New noise

[Greybeard]

My machine, (Plunger A10) has developed a new noise.  My Davida helmet fits very tight over my ears so it's hard to be sure about the noise; it appears to be from the drive side. It's a kind of rattley grindy sound. The engine still seems the same. The drive chain has been behaving strangely lately; I've been adjusting it and finding it loose again after a ride. Could this noise and chain problem be caused by the gearbox shaft bearing collapsing? I've opened the primary case inspection plug; there are no metal particles in the oil.

[muskrat]

G'day Graybeard.
Have you tried running her on the centerstand. Turn the idle way up, put her in gear (3rd). Now have a good listen. Apply the rear brake a little to load it all up. Does that make any difference to the noise?
Cheers 

[edboy]

hi greybeard, you say after a run the chain is loose and needs readjusting.i ve seen similar problems on triumphs with that plunger chain adjuster design where the bolt thread or chaincase thread are worn and under load the bolt is pushed down and loosens with the chain.

[Greybeard]

G'day Graybeard.
Have you tried running her on the centerstand. Turn the idle way up, put her in gear (3rd). Now have a good listen. Apply the rear brake a little to load it all up. Does that make any difference to the noise?
Cheers

Good idea Musky, I'll try that tomorrow.

[Greybeard]

...that plunger chain adjuster design where the bolt thread or chaincase thread are worn and under load the bolt is pushed down and loosens with the chain.

Sorry if I didn't make it clear; I'm talking about the secondary chain.

[duTch]

 GB, if there is an issue with your gearbox shaft bearing, I can't imagine how you'd have metal from that in the primary, unless as a result of maybe the clutch slapping around a bit of the sleeve gear bush... unlikely to do it suddenly though. ?. ...I had a maybe similar sound a while ago that turned out to be the chain scraping on a bit of the chainguard ....
 Only thing I can think of for the loose chain, is either rapid wear, or maybe have you lost one of the little adjuster screws that push and hold the axle back...?
 (A bit edited)

[Greybeard]

No metal in the primary. Chain adjusters present and correct.

If I get a chance I'm going to start closer inspections today. I'll run her on the centre stand in gear and try to home in on the epicentre of the noise. The sound appears to be from the primary side so I'll take the cover off, although using the filler plug hole I can feel that the primary chain is not too sloppy and the case surfaces are not holding any metal filings.


Much later: Nope; no chance yet! I've been the family chauffeur today.

[Greybeard]

Today the rain stopped and the sun came out; whoopee!
I took the Plunger out for a decent run and I now know what the strange new noise is! The noise is being caused by the innards of the left hand silencer vibrating in sympathy with a certain engine frequency. The noise has no relation to road speed; with the machine on the centre stand it happens on engine over-run after a blip on the throttle.
It's a great relief to realise that I don't have some horrible failure to sort out. 

Anyone got a good method to tighten up silencer baffles, (apart from taking a hammer to the silencer)?

[morris]

Anyone got a good method to tighten up silencer baffles, (apart from taking a hammer to the silencer)?

Emptying a can of PU foam in it...? 

[Joolstacho]

Today the rain stopped and the sun came out; whoopee!
I took the Plunger out for a decent run and I now know what the strange new noise is! The noise is being caused by the innards of the left hand silencer vibrating in sympathy with a certain engine frequency. The noise has no relation to road speed; with the machine on the centre stand it happens on engine over-run after a blip on the throttle.
It's a great relief to realise that I don't have some horrible failure to sort out. 

Anyone got a good method to tighten up silencer baffles, (apart from taking a hammer to the silencer)?

Oooh stick a goldie silencer on it and get THE TWITTER!
(Nooo not tweets!)

[Greybeard]

I have now bought and fitted a new silencer, http://www.feked.com/bsa-a10-gold-flash-650cc-1952-55-silencer.html but have not yet been for a ride.