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Black box silencer - finish??

Posted: Fri Sep 18, 2020 7:34 pm
by SteveS
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Hi
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Received delivery of a second hand black box silencer a couple of days ago, purported to be off a B50SS 1972. On first glance it looked like the black finish had come off in places showing the bare steel beneath but upon closer inspection it looks like the silencer is plated, possibly unpolished chromium?
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Looking over the silencer reminded me of some marks on the silencer fitted to a 1972 B50T I purchased from the US a few weeks ago. Again I thought the paint had worn off leaving bare steel, but now I look at it again it looks like a plated finish.
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Any one else seen this before? My memory is getting worse but I don't remember this detail cropping up before?
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B50SS 1972
B50SS 1972
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B50T 1972
B50T 1972

Re: Black box silencer - finish??

Posted: Fri Sep 18, 2020 9:28 pm
by malcward
Think the finish was black chrome, wasn't much of it left on my 72 silencer, but was still present on the down pipe
Cheers Malc

Re: Black box silencer - finish??

Posted: Fri Sep 18, 2020 11:45 pm
by eebtr7
If the tailpipe curves over to the side, it's from a 1972 model. If the tailpipe is straight, it's from a 1971 model. On my Sept 1972 B50SS, the tailpipe is somewhat smaller than the header pipe. Would this be an effort to quiet the bark? I recall in a road test for the Tri & BSA 650's the 1972 models had a more restrictive muffler to quiet them down, could the same be for the loud mouth B50's?

Re: Black box silencer - finish??

Posted: Sat Sep 19, 2020 8:22 am
by SteveS
Hi Malc

Yes I was aware about the black chrome on the exhaust pipes. :thumb I seem to remember reading that BSA invested a fortune on the plant to carry out the process. It produced a lovely finish which is hard to replicate.

Thanks eebTR7, both the silencers have the curved outlet pipe so are from 72 models :thumb

I believe the top 'coat' on the silencers was a (black) baked on finish of some sort (?) What I had not noted before was that below the black finish there is a plated coating. I don't believe in coincidence; I have two silencers supplied from different sources with the same plated finish. Anyone else seen this before?

Also just noticed there is a drain hole on the underside of the silencer towards the inlet which you can see in the first pic. Don't remember seeing that before either