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First time doing a valve check myself...Questions.

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First time getting this intimate with an engine before, so everything is new.

In the manual it says "In order to be sure that the piston is at Top Dead Center, the punch mark © on the exhaust camshaft and the punch mark (d) on the intake camshaft must align with the cylinder head surface, as shown in the illustration."

photoyqs.jpg

By wdthfxup at 2011-05-22

Mine doesn't line up quite like they're saying it should. Is this typical? Should I go off the cams to determine TDC, or the crankshaft?

img1618o.jpg

By wdthfxup at 2011-05-22

Showing I was at TDC via the crankshaft marks;

img1615ic.jpg

By wdthfxup at 2011-05-22

Other pictures I took.

img1625o.jpg

By wdthfxup at 2011-05-22

img1624h.jpg

By wdthfxup at 2011-05-22

img1622r.jpg

By wdthfxup at 2011-05-22

img1621ka.jpg

By wdthfxup at 2011-05-22

img1620wr.jpg

By wdthfxup at 2011-05-22

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You have it on the wrong flywheel line. there are a few and you want the one after the H. also the cam lobes should be facing outward.

here for pics....http://forums.dirtrider.com/70/6595328/yamaha-dirt-bikes/valve-adjust-procedure-for-yz250f-yz400f-426f-450f/index.html

edit... also the E and the I on the intake cam stand for Exhaust and Intake. E should be facing toward the exhaust cam, Intake towards the back.

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You have it on the wrong flywheel line. there are a few and you want the one after the H. also the cam lobes should be facing outward.

Thanks, got them lined up now. When the flywheel is lined up on the correct mark, the camshaft marks are not exactly aligned with the crankcase cover. Should I get these perfectly lined up, or should I just go by the flywheel mark?

Edited by wdthfxup

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the cam dots are not perfectly aligned with the head, if they flywheel is on the line, the cam lobes are facing out and the dots are close you should be fine.

if you really want to double check, do the old screwdriver method, just take a long skinny screwdriver and put it down the spark plug hole and feel when its at the top of the stroke.

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If the dots are almost aligned like the intake is perfect but the exhaust dot doesn't line up and less than a tooth off you are fine. It's a sign that your cam chain needs to be replaced

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Could it do any dammage to a bike if you were to turn the crankshaft over clockwise in order to get the punch mark lined up?

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Depends on how far off they are. If it's off less than a tooth no damage but if it's off by a lot then the piston will smack the valves

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