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jimbob69

Timing the yz400f hotcam.

6 posts in this topic

I've got a new auto-decomp hotcam that I am about to install, and I have a question. In the instructions from Hotcams it says NOTHING in the 7 pages of instructions on how to time it, sprocket to chain wise, they say nothing about where to put the pins or how to align the lobes or anything!!!

Would you just make the intake and exhaust lobes symmetrical from the right side of the engine like installing a 450 cam?

I'm pretty confused and I dont wanna make a stupid mistake :applause::ride::thumbsup:

Please respond ASAP because I would like to get it done with tonight.

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I'm going to assume that the cam has timing marks on it. Being an AD cam, it will likely only have two instead of the usual three. The two marks are the same as the original "E" mark, and the punch mark that went between the I and E. Use them exactly like the stock marks, by the procedure in your manual.

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Ok thanks for the reply, but it also bring me to another question.

The 2 dots on the cam sprocket are NOT 90 degrees from eachother.

So if you were to put one dot straight up, the other dot would be about 3/8-1/2 inch from the heads top mating surface, And vice versa, if you were to align the forward most dot with the mating surface, the other dot would not be pointing straight up.

im soo confused, the dots are not 90 degrees from eachother like a stock cam, they are much closer to eachoter, probably 75-80 degrees.

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I think that, absent any instructions to the contrary, I would still line up the "9:00 o'clock" mark with the head surface as if it were the original "E", and not worry about the "12:00" mark.

You should, once this is done, still have a noticeable amount of compression as you crank the engine, but you should be able to kick it straight through compression, too. The compression behavior is a kind of a giveaway as to th right cam timing because the timing of the decompression mechanism is affected by the cam timing; too far advanced, and it has too much compression when cranking, too far retarded it has too little to start.

You can contact Hot Cams directly to clear this up, or maybe someone who has installed HC's in their 400/426 has seen this and knows for sure.

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I've got the Hot Cam in my 02 426. Just line up the 9 o'clock mark with the head. If you are not sure, check from the other side... the lobes will be pointing at approximately 10 and 2.

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