2023 CB125F-MM Rattle

[Saul]

Ok then brains trust can you help me identify this rattle.     I serviced the bike last week and all went as it should.   Sounded as sweet as it always does.   Any way Shadow came home last night with a rattle after around 300 miles. 
I in paranoia stripped the valve cover and checked  them, they are still spot on but I reset them just the same to be sure.   I was worried one may have back off.   
Anyway after a couple of minutes when the bike comes off fast idle the rattle starts again.  As far as I can tell the cam chain is under tension.   The inside of the head is spotlessly clean as is the oil.  
I was thinking clutch but pulled the lever in makes no difference  

 

Anyway have a listen and see if any of you can make out what it is.   

Shadow denies any abuse and I want to believe her but

[Buckster]

Broken tooth on front sprocket bouncing about? 
 

Stethoscope would help you, I bought one years ago from Machine Mart, saves me a lot of time. It is often hard to pinpoint rattles on a bike as the engine noise masks where the rattles are coming from.

[Saul]

2 minutes ago, Buckster said:

Broken tooth on front sprocket bouncing about? 
 

Stethoscope would help you, I bought one years ago from Machine Mart, saves me a lot of time. It is often hard to pinpoint rattles on a bike as the engine noise masks where the rattles are coming from.

Will have a look for a stethoscope, good plan.  I think it's coming from inside the engine casing but will have a look at the front sprocket nonetheless.  

[boboneleg]

Piece come off of the cam chain tensioner , it wouldn't be the first time it's happened on a Honda

[Saul]

I'm of a bit of a quandary what to do about it really,   I can get a low mileage motor for it on Ebag for £300 to £400 and swap it over in an afternoon. In the condition it is in the bike itself is only worth £1100 to £1500 if  there were no rattle.  Never going to be worth paying anyone to fix it and it would not be done just like that, especially this time of year.  And I can just imagine the grief and pressure I would get from Shadow if she was off the road for any period of time.  While I reckon I could strip and fix whatever it is, it would not be quick and the price of Honda parts is daft.  At a rough glance for a cam chain tensioner assembly is quite spendy.  I have told her to keep riding and let me know if it gets any worse.  

[Buckster]

I would definitely pull the sprocket cover, might be something silly like a stone in there.

[Saul]

Just now, Buckster said:

I would definitely pull the sprocket cover, might be something silly like a stone in there.

I will when she gets back later. 

[Catteeclan]

Place a screwdriver on various parts of the engine and put your ear to the handle.

[Saul]

4 hours ago, Catteeclan said:

Place a screwdriver on various parts of the engine and put your ear to the handle.

I will do that.  I had another good listen earlier when i was repairing the crash damage she did today.  The rattle sounds much worse on the video that it does in the real life.  I think I am going to monitor it for now.    I did clean out the sprocket cover earlier and it was full of greasy shit so now sorted but nothing in their to rattle that I could see.  

[Buckster]

Odds are it is the cam chain tensioner then, have you checked to see if it is tensioning? There is usually some sort of simple test.

[Saul]

7 hours ago, Buckster said:

Odds are it is the cam chain tensioner then, have you checked to see if it is tensioning? There is usually some sort of simple test.

I did when I checked the valve clearances, all looked good

[Buckster]

1 hour ago, Saul said:

I did when I checked the valve clearances, all looked good

If it is a hydraulic tensioner you can usually unload it while the bike is running and then release it to see if it takes up the tension.

[Saul]

58 minutes ago, Buckster said:

If it is a hydraulic tensioner you can usually unload it while the bike is running and then release it to see if it takes up the tension.

Yeah the CBF125 is a weird looking arrangement not like a normal tensioner.

   

[Saul]

21 hours ago, Catteeclan said:

Place a screwdriver on various parts of the engine and put your ear to the handle.

Just been out checking with a screwdriver as you suggest and that rattling is not coming from the engine.  I have tried all over the motor and gearbox and all I hear is mechanical whirring noise as it should be.   No rattles at all in the casing as far as I can tell.  Shadow is off to Truro in a minute but I will strip the panels off later when she gets back and look for something loose, the rattle is sort of metallic so should narrow it down a little.   

[Catteeclan]

3 hours ago, Saul said:

Just been out checking with a screwdriver as you suggest and that rattling is not coming from the engine.  I have tried all over the motor and gearbox and all I hear is mechanical whirring noise as it should be.   No rattles at all in the casing as far as I can tell.  Shadow is off to Truro in a minute but I will strip the panels off later when she gets back and look for something loose, the rattle is sort of metallic so should narrow it down a little.   

Could be the old spot weld come undone in the exhaust. Good hunting.

[Saul]

Just now, Catteeclan said:

Could be the old spot weld come undone in the exhaust. Good hunting.

To be honest as long as it's not anything that leads to mechanical doom I do care that much.  Shadow can get used to the noise.  Tis a tiny air cooled single always gonna have a noisy motor one way or another.   I am pretty relieved it's not coming from the engine casing just the same, thanks for the tip, I don't know why I didn't think of it, I saw my dad doing it often enough back in the day.  I will see if I can source a stethoscope or just buy one from Machine Mart as Buckster suggested.  

[Catteeclan]

When my boy had one it suffered a common fault with the clutch basket drive cog splitting. Was never a prob but drove me nuts to the point I had to replace it.