Camshaft Installation Timing Question

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imandrewparks
Posts: 7
Joined: Thu Feb 11, 2016 11:48 am

Camshaft Installation Timing Question

Postby imandrewparks » Fri Jan 20, 2017 3:11 pm

Hey everyone! After replacing the starter clutch in my 1981 CB650, I finally got it started to then realize Cylinder 1 and Cylinder 2 weren't firing. I've checked the carbs, and ignition. I'm definitely receiving fuel and creating spark. I then checked compression and Cylinder 1 and 2 read slightly low, so I'm curious if there is a screwed up valve, or bad rings. Let be me forthcoming in saying this is going to be my first engine teardown.

I have successfully removed the head cover, and the cam. Once my buddy comes over I can get him to hold the cam chain that I have wired to the frame while I remove the head.

The reason I am posting this is because I am nervous about the re-installation of the camshaft. I have a basic understanding of how the engine works, but am certainly novice when it comes to correcting timing, etc. Please excuse the potentially stupid questions I am about to ask.

1.) How do I make sure I am putting the cam in correctly? Is there a certain way the lobes should be facing up vs down vs horizontal? Does it matter as long as the notch is horizontal with the head?
2.) Is there a certain way the sprocket should be installed? I don't mean which side do you slide on to the cam, or which side of the sprocket faces out/in, but what I'm asking is rotational direction. Is there a top or bottom to the cam sprocket that needs to face up or down?
3.) Is there such thing as the cam being at TDC? Or is that simply just referring to the pistons?

Please drop any tips or other suggestions you may have for a noob like me. Thanks so much!

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Folsoml
Posts: 1634
Joined: Sat Apr 07, 2012 9:02 pm
Location: North Florida

Re: Camshaft Installation Timing Question

Postby Folsoml » Sun Jan 22, 2017 9:20 am

All these things matter, and they are very important. Check out this post in the general discussion forum that has a link for a workshop manual.

viewtopic.php?f=3&t=9850
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tario
Posts: 166
Joined: Sat Mar 07, 2015 2:26 pm

Re: Camshaft Installation Timing Question

Postby tario » Fri Jan 27, 2017 11:21 am

When you put the cam shaft in on 1979-1982 engines there is an alignment notch on the cylinder 4 end. The cutout should be facing forward, it should line up flat with the surface of the head. Engine has to be in 2.4 T position. (this should be rotated at the timing switches/points. (technically not points)) Your sprocket should just line up if you have done this right, you might have to fiddle with the chain to rotate the sprocket though.

Manuals should have better instructions/pictures.
1979 cb650
1980 cb650


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