Honda CG Gearbox Noise

[Nipedley]

Hey guys, a bit of backstory a few months ago my CG started having trouble going from second gear down into first. The mechanic found that a plate and cam had worn inside the clutch cover, and replaced it, which worked great and my gears were nice and smooth again.

Then about 2 weeks ago I noticed a really strange noise while at high speed.

I've investigated it a lot, and this noise is coming from the front end. It gets worse if you pull in the clutch (i.e. louder) it sounds like static at high speed, warbling at 20-30mph and at low speed it sounds like somethings winding, and the winding slows as the bike slows.

This noise *ONLY* starts if I go over 60mph. I can sit at 50mph all day, if I notch over 60 it will start and keep going until I stop for a while.

Does anybody have any ideas? I'm guessing this is going to be an expensive gearbox jobbie.

Thanks for any thoughts

[The Artist]

Sounds like crank bearings or something similar. Could be anything on that side of the engine, maybe the clutch. When you say plate and cam, can you elaborate?

[Nipedley]

I'm afraid not, the furthest my mechanical knowledge goes is oil change and chain tension.. He said it was related to the gear selector, and because it was worn it wasn't operating correctly and thats why it had trouble between 1st and 2nd gears.

The engine has done 16400 miles, and is 5 years old. Regular oil changes, not much else has needed to be done except those bits being put in a few months ago. I'm 99% sure it must be a related issue, as only after those parts were replaced did this noise come about, and the 1st -> 2nd gear is still slightly iffy even with the new parts.

My feeling is the worn parts inside the clutch cover "plate and cam" were worn by something wrong deeper inside the gearbox, which is why it still has small hiccups now and then. Of course I have no mechanical knowledge to back that up, but having observed this over the past 5 months thats what it feels like. I can live with the gear hiccups but the noise is seriously unnerving, as it is very loud and does not sound at all good. But only over 60mph

[Vincent]

It's bit hard to diagnose from what you say but my first impressio is that it might be something loose vibrating - might not be too serious. What is "winding"

[Vincent]

[Nipedley]

Hmmm well at high speed it sounds like the static you get off a snowy white channel on an old analogue television. At 30 - 40 it sounds kind of like warbling on/off as my brake pads did when they were glazed. And the low speed (sub 20mph) winding sound, like somethings spinning really really fast/loudly.

It's a very distinctive and loud noise, I will try and record it, but it's a spinning sound, and the spinning seems to slow equally as the bike does. It's definitely not back wheel or drive chain/sprockets as I've had that overhauled since this has been happening. Definitely coming from the front, and the winding/spinning noise gets louder if I pull in the clutch regardless of actual speed.

The only mechanism I can imagine that would produce a similar sound is say a hand crank on a portable torch or radio, wind it really fast and you get that spinning noise it's very similar

[The Artist]

Well if it gets louder when you pull the clutch in and the revs don't change that narrows it down to the clutch. 99% sure that is the part that is the problem.

[Nipedley]

Thanks for the info, I will try and get a decent quality recording of the whole thing tomorrow. Gives me an excuse to try out my camcorder again if nothing else

[Nipedley]

Ok guys, my DVR battery was dead so I had to get a new one. Here's the video;

https://www.youtube.com/watch?v=iDNImLrpWhg

My bike is almost silent on the microphone when running right, so apart from the wind noise, any other noise on the vid is from the problem I'm trying to diagnose.

It doesn't come up brilliant on the microphone but you can definitely hear it well. On the first clip you can hear that the noise disappears when I slow down to a stop, when on the second it gets worse when I am slowing to a stop. It's especially audible at low speed but also very much audible at 60mph. It's also sporadic in nature and only starts when you've been doing high speed for 5+ minutes.

Any suggestions very much appreciated

P.S. Apologies for the skewed camera!

[The Artist]

TBH that could be anything. Without someone who knows what to listen for to be there in real life, there isn't much help we can give.

If you can confirm this for me.

Does the noise appear when you pull the clutch in and the revs do not change or does it appear when you pull the clutch in and the revs change?

[Nipedley]

The noise is there whether I pull the clutch in or leave it out, and also whether I rev it or not

It does seem to get slightly worse if I pull the clutch in while it's making the noise, but only slightly.

[bike2626]

Did you discover what the problem was?

[Nipedley]

It's going in to the garage tomorrow to hopefully find out.

Whatever it is it mustn't be anything too critical, as I've done probably 1000 miles with it like this now.

After living with it for a while, I've noticed certain things. The specifics of the noise changes depending on gear -

in 4th + 5th gear the noise appears when it feels like it.
in 3rd gear it only starts if you roll off the throttle, as soon as you put the throttle on a bit the noise goes
in 2nd gear there is no noise at all
and in 1st gear the noise only appears with the clutch in. however when starting off from a stop, you will hear the noise 'spin up' before it catches and goes away with the clutch out.

And of course this only happens if you go over 50mph for a while to begin with, you can ride under 50mph all day with no problems.

I've observed this over the past several weeks and confirmed it. Very weird.

[stonesie]

The good news is that from what you have said and that video it is 99% drive train related, not the engine/crank.

I'm suspecting the clutch itself, maybe slipping or something has found it's way in there that shouldn't.

Matt.

[Nipedley]

That's interesting, a few people have mentioned it might be clutch related.

I had other work done today; general service, clutch cable, fork oil seals. My mechanic then took it on a route that I *know* causes the noise to appear and he said he heard nothing, I showed him the video and he said he'd never heard anything it before.

The difference in the clutch lever is absolutely astounding, maybe my clutch has been incorrect for several thousands of miles. I'll test it for a while and see!

[ThoughtContro...]

Sounds a bit like the clutch/gearbox/front end noise problem I've got with my CBR125. It's intermittent, it only shows up on NSLs/ motorways when you're doing 60-70 and 9,000rpm or so for a while. I thought it only showed when I used 6th gear (you can only hear it properly when you've changed down after slowing down), but it showed up the other day and I'd pretty much swear I didn't go beyond 5th.

Sounds similar to yours from your youtube video (tho I know what I'm listening for) sort of similar to this, when he presses the pedal in, except no where near as extreme.

https://www.youtube.com/watch?v=pQo-U3VNzdc

You really need a good windshield with a good quality mic to record it properly.

I can commute up to 50 or so all week long and it's sweet. Cane it trying to keep up on the motorway and it comes back sometimes. I can only hear it properly when I slow down and change down to 4th or third. Like yours, gets noisier if you clutch in. Usually disappears if you change down to 1st.

A pain in the bum as its otherwise quite a sweet bike.
____________________
Prize cunt
--
"In a world of universal deceit telling the truth is a revolutionary act" - George Orwell

[Nipedley]

Yep, that's very similar.. Just not quite that bad. At least I know I'm not the only one! It's gotta be something to do with the clutch. If I knew what exactly, I'd get it done. Now I'm kind of hoping with the adjustments from today I might be able to forget about this problem for a few thousand miles at least.

[crackpotterpi...]

I would of said a clutch related issue,maybe a bolt come loose on the basket itself?
____________________
1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[ThoughtContro...]

The youtube video I linked to above said the throwout bearing resulted in that noise. That equates to the lifter plate bearing (part 19 in this parts diagram)

I've got a clutch nut tool on order, so as soon as it comes I'll get to check the bearing and clutch out properly.

In my other thread someone suggested that freeplay might be causing the noise. I checked it and there was not enough, so adjusted it. The noise still occurs under the same circumstances, but I'm guessing that if the freeplay was out over a long time that may may result in undue strain on the lifter bearing and clutch plates. Riding the bike near its top speed its going to wear alot more, get hot and start making a noise.

In my case when going slow the noise isnt there as the bearing is under less stress and its cooled down. As the bearing gets worn the noise will occur at lower speeds until its fails completely. That's my current guess anyway. Please feel free to correct my hypothesis if it appears delusional. Spent most of yesterday reading what I can about clutch operation and watching youtube videos on how to change the plates.

I'll find out when the castle socket arrives and I get the chance to poke around.
____________________
Prize cunt
--
"In a world of universal deceit telling the truth is a revolutionary act" - George Orwell

[stonesie]

It sounds very possible that the clutch cable being tight would cause that, like driving a manual car using the clutch as a foot rest will knacker the release bearing


I hope it is something that simple and easy to fix

[Nipedley]

Well, it's still doing it - nobody seems to know what it could be including the mechanic, and she's still riding beautifully several months and probably a thousand miles since this noise started. I'm just going to take the mechanics advice and tune it out until something explodes, at least then I'll know what the noise was!

[radical]

Op, you sure you dont have a leak around you exhaust manifold ? check his by blocking the exhaust pipe by holding a rag over the exil pipe and revving the bike to see and hear if any gases are escaping from the joint between the cylinder head and the exhaust pipe.

[ThoughtContro...]

I think I've still got my noise.

Changed the lifter plate bearing the other week, and did the clutch springs too. Did a half circuit of the M60 to Trafford Park and there's still some noise. That kicks out the theory that it was the Lifter plate/Release bearing.

Here's an attached side shot of the old bearing

One thing tho, if you look at that pic theres a over-polished part to the outer case of the bearing. This is the bit that sits in the lifter plate. When everything is cold its a snug tight fit. If you take everything apart after the engine has been hot then the bearing comes out easy peasy, not overly loose, but not tight either.

I presume in operation that the outer bearing casing is supposed to remain tight in the lifter plate and whizz around with the clutch. The inner part of the bearing is in contact with the lifter "top hat" piece, which should keep the from rotating. The bearing does what it does and keeps the fixed inner and fast rotating outer casings smoothly doing their job.

So if so, then why the polished part? If the outer casing is fixed in the lifter plate which is bolted to the clutch body, then there should be nothing to polish it? It's fixed so there's no movement, that's what the central bearings are for, right?

Is it possible that as things get hot after 9,000rpm for a while, that the outer bearing casing becomes a bit loose in its seating in the lifter plate and is rotating against the lifter plate and is the thing that is making the noise? Or am I guessing total illogical crap? I really don't want to have to split the crankcase and replace any bearings there, especially as I don't know if any of them are the problem, or if they are which one it is!

I can commute all month and never notice a thing, cane it for half an hour on a motorway or NSL and, "Houston, we have a problem".

I'm stuck with either a ride it until the noise becomes apparant all the time, then either fix it or replace the engine OR sell the bike, in which case some other poor tw@ gets lumbered with the problem.
____________________
Prize cunt
--
"In a world of universal deceit telling the truth is a revolutionary act" - George Orwell

[Nipedley]

It's still there, though I've pretty much tuned it out now. Definitely not the exhaust but thanks for the suggestion. I got another mechanic to take a quick look at it today on a test ride and he heard it clear as day but still no clear idea on what it might be. I think the plan is to wait until it gets a bit worse and then the noise might be more identifiable.

On a side note, one of my brake pads sheared off today. That was a bugger!

[stonesie]

Sorry to drag this back up but mine is also making a similar noise when it is fully warmed up, like yours it is totally silent in 2nd gear.


I am pretty sure I have the cause sussed...

https://www.hondaoriginalparts.com/hpl/images_large/13KCHRB1/imge/E__1000.jpg

6 = 2nd input
7 = 2nd output
13 = 5th input
14 = 5th output

8 = Prime Suspect = £4.82 from Lings Honda

It is something rubbing or chattering inside the gearbox and does not happen in 2nd.

From the diagram both parts of 2nd gear are constantly turning, on the lay shaft (output shaft) it is free spinning on a bush unless locked to the shaft by the dogs on the 5th gear sprocket.
So only when that 2nd gear output sprocket is locked does it fall silent.

My money is on the bush being worn out of spec


Its a £5 part, but man, what a ball-ache to get to it