Need help with troubleshooting Honda CB125F engine ticking noise

[teodorman]

Good morning/afternoon/evening fellow bikers.

I am having issues with my 16 plate Honda CB125F with 4000 miles on the clock.

A few days ago the engine started making a ticking noise which I am struggling to find the source of.

I have added a video of the noise on YouTube ->

Some of the things I have already checked:

1. I have checked the valve clearances are correct both on the intake(0.08) and exhaust(0.12) valves.

2. I have made sure that the adjuster locknuts are tightened to the correct torque.

3. Plenty of oil which was last changed around 500 miles ago.

Something I want to mention is that on the night before the bike started making the noise last ride back home I heard a loud knocking sound originating from the engine(I think. I had my helmet on so it was pretty hard to determine where it was coming from) by the time I stopped to see where it was coming from it had disappeared and never came back. II made 25 miles back home that night without noticing any serious performance degradation.

Any help will be highly appreciated!

Thank you for reading!

[Snod Blatter]

Is the exhaust still sealed? If you put your thumb over the outlet does the pressure build until the motor dies? A lot of these mystery ticks turn out to be exhaust leaks..

[Guest Richzx6r]

I'd second that, it sounds like exhaust phut where theres a small leak somewhere in the system it doesn't sound terminal

[teodorman]

Thank you very much for replying guys.

I have confirmed that the exhaust is sealed by covering the exhaust hole with my thumb which choked the engine.

[Snod Blatter]

Hmm okay, I think my next step would be to check the condition of the cam lobes and followers - if it has locknuts then I guess this is an old fashioned (i.e. simple and good) rocker arm setup? If so then can you see everything?

It certainly sounds like it's at half engine speed which implies valve train..

[Mississippi Bullfrog]

It does sound like tappets but you say the clearances are on spec. It might be worth checking the faces of the tappets as if they have worn such that they are not flat the measurement you get isn't accurate.

And check you feeler gauge as well. I've seen some so far out that you just won't get anything like close. One even had the metric and inch markings mixed up so the poor guy thought he was measuring in inches but it was actually in millimetres (or vice versa, I can't remember for sure.)

[teodorman]

Hi @Snod Blatter!

I am waiting for the bike to cool off now(left it outside at -2C) after I tested the exhaust for leaks.

I have opened the top engine cover and everything (rocker arms, valve springs, locknuts, cam chain and sprocket) looks absolutely fine. I am thinking that it would be a piston ring but as you say it definitely sounds like the noise is produced at half engine speed which does imply valve issues ...

[Snod Blatter]

How are the rockers oiled? Is it the usual Honda trick of spraying oil from the rocker cover? If so, have you checked none of the holes are blocked?

You sound like you have a good idea of what's going on in there so hopefully we'll manage to get somewhere!

[teodorman]

Hello again [mention]Snod Blatter[/mention] ,

I am not sure how the rocker arms are oiled to be honest with you. I thought it would be by the same oil that is used to lubrications the rest of the engine.

I have attached a few photos of the top end of the engine.

Checked clearances again last night and they are right according to the spec. Also my filler gage looks legitimate as well.

Edited November 19, 2019 by teodorman

[Guest Richzx6r]

Does it have a chain adjuster, auto or manual one? It could be that the chain is being permanently adjusted if it's an automatic one which could possibly make it noisy

[Guest Richzx6r]

Does it have a chain adjuster, auto or manual one? It could be that the chain is being permanently adjusted if it's an automatic one which could possibly make it noisy.

By looking at the last pic, it looks like the rocker arms have little rollers on the inner end are they loose or solid fitting?

[teodorman]

Hi [mention]Richzx6r[/mention] the chain tensioner is automatic but I doubt the sound is coming from the cam chain to be honest with you as it is more of a ticking/knocking sound rather than a constant rattling sound.

I am not too sure what you mean by solid or loose fitting in regards to the rocker arm inner rollers.

[Snod Blatter]

I am not sure how the rocker arms are oiled to be honest with you.

 

Judging by the oil feed in the bottom left corner of this picture (with the rubber ring):

I'm guessing the oil is indeed pumped into the rocker cover and then sprayed down. If you're not too concerned about being poisoned you can try blowing through the corresponding hole in the rocker cover to see if the oilways are clear.

Also do the roller bits that touch the cam lobes still actually roll about? Are they loose at all?

[Guest Richzx6r]

As snod says do the rollers roll freely as it could be that they are not rolling freely and that could be the cause of the noise

[Mississippi Bullfrog]

I should have said earlier - before you starting taking things to bits - an often overlooked diagnostic tool in these days when 'diagnostic' means something expensive and electronic is a good old fashioned stethoscope. A mechanic's stethoscope works the same as a medical one except that it has a metal rod that you place in contact with various parts of the enging. This enables you to hear what is going on inside the engine and makes it very easy to track down noises accurately.

The problem with noises is that they can be transferred because sound travels better through a solid than through air (exactly why the stethoscope works of course). You can replicate the same effect with a large screwdriver, place the handle to your ear and the tip to the engine, but a stethoscope is much easier and safer to use.

[teodorman]

That is a good shout [mention]Mississippi Bullfrog[/mention] !

£6 on Amazon

Will let you know what I find when it arrives.

[fastbob]

Does it have a chain adjuster, auto or manual one? It could be that the chain is being permanently adjusted if it's an automatic one which could possibly make it noisy.

By looking at the last pic, it looks like the rocker arms have little rollers on the inner end are they loose or solid fitting?

 

Yeah , I spotted that . Rollers on the cam followers . I've never seen that before but it's a great idea to even out any wear and reduce friction .

[Steve16]

Hi. I'm having the same issue with the same bike. Did you found out what was wrong with it?

[Fozzie]

Surprised I never saw this, I've rebuilt an engine from one. 

 

A few things I noted as I tore it down and put it back together.

 

The valve clearances go out very quickly, and I once loosened one a tad too much and it made a bit of a racket, but there was still a tick alongside this.

 

The exhaust can be the cause of the tick. When I took the exhaust off, I noticed that the sealing surface was badly corroded. When I put it on there was a pronounced tick and I ignored it, however it soon developed into a death rattle like sound, but only when the engine was hot. A liberal dose of firegum on the exhaust, and it went silent. 

[PaulCa]

What happens if you turn it over slowly with the rocker cover off.  Not enough to get oil pressure and paint the workshop, but maybe a slow drill.  If you can get it to do the tick with the lid open it might reveal something.  I assume you inspected the cam chain and sprockets the whole way around for damage?  The link in the photo which looks different to the others, different colour, is it expected?

[PaulCa]

One thing springs to mind, probably irrelevant, but my Honda CG125 had Honda's secondary air system.  There were gubbins injecting fresh air into the exhaust port and things.