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Ayrton
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PostPosted: 22:42 - 25 Nov 2019    Post subject: Engine rattle Reply with quote

So my brothers CBR125 started making a rattling noise after we went out on a 100 mile ride a few weeks back and I cant figure out what it is.
We have checked the valve clearances and they are all ok and we also replaced the cam chain tensioner as I read those are common faults but it's still there. It sounds like the noise is coming from the top of the engine.

One thing to mention is after we checked the valves I checked the oil and it wasn't even full enough to be shown on the dip stick. We did lose a little bit of oil when I didn't realise the rocker cover wasn't seated fully and started the bike for a second, but not a massive amount came out. He's insisting he checked the oil recently though Laughing

Anyone have any idea what could be the problem?
I've read here https://www.bikechatforums.com/viewtopic.php?t=306188 that the cam bearing tends to be an issue. Is that something I could check without removing it?

heres a video (ignore the smoke, some oil got on the exhaust):
https://vimeo.com/user105573558/review/375470013/7b09ca02c1
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stevo as b4
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PostPosted: 23:41 - 25 Nov 2019    Post subject: Reply with quote

If you or someone else has run the bike low enough on oil for it to barely even touch the dipstick, then well you've already fucked that engine and you better look for a replacement lump, as it's not going to rattle for much longer.

Give yourself a kicking and get your wallet out.
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Ayrton
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PostPosted: 00:08 - 26 Nov 2019    Post subject: Reply with quote

mpd72 wrote:
Could be all sorts if ran low on oil. Usually expensive such as big end, small end or crank bearings.

Drain the oil and look for metal particles.


Did that and couldn't see anything in the oil.
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A100man
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PostPosted: 00:11 - 26 Nov 2019    Post subject: Reply with quote

Low oil, hundred mile ride, rattly engine hmm. I suppose it could be connected..
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Shaft
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PostPosted: 00:15 - 26 Nov 2019    Post subject: Reply with quote

Shame your Vimeo link doesn't work for me, you can get a good idea of what's going on from the sound.

Lighter tinkling/tapping/grating sounds tend to come from the top end, bottom end noises are usually deeper and lean towards rumbling or knocking.

Cam and primary chains make a variety of noises.
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Ayrton
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PostPosted: 00:39 - 26 Nov 2019    Post subject: Reply with quote

Strange it seems to be removed, try this https://streamable.com/9i95a

I understand it's almost definitely related to the oil, I'm just wondering if it's possible to track it down to something that could be easily changed like the camshaft.
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Sister Sledge
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PostPosted: 08:43 - 26 Nov 2019    Post subject: Reply with quote

Firstly, if oil was lacking on that run then if damage is at a camshaft then it's everywhere. Low oil damage is throughout - wherever that oil was fed to within the engine will have damage. If oil didn't matter for say gears or crankshaft then manufacturers would send oil to them.

The sound. Firstly is the exhaust leaking at the head?
If the exhaust is sealing then the sound - it's at the same time and with every single rotation of the engine - that means crankshaft, connecting rod and piston assembly. Factor in too whatever they touch as they move.
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Ayrton
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PostPosted: 11:26 - 26 Nov 2019    Post subject: Reply with quote

Thanks I thought that would be the case. I remember him having problems with the exhaust not sealing before so I'll double check that.

Also I just realized he checked the oil when it was on the paddock stand, so I guess this could tilt the bike enough to give a false reading? I'll give this a test later to see how much it matters.
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Pete.
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PostPosted: 12:29 - 26 Nov 2019    Post subject: Reply with quote

Check the exhaust where it bolts to the head. Could just be that it'd loose or blowing.
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bikenut
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PostPosted: 12:42 - 26 Nov 2019    Post subject: knock Reply with quote

Yep sounds expensive......but check the exhaust for a leak and hope......

Remove the plug and look at the piston crown, is there a shiny ring on the crown ?

Check crank and piston movement, are they "in step" or does the crank move ( big end "play" ) with no piston movement at say half stroke??

Check cam area for loss of lub/blueing, and check rocker arm contact pads for camshaft. The cam is on roller bearings....


https://images.cmsnl.com/img/partslists/honda-cbr125r-2004-4-england-crank-shaftpiston_mediumecpp4e1e__1500_6138.jpg

This may not be your exact bike so check..........balance system something to consider/worry about......
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redeem ouzzer
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PostPosted: 13:07 - 26 Nov 2019    Post subject: Re: knock Reply with quote

bikenut wrote:
Yep sounds expensive......but check the exhaust for a leak and hope......

Remove the plug and look at the piston crown, is there a shiny ring on the crown ?

Check crank and piston movement, are they "in step" or does the crank move ( big end "play" ) with no piston movement at say half stroke??

Check cam area for loss of lub/blueing, and check rocker arm contact pads for camshaft. The cam is on roller bearings....


https://images.cmsnl.com/img/partslists/honda-cbr125r-2004-4-england-crank-shaftpiston_mediumecpp4e1e__1500_6138.jpg

This may not be your exact bike so check..........balance system something to consider/worry about......


I really am going to start downrating every single post where you mention CMSNL....
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Polarbear
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PostPosted: 13:56 - 26 Nov 2019    Post subject: Reply with quote

That sounds like an exhaust leak to me. Not 'tinny' enough for a top end rattle or 'bangy' enough for the big ends. (good marine engineering terms them Laughing )

However diagnosis by computer is rather hit and miss and what can be obvious when you are present isn't over a video.

If it isn't an exhaust leak, it's going to be expensive. A rebuild or new engine I would guess.
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stevo as b4
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PostPosted: 19:16 - 26 Nov 2019    Post subject: Reply with quote

Drain the oil and see what's in it bits wise? But more importantly see how much comes out. The average 125cc engine will hold 1litre of oil give or take a couple of 100ml. If all you get out of it is a cup full or less, then I'd unbolt the engine to remove it from the frame, and then chuck it into a skip.

When are 125cc daily riders going to understand that these small hard worked engines with small oil capacity, are going to use some oil, and that they don't have much oil in them to start with, to allow this to happen without catastrophe?

If you do 500miles a week that should be at least oil level checks and lre-ride top ups as they are required.
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Ayrton
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PostPosted: 20:40 - 26 Nov 2019    Post subject: Reply with quote

Unfortunately he drained it into a pan that already had some oil in it so I'm not sure how much came out.
I'm not convinced now that it had low oil though. I just tested the difference between measuring it on the paddock stand (how I measured it earlier) and on the ground and the level drops about half. Given that it also spurted out some when the valve cover was loose it could have been within the correct level when he was riding and we just measure it incorrectly.
Not saying it was as he definitely doesn't check it too often, just an idea Laughing Just want to

We just went and checked the exhaust and it is quite tight and I cant see/ feel anything coming out. He did make his own bracket for the head mount though as the old one was thin so I thought it may have caused an issue. I've got a new gasket here for it so I'll give that a god when I get some more time.

Also another recent development Laughing when testing it again it ran out of fuel and shut off. Is there any way that could be causing it?
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MCN
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PostPosted: 22:06 - 26 Nov 2019    Post subject: Reply with quote

Is there an oil filter or screen?
Jewellery usually gets blocked by the filter
/screen (If fitted).
Whip it off/out.
Cut the filter open and spread the paper/fabric out and look for metal. If there's metal then the engine is dusted.
Wash the screen in petrol/thinners in a container and pour out the petrol and look for metal. (Like panning for precious metals)
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Shaft
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PostPosted: 23:54 - 26 Nov 2019    Post subject: Reply with quote

Polarbear wrote:
That sounds like an exhaust leak to me. Not 'tinny' enough for a top end rattle or 'bangy' enough for the big ends. (good marine engineering terms them Laughing )

However diagnosis by computer is rather hit and miss and what can be obvious when you are present isn't over a video.

If it isn't an exhaust leak, it's going to be expensive. A rebuild or new engine I would guess.


I agree, that's either an exhaust blow, or something absolutely catastrophic.

Doesn't sound like the sort of metal on metal action you get with oil starvation, unless bearings have shit themselves at both ends of the motor, but then I wouldn't expect it to rev quite so happily.

Stranger things have happened though.
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Ayrton
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PostPosted: 00:25 - 27 Nov 2019    Post subject: Reply with quote

It has an oil screen so I'll check that.

It sounds a bit more metallic in person I think, but it's hard to tell. Here's another video if it helps https://streamable.com/2iisn
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steve the grease
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PostPosted: 00:37 - 27 Nov 2019    Post subject: Reply with quote

Ayrton wrote:
It has an oil screen so I'll check that.

It sounds a bit more metallic in person I think, but it's hard to tell. Here's another video if it helps https://streamable.com/2iisn


Sounds very cam followery to me, whip the lid off and check it out.

On the first clip the exhaust can be heard blowing too.
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Ayrton
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PostPosted: 00:51 - 27 Nov 2019    Post subject: Reply with quote

steve the grease wrote:
Ayrton wrote:
It has an oil screen so I'll check that.

It sounds a bit more metallic in person I think, but it's hard to tell. Here's another video if it helps https://streamable.com/2iisn


Sounds very cam followery to me, whip the lid off and check it out.


Thanks, how can I check it's all in good shape? I've had the cover off a couple of times, but I'm not too sure how to check anything beyond the valve gaps.
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Pete.
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PostPosted: 01:27 - 27 Nov 2019    Post subject: Reply with quote

Ayrton wrote:

Thanks, how can I check it's all in good shape? I've had the cover off a couple of times, but I'm not too sure how to check anything beyond the valve gaps.


If it's been oil starved then the followers will be faceted instead of smooth. When you get the top off take a very close look att he face of the follower that runs against the cam lobe. It should be a smooth, even curve. If the face has flats like the outside of a 50p (or even worse) then they are scrap.
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Sister Sledge
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PostPosted: 07:56 - 27 Nov 2019    Post subject: Reply with quote

Back to the beginning:
Replaced the cam chain tensioner - what with? New unit, used unit or manual adjusting nut/bolt type? Did it make any difference at the time?
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Ayrton
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PostPosted: 10:03 - 27 Nov 2019    Post subject: Reply with quote

Sister Sledge wrote:
Back to the beginning:
Replaced the cam chain tensioner - what with? New unit, used unit or manual adjusting nut/bolt type? Did it make any difference at the time?

New aftermarket auto adjusting unit. Didn't make any difference at all.
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stevo as b4
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PostPosted: 11:40 - 27 Nov 2019    Post subject: Reply with quote

As said cut open the filter or remove the gauze screen or strainer and look for metal bits.

Does your brother need to use this bike as regular transport?

If so I'd be looking around for a used CBR engine from a low miles bike. There must be lots of them out there, but avoid ebay sellers unless you're going to look at the engine in person yourself before bidding/buying.

That way you can get back on the road quickly, and you've got the option of either stripping and re-building the original motor as a future project, or just taking it to weigh in for scrap. In fact you might want to keep the original engine in the shed, incase you sell the bike on in the future, and the buyer wants to re-instate the matching motor themselves.
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bikenut
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PostPosted: 15:02 - 27 Nov 2019    Post subject: noise Reply with quote

I really am going to start downrating every single post where you mention CMSNL....

That ok, but the exploded views will show people whats in the engine etc., like a filter screen, centrifugal oil filter, balance system etc. etc. etc..

Do other people find cmsnl ( thats done it !! ) usefull??????

Maybe a pole should be conducted about that?

Any big end play found as per method suggested and any bright "ring" on the piston crown as if the piston has been hitting the head?
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