Intermittent noise when riding, could it be my chain?

[Craizeehair]

I took the bike down to the Ace Cafe the other week and noticed a noise coming from the bike, if I had to describe it I would say it sounded like a chain or belt catching, rubbing, chafing?

It’s not constant, it comes and goes and it does seem to keep time with the momentum of the bike moving and doesn’t do it when stationary.

I’ve pulled the chain guard off and there are marks there that to me, look like the chain could have been catching, not serious gouges but definitely marks, not the easiest to catch on the phone camera.

I also removed the rear crank case cover and there is definite wear marks, is this normal, I presume (probably wrongly) that is quite normal, hence the rubber?

Are there any issues known or things I should be looking at and checking. I’m not sure the noise is the chain, so I’m open to suggestions, I realise it’s hard, if not nearly impossible to fault find blind or ver the internet but if anyone has suggestions as to what it could be or anything with checking I would be grateful.

There is about 15-20mm play on the chain.

[K2-K6]

Fairly normal to have those mark in the rubber, as you note, it's there to stop it rattling on the aluminium.

A thought though. Have you checked chain slack at multiple points ? If its uneven (sometimes when contemporary you'd get a chain that was significantly different in dimension along different parts) to make it flap up and down, hitting the guard variously.

Worthwhile checking to see if there's any inconsistency present.

[Craizeehair]

Thanks for the reply, if it is inconsistent then I presume that’s a new chain?

[K2-K6]

If you find anything significant, then also include rear sprocket for concentricity to eliminate that part.

Sometimes you can here quite clearly when someone pulls away from a bike meet or similar a pulsing noise as they rotate the wheel.

If the chain is definitely bad, then not much option but to replace.

If it did in any way appear to be corrosion linked (chain pins etc) then trying a EP gear oil application could be effective. GL5 rated is very good on chains and has not much smell like older oils of this type are characteristic in pong.

Hopefully detailed inspection will confirm if there's anything to be acted apon.

[Craizeehair]

I checked the chain and it was 15-20mm in places and very tight, maybe 5-10mm in others. I slackened it right off and started again. It’s now pretty much 20mm, not exact everywhere maybe 15mm in places?

I took the bike out today without the front sprocket cover or chain guard, I did just over 60 miles and didn’t hear a peep so I’m hopeful it is that.

My question now is, if I put the cover and chain guard back on and it starts again, what would be next steps… New chain and sprockets?

[Bryanj]

New chai definately, sprockets maybe depending on tooth wear

[Craizeehair]

Thanks Bryan, I’ll see what happens when I get it put back and ridden again. If I do the chain, I will probably do the sprockets for peace of mind.

The difference in the slack before I readjusted the chain and after, is there any logical explanation for that? There is definitely less variance and more uniform now for sure??? Could poor alignment do that?

[Bryanj]

Possibly but more likely tight pivot pins in the links, chains do not like standing still doing nothing, try motorcycle products.co.uk but look through all the pages for your model as similar things at different prices on different pages

[K2-K6]

Thanks Bryan, I’ll see what happens when I get it put back and ridden again. If I do the chain, I will probably do the sprockets for peace of mind.

The difference in the slack before I readjusted the chain and after, is there any logical explanation for that? There is definitely less variance and more uniform now for sure??? Could poor alignment do that?

[/b]

Certainly odd that you've got a variable as the error would usually stay the same.

As a check though, put your fingers in behind the frame at left swingarm pivot, now squeeze one of the chain runs (top or bottom) to the arm itself. You'll be checking for movement in swingarm bushes when the chain loads and unloads tension.
Any shift there with arm bushes, and it'll give you problems.

For variation in chain like this (never taken one apart to look at links) comes down to some level of corrosion / wear along the run.

Suggestion to use GL5 oil initially will give results usually in this scenario. It will penetrate the links to the pins etc and highly effective in taking chain load. It's a low cost way to verify those links etc.

Failing that, definitely into chain replacement to deal with it.

[Craizeehair]

Thank you, I will take a look, all new bushes so hopefully ok there. I’m thinking chain and sprockets to put my mind at rest.

[McCabe-Thiele (Ted)]

Not sure if this helps - I had an issue on my Suzuki 750 that was quite odd to me - there was a medium speed thrumming sensation that came and went. It turned out to be the chain had stretched in places. I replaced the chain & spockets it rode perfectly after that.

[Craizeehair]

Thanks, pretty sure it’s a chain and sprockets change for me and see from there. Appreciate all the replies.

[flatfour]

I had something similar on my CB750 K6 a few years ago.

It turned out to be the final drive chain, where the original had been replaced with an "O" ring type and, being wider it was touching the engine case at times, presumably depending upon its exact position on the front sprocket as it rotated.

A replacement standard chain sorted things out.