CB125T cam chain adjuster

[bobjohnson]

So ive got a little chatter coming from the head of my bike, I thought it was the valves at first cus the maintenance is every 2000km or so, so i re-did those, "adjusted" the cam chain tensioner (untightened and retightened the bolt) but it still makes a chatter at idle. Does anyone know how this cam chain adjuster actual works? The manual says just put the engine at the T1 mark and loosen the nut, and it adjusts automatically. Should i be seeing any movement or hearing any clicking noises like i do with my 450? The adjuster stud is just kinda hanging out in there when i take the nut off, i can pull it backwards but it doesnt go forward at all really. When i tighten down the nut on it, it obviously slides out but the manual only make reference to making sure it doesnt twist (it doesnt, either way) and not to push it in at all. I tried spinning the engine over by hand while it was loose but the adjuster stud didnt move at all.


The bike is basically the same design, engine wise, as the 70s CB125 singles, but with in a twin configuration. Maybe its normal for it to be that chattery? It runs fine and off idle you cant hear any chatter so im pretty sure its not the valves.

 

[crazypj]

It's more likely you set valves on overlap, real common problem.
Adjust cam chain when you have valve cover of, you should be able to feel it 'drop'

 

[bobjohnson]

I dont feel like i could have set the valves on overlap, i checked to make sure the rocker arms were loose before i set them (same way i set them every other time). Would that be possible even if the rocker arm was loose? Would the bike even run properly if that was the case?

 

[crazypj]

Whatever, you did it right, you work it out

 

[bobjohnson]

I was actually asking for more help. Im not clear on that part. I was under the impression that if the rocker arms are loose, you can set the valves then as thats what ive been told, and that if you accidentally set valves on overlap then the bike doesnt run. If its possible to set them on overlap and the only symptom is chatter, if you have any tips on how to avoid that, id be really grateful because i dont know how to tell otherwise.

 

[crazypj]

watch an intake valve, it goes down on intake stroke and comes back up. then you find compression TDC and set tappets on that cylinder.
it's not only possible to set on overlap, it's very common.
Adjust tensioner while you have cover off, I never found an easier way of doing it.
Do you have the duplex chain or the Hy-Vo?

 

[bobjohnson]

Neither, its a single chain, like a tiny drive chain.

 

[crazypj]

I thought you were asking about a CB125 T which should be a twin cylinder.

OK twin is NOTHING like 1970's singles

 

[bobjohnson]

It is a twin, but its only got a single chain. I was told that other than the top end and the crank shaft it was very similar to the singles of the same era (early 80s). I could be wrong as theres not a lot of information on the bike, it was never sold in north america as far as im aware and ive never owned a 125 single. All the information I have on it comes either from old guys who "used to own one" back in europe, or the garbage haynes manual i have for it.

 

[crazypj]

The Haynes manual is actually pretty good from what I remember.
I'm having some major issues with ISP, start a message and system keeps crashing.
Had to call company and re-boot modem after removing battery, I'm posting bits without them making sense hal the time

 

[crazypj]

I've done a lot of work on them, worked in a Honda dealers when they were new.
Setting valves is easy enough, I already gave you all the info you need.
Never seen one with single row chain though?
Cam chain tensioner (about 5th attempt to post)
It's closer to the type in a CB550, bolt slides in a channel,, thats why you cant push it in and when you pull out your moving the entire mechanism.
Spring pulls tensioner down, usual cause of them not working is stupid 'damper' Honda fitted to everything. (why I worked on so many of the V-4's and hate the damn things)
It's a rubber tube over the spring, and it's too long.
That may not be your problem but I would pull cover and push tensioner down by hand to check (it's only two bolts in cover and one to remove tank)

 

[bobjohnson]

Sweet, ill check that out, thanks very much PJ.