Author Topic: [1982 Honda CB125s]Camchain tightening procedure - need advice  (Read 622 times)

Offline RoyalRider

  • Posts: 64
  • 2010 Royal Enfield Bullet 500 - 1982 Honda CB125s
Re: [1982 Honda CB125s]Camchain tightening procedure - need advice
« Reply #10 on: Jul 11, 2018, 22:18:43 »
Okay so I am at a loss.

I took off the covers on the alternator side and inspected it and took some photos to show you what I can see. It appears I have the same cam chain tensioner as in the video from my first post.

I did my best to get the light in there:

So I don't know what is up but I once again put a screwdriver down the plug bolt hole and pressed against the mechanism and it would not budge. I then completely removed the adjustment bolt to see what was down the hole and it seems to be some sort of plastic rod/plunger coated in oil. I was able to push down on that one though so I did a few times. I also put the adjustment bolt back in and torqued it loose and tight to see if it affected the cam chain at all and from what I could see nothing happened at all.

I took a screwdriver and pushed on the cam chain to see if it was taut and indeed it is no way shape or form loose and it does move a bit so not over tightened either.

Put it all back together and turned the bike on, let it idle to warm up, attempted to adjust it both ways to see if it affected the sound and nothing happened whatsoever.

I simply retightened it according to torque spec and put the rubber boot back on.

Took it for a rides fine, my original problem that I started this whole process for IS gone which is a relief (stall when stopping for a red light/stop sign from 3rd, 4th, or 5th would cause the bike to stall once stopped. That no longer happens)

But when I got home the bike just reeks of burnt something. Burnt fuel/chemical smell it just don't smell good. It really smells near the exhaust pipe entering the engine so it seems I have some sort of exhaust leak.

In my search for more info to try and determine if this is really a loose cam chain noise or valve out of spec noise I discovered this :

Someone mentioned that sometimes exhausts crack and somehow the inner wall of the exhaust rattles against the outter wall of the exhaust? and that the sound would go away as you reach high rev on the road but as you slow down it starts to chatter again....

I wonder if it could be that? my pipes are 36 years old idk....

But why I don't think it's that is when I am at high rev on a higher gear and clutch in and begin to brake hard the engine makes this super loud winding down noise.....idk if the exhaust rattling would do that sort of noise.

I'm sorry guys I am super stumped....I just have no idea what's wrong and I feel like if I keep ridding my bike is going to grenade despite it riding better than ever and idling better than ever....
« Last Edit: Jul 11, 2018, 22:41:52 by RoyalRider »

Offline TheCoffeeGuy

  • Posts: 644
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Re: [1982 Honda CB125s]Camchain tightening procedure - need advice
« Reply #11 on: Jul 12, 2018, 10:05:49 »
yes that bolt Not your ordinary Blog site.

1968 Harley Aermacchi ML 125 Rapido, restored
1972 Honda Cl 450 engine rebuild, a day rider soon, now sold
1980 Suzuki GS850GL Street Brat  My other day bike
2000 Harley 1200 Sport S My day bike
1982 Honda CB650 Chopper light

Offline RoyalRider

  • Posts: 64
  • 2010 Royal Enfield Bullet 500 - 1982 Honda CB125s
Re: [1982 Honda CB125s]Camchain tightening procedure - need advice
« Reply #12 on: Jul 12, 2018, 10:25:47 »
Hmmm I think you missed my latest reply but yeah it had no effect.

I'm now wondering if I'm crazy and the sound is normal or w/e idk. I went looking on youtube for 1981/82 CB125S idle sounds and some sound very thumpy with a lower speed idle of like 1000-1100 and this one at 1300 or so idle sounds identical to my bike...

Not 81/82 but similar sound :

This one especially sounds similar :

Maybe they just sound this way? Idk my bike runs better than ever so I feel like if the cam chain was loose or if my valves were screwed up the performance would be way down.

I'm thinking maybe since I stage'd 1 my carb and am getting way more power than stock the bike just makes more noise as it is working harder idk.

Going to try and post my idle vid to a cb125s specific forum and see what other owners can say about the sound.

Thanks for all the help.


Found another video of an 81/82 CB125s idling and it sounds very much like my bike so IDK maybe I don't have a problem after all and am going crazy :

« Last Edit: Jul 12, 2018, 12:18:50 by RoyalRider »

Offline RoyalRider

  • Posts: 64
  • 2010 Royal Enfield Bullet 500 - 1982 Honda CB125s
Re: [1982 Honda CB125s]Camchain tightening procedure - need advice
« Reply #13 on: Jul 13, 2018, 12:30:08 »
Okay I think I have the final piece of info I need now.

So we can disregard the videos I posted above re: sound. Most of those bikes are out of spec too.

I contacted someone I knew had a lot of experience with CB125s as he has been selling 125cc bikes in the UK for over 30 years and has personally owned many CB125s. He owns like 12 different motorcycles or something so I trust his judgement.

He told me this :

"First things first - camchain adjustment is entirely manual on these things, and is counter-intuitive. You have to turn the adjuster bolt (on top of the cases, behind the block) anti-clockwise to tighten the chain. I assume you have a workshop manual?

A few years ago, I bought a 'restored' CB125S that was making a noise like yours, cheap, because although it had had a new camchain it was still sounding horrible. I tried adjusting the camchain (see above) and it made no difference, so I reckoned I'd look at the arm that attaches to the tensioner. There's a pivot pin and it's secured in place with a little clip washer.

Sure enough, no clip and the adjuster arm was just dangling, useless. I re-connected it, and fitted a new spring clip (I have a box of the things). One lovely quiet engine.

Check yours. If it's detached, you do have to remove the alternator stator (three bolts, I think) but you can leave the rotor in place: if you have a pair of long needle nosed pliers, there's just enough space to do it."

I find it very interesting that the clymer manual is incorrect. I did some googling and it appears it is also incorrect for the Honda C100 as well.

Now that I have this info I am going to pull the rotor and hopefully repair the chain adjuster.