Exhaust removal/refitting B40 Star

[hoogerbooger]

A couple of novice questions:

1) the front pipe stap attaches to the front engine mounting......Is any support for the engine needed to remove and replace the bolt... to remove/replace the front pipe/ exhaust ?

2) I've previously mentioned my exhaust is very noisy. Rupert Ratio refers to rusting out of internally baffles and increased noise. I'm not sure what these are supposed to look like. What should I see within a non rotted silencer ?
(If I shine a light down the silencer  from it's rear end, what I  see looks like an intact baffle cone( complete no rust or perforations) with constriction to a circular opening of about an inch)
I intend to take the exhaust off, separate pipe and silencer and refit (using loctite 5990) after some other tinkering on the bike.  I'd like it to be quieter and am trying to work out if a new silencer might help....although some have said here the pattern silencers available tend to be noisier than the originals ( My silencer will be 1994 or earlier)   
Advice very welcome

[Rog1]

Could it be a silencer that's supposed to work with an absorption baffle? These have a central pipe surrounded by fibreglass matting or sometimes steel wool. Sound waves vibrate the matting causing friction and so converting the sound energy into heat.

But the matting eventually gets broken up and blown out the back. Replacement matting is available; years ago it was often used on two strokes. Usually there's a fixing screw at the end of the silencer. Once that's out the baffle tube can be pulled out and repacked. The fibreglass can be held on with some wire.

One advantage of this type is that the higher notes are absorbed most, producing a deep but not annoying exhaust sound.

[Greenfield]

Re the front pipe, I think the correct fastening is a bolt through the NS frame and crankcase with a nut and washer holding the exhaust strap. This allows easy exhaust removal without disturbing anything else. Mine has a stud with a nut both sides with the same effect.

[hoogerbooger]

I'll take off the silencer soon so I can look at from both ends. Can then consider/ query further.

So looks like my bolt and nut are back to front. ( pic attached hopefully). I'll find a piece of wood to prop the front of the engine and see if the bolt moves easily.....or not. If not slidey...I may come back on that.

[hoogerbooger]

Well.....bolt came relatively easily....but when reversed doesn't quite align with strap hole.

(Any advice for when I come to refit. If I marry up and it does it again...Do I just file out the hole on the strap)

[Greenfield]

Mine's a '63 and there's no spacer between the bracket and frame. I wasn't aware of changes during production. The bracket is angled inwards from the pipe and I just have a thick washer between bracket and frame to keep it nicely aligned. It'd be worth swapping the bolt around for any future exhaust removal. If the pipe has sprung once the tension was released you could file an odd mm or two to ease it back on as long as there's plenty of metal around the hole.

[hoogerbooger]

I may have found a culprit for excess noise.....but can't be sure. The silencer joint seemed very loose once I'd undone the two frame nuts.....before undoing the join clip nut....but there was a bit of wiggling  of it before the frame nuts were off...so might have been sealing before.

As for the silencer design there are two discs constrictions within the wide part of the silencer.  These are 7cm apart rougly around where the frame fixing bracket is. Each has a circa 1" circular opening at the centre and a small cut out against the outer on one side. There appears nothing between these two plates to absorb sound.....so only baffling would be sound echoing around  between the two plates....and via the small side passages.

No idea if this is an original BSA design....or if extra baffling...sensible to add. Hopefully loctite 5990 on the join and a little at the engine might prove a bit quieter....but I'm not hopeful.

Anyway think I need to do some chrome polishing

[rhyatt]

Don't file anything out, it could cause slight movement and vibration.
The front pipe looks original, many of the replacements have a lug welded on the bend and a separate strap attaching it to the frame.
The baffles look original.
To seal the ingoing exhaust pipe into the head, I've used silicone sealer in the opening and round the pipe.
As it slides into the head, it makes a good joint until carbon builds up around there.
Sometimes, I've had to create a wrap round shim between the silencer and ex pipe to make a tight and clampable fit.
Ensure the slots on the silencer are not already crushed.