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  1. #1
    CB750 Member flatpick13's Avatar
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    Could use a little help, issue with exhaust cam sprocket punch alignment!

    I'm reinstalling my cams, with the crank at 1.4 - T and my exhaust cam installed with the #1 cylinder lobes pointed towards the spark plugs, I can see the sprocket punch marks above the head, but they don't align perfectly. They're probably closer to parallel with the floor than parallel with the head, but if I make the sprocket punches align perfectly with the head the lobes for the #2 cylinder are propped against the valve shims and the cam shaft isn't seated...

    Anyone have any suggestions? Do the sprocket punch marks need to be perfectly aligned with the head? I'll grab some pictures and post in a follow-up to illustrate my predicament...

  2. #2
    CB750 Guru amc49's Avatar
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    Need to be very careful when comparing head angle to the floor. Meaning your engine better be level like in bike.

    Only new chains come close to lining up, if old they will be stretched and the cams slightly behind (retarded) then, meaning you could be correct there if looking at engine from the LEFT side. You have to install the cam caps to pull the cams down solid, there is no place on engine where at least one cylinder will not be hitting cam shims.

    Try to split the head with the marks but if sprocket mark only seems to go in at too far counterclockwise or too far clockwise then use slightly too far clockwise as your ending spot. If not you will be in wrong by one tooth.

    The chains stretch with use making the marks fall back, correct will be hitting the 1-4 mark and then you have to turn engine slightly a bit more (clockwise on ALTERNATOR SIDE of engine!) for marks to split head. That effect is worse the older the chains are. You do not use the left side of engine for turning it at all.

    The exhaust chain stretches more as it is longer, the intake may be dead on or off less, but make it same way if there is any question.

    Consider as well any lobes touching shims can shift cam around to alter what you see, why caps need to be in place for final check and the tensioners can too so multiple rechecks are need as you alter those things.

  3. #3
    CB750 Member flatpick13's Avatar
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    Thanks, amc. I got it lined up, had to pop the exhaust cam sprocket off while the cam bearing caps were installed so the cam didnít shift while I lined the chain up. Kind of a pain getting the chain/sprocket back in place with the cam secured, but at least that parts done.

    Follow up question, there were no rubber oil caps in the head when I opened it, I have some on order now, but what purpose do those serve and how important are they?

  4. #4
    CB750 Guru amc49's Avatar
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    They direct oil slinging off chain and sprockets into the cam lobe pockets which fill with oil to let lobes dip into them to sling oil over parts. Whenever you rebuild top end you fill those pockets with oil just before cover goes back on.

  5. #5
    CB750 Member flatpick13's Avatar
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    Ok, thanks!

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