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Cam position when at TDC

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I am putting a new head on my sons XR70 and can't seem to get it right. I tried to order a head from TB but they were out so I got one from DRATV. Can't figure out if something is wrong with it or what is happening. It almost seems like the mark on the cam gear is off.

I can get the bike to run like crap but if I set the bike at TDC and the cam gear at 9 oclock I get nothing. The valves are adjusted to .004.

Where should the cam be vs the lifters when the engine is at TDC?

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The cam lobes should be pointed down, toward the top of the piston, the valves will then be closed.

Try an intake valve adjustment at .002", and the exhaust at .003", those are factory settings.

Also, try setting the "T" mark at 12 noon (TDC) first, then adjust the cam sprocket a tooth at a time so that the "o" mark is at the 9 o'clock position, or just a hair to the high side of the alignment notch in the head.

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Thanks, I'll give it another shot tonight. I think I have been close but after reading that I'm pretty sure the mark on the cam sprocket is in the wrong spot.

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Go over what dirtbkr188 said [or print it out and take it out to the garage with you] Sometimes I find it helps if I take a 1/2 hour break when things aren't going so well, then when I come back it's much easier to see what I have overlooked. Let us know how you make out.

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Yep, I went out last night and 5 minutes later it ran fine. Just needed a second set of eyes.

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Yep, I went out last night and 5 minutes later it ran fine. Just needed a second set of eyes.

Awesome!! 👍

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