CB125S camchain adjustment question

The camchain adjuster on these little lumps (1972 model) is on the
left-hand crankcase half. what looks exactly like a screw and locknut
assembly - 14mm locknut, and threaded adjuster poking through it wth a
slot for a screwdriver blade.

Irritatingly, I've only got a Haynes BOL of the CB100N. Same engine, but
that has a 10mm headed bolt poking through the locknut. BOL says to set
engine to fast idle, undo locknut, retighten, tensioner does the rest.

Presence of screwdriver slot suggests earlier model is slightly
different. I tried loosening off the locknut, wth engine set to TDC, so
obviously not running, and slackened off the slotted adjuster.

The usual procedure with these things, from clutch to camchain
adjustment, is to tighten carefully until you feel resistance, back off
a quarter of a turn or so, and do up locknut. But twiddling it one way
or t'other felt exactly the same, so I reset it to its original position
and re-tightened the locknut.

Has anyone got a manual giving the definitive procedure for an old CB125
single? Or does anyone know for sure? The engine sounds sweet - I only
decided to check the camchain as I was doing the tappets - but it would
be nice to know for future reference, as it were.

 

The Older Gentleman <> spewed forth the
following...

Lesson #1 in Usenet.

Read the post you are replying to in full before you spend a patient 10
minutes copying text relating to all things camchainy from the Haynes BoL
for Honda Twins (CB125/160/175/200/SS125/CD175), along with a further 5
minutes personal experience and notes relating to such.

D`oh. I`ve not got a fuckin` clue about the CB125 single....



Anyway, this bit.

Tighten carefully until resistance then back off slightly/tighten locknut is
valid for clutch adjustment, but not camchain tensioner surely? All the
tensioners with I`ve come across have all been nipped up nice and tight.

 

Yes, you're right. Wasn't thinking when I posted. All old Honda
tensioners are like that - undo locknut, undo nut, tighten up not,
re-tighten locknut.

The point I'm making is that I did try and tighten it up, but couldn't
feel any resistance.

 

could be that chain is stretched past its max adjustment hence no resistance
when screwing in adjuster,though i believe theres plastic slides which are
the tensioners and these do wear out as i found out on in times past on 250n
and cb100 models....S

 

12k miles from new. Nope.

 

oh...only 12000 miles, i didnt know that,..may i ask of symtoms? ty S

 

Can I suggest you re-read the original posting?

 

I know you said it wouldn't tighten "one way or t'other", but did you
go far enough in "t'other" direction? It was unscrew to tighten on
TL125s, which I believe was the same engine.

 

Krusty fumbled, fiddled and fingered:

Wot he sed ... I had a CB125S and the adjustment screw was anti
clockwise to adjust the tensioner. It pulls the sprung blade upwards,
which causes the blade to push forward in the centre tensioning the
chain. Don't do it too much though cos it's only held on with a circlip.

If you ever need to remove the rotor to get at the aforementioned
circlip, I seem to recall the rear wheel spindle was the required thread
to work as a rotor remover



--
Steve Parry
K100RS SE & F650
and a 520i SE Touring for comfort

(not forgetting the SK90PY)

http://www.gwynfryn.co.uk

 

I put it back exactly as it was before I fiddled with it. Thanks to you
both for the info.

It usually is, believe it or not. Actually, I have a genuine Honda tool
in my toolit...