honda CB125 question

 Happy Thanksgiving! If anyone can help with this...

I have a 74 CB 125. I'd like to adjust the timing chain. As I understand
the manual, one tightens (screws in) the adjusting screw, which is
supposed to tighten the chain. However, in talking to a guy who once
rebuilt his motor, he reports that the manuals are backwards--that
LOOSENING the screw actually tightens the chain. He said he found out
the hard way after his chain gave out and he did the rebuild. Once the
motor was apart, he discovered that the screw must be loosened to
tighten the chain, and by tightening the screw he had actually been
slackening his chain.

Can anyone give a certain answer on this one?

 


It's been a *real* long time since I fooled with a timing
chain adjustment, but as I recall, it's done as follows:

1). Remove the engine side cover noted in the manual.
    As I recall, this was usually the side cover where the
    contact point mechanism was located. This removal
    is necessary to turn the crankshaft, and sight the marks
    for crankshaft alignment.

2). Following the manual, rotate the crankshaft until the
    noted alignment mark(s) have been reached.

3). Loosen the lock nut on the camshaft tensioner bolt.

4). Loosen the camshaft tensioner bolt just enough to
    be finger loose.

5). Although not in the manual, I always used some
    small object to tap on the cam tensioner housing
    to ensure it was free to reset.

6). Retighten the cam tensioner bold to manufacturer
    torque specifications.

7). Retighten the cam tensioner lock nut to specifica-
    tion.

That's the way I recall it.

Again, as I recall, the cam tensioner consists of a spring
and a rod. You spin the crank to a no-load position,
loosen the set bolt on the tensioner, allowing the spring
to push further into the now slack chain, and then you
retighten the whole assembly.

 

Anonymous wrote:


There is NO spring in the cam chain tensioner on a 1974 Honda CB125S1.

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Anonymous wrote:

That's true for a lot of models, but these little motors had a weird
sort of setup, with kind of a bowed shaft that they used. What your
talking about is right for like a 350, but I think the 125s do not use a
spring-loaded rig like other models. Wish they did

 vince garcia wrote:


This is a typical Honda design where they have to do things differently from
what everybody else does.

The cam chain rubbing block pivots at the top, instead of the bottom.

Tightening the bolt makes the rubbing block bend, by pulling on it from the
bottom.

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