Vintage and Classic Hondas

How do I get the cam chain adjusted correctly?

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83seebee

How do I get the cam chain adjusted correctly?

So... my bike (83 cb750sc) had a horrible rattle that got really bad at certain rpms and turned into engine vibrations at 5k and a really loud rattle at 7k. i loosened the cam adjuster nut a bit and tightened it back down and all these problems went away, along with the throttle hang and it has at least twice as much power between 1 and 3k. Its feels like a brand new bike now. the only problem is I have no idea how the adjuster works and i noticed a couple new, much less noticeable rattles at different rpms. the manual says to let it idle, back off nut half turn, tighten, and repeat for rear adjuster. Is it better to do it with the bike off, cranking it manually? and can anybody explain how to do it properly? How do you know when to stop tightening the nut down? I would like to get this thing dialed in to perfection. any help much appreciated!

83seebee

Re: How do I get the cam chain adjusted correctly?

well... did some reading... sounds like these auto adjusters kinda crap out on high mile bikes? just so i know if I'm doing it right, are you supposed to stop tightening the front when you feel resistance or do you just crank it down tight?

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Re: How do I get the cam chain adjusted correctly?

Administrator

In reply to this post by 83seebee

I have never done a DOHC cam chain, but I do know that they are prone to guide/tensioner failure when they get a lot of miles on them. I would check the guides.
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1977 CB 750-A X 4
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LukeM

Re: How do I get the cam chain adjusted correctly?

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The cam chain adjuster on my 79 model was probably what caused the cam chain failure. Upon inspection, the nylon/plastic part of the adjuster (that rubs against the chain) had worn away, so it was metal on metal in spots. Also, with the chain whipping back and forth, it put a perpendicular groove in the channel in the head.

The only downside is getting to it without taking the motor all the way apart. It may be possible to inspect and/or replace it by removing the head. Check the FSM for your bike/motor and see what it looks like.

Good luck. Finding and fixing it now is gotta be cheaper than a teardown/rebuild because something inside went *boom* or *snap*.

Luke M

Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.