timing a WR, and another one for timing the YZ, that has to be wrong. Then again, you never know who you're going to get when you do phone support.

[michae engelhardt jr]

which direction is advanced clockwise or counter clockwise

[grayracer513]

Advanced is farther forward sooner, so it is counterclockwise from the sprocket side. If you are thinking about just re-timing the cams to compensate, don't. If you retard the exhaust cam, the auto decompression mechanism will close too late, and the bike won't have enough compression to start.