Author Topic: B31 & small BSA bikes  (Read 3003 times)

Offline Bikergrandad

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B31 & small BSA bikes
« on: 13.10. 2014 19:57 »
 Hi to all.
 Muskrat I have had two A7 Combination but that was 40 yeays ago.
   Thank you for letting us have a site for B31 and smaller BSA bikes.
    So send in your photos of our bike or bikes and a write up.
    I just sold my BSA C12 1957, but this is my bike now B31 1954, it needs some work on it.
    Magneto Rewound, Seals, a lot of the bike will be sprayed and a Complete Service.
    Thank you BOB.
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Too Old To Die Young.
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Offline muskrat

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Re: B31 & small BSA bikes
« Reply #1 on: 13.10. 2014 20:08 »
G'day Bob, nice work mate.
A lot of the cycle and electrical parts on the B's are the same as A's.
I love the sound of a single. I heard one go past a few weeks ago. I heard him wind all the way down to the lake a good 3 miles and could tell which bend or dip he was at by the tone.
Cheers
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Online Greybeard

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Re: B31 & small BSA bikes
« Reply #2 on: 13.10. 2014 22:30 »
I love the sound of a single.
Yes, me too. If I were to consider selling my A10 I would like a good old single cylinder plodder. I think a single would suit my riding style these days.
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Offline scotty

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Re: B31 & small BSA bikes
« Reply #3 on: 14.10. 2014 00:07 »
here's my '54 B33 single

great fun to ride

S

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Scotty

Current liabilities:
'56 A10 Red Flash
'54 B33
'98 HD FLHTPI
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Offline muskrat

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Re: B31 & small BSA bikes
« Reply #4 on: 14.10. 2014 01:48 »
Good one. Looks like someone tried to ride a HD over the bridge!!
Cheers
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Brian

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Re: B31 & small BSA bikes
« Reply #5 on: 14.10. 2014 01:56 »
Nice one Scotty. Here's a pic of my '55 B33.

Also my '47 B31 and '49 plunger B33.

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Offline muskrat

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Re: B31 & small BSA bikes
« Reply #6 on: 14.10. 2014 02:26 »
I'VE CREATED A MONSTER *eek*
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Brian

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Re: B31 & small BSA bikes
« Reply #7 on: 14.10. 2014 02:45 »
Best not mention the M series then.   *conf*
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Offline Topdad

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Re: B31 & small BSA bikes
« Reply #8 on: 14.10. 2014 11:24 »
Really nice pictures , yeah could live with a 500 single ... if I didn't have a A10 , BobH
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Offline Beezageezauk

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Re: B31 & small BSA bikes
« Reply #9 on: 14.10. 2014 18:56 »
I share my riding between my A10's and my faithful B31.

Owned since 1974 the old girl has taken me to almost every country in Western Europe and until about 10 years ago she was often seen two up with full camping equipment.  "The Cup", as she is affectionately known, is still used regularly for long distance trips and isn't that much slower than the A10 Golden Flash.  In comparison she's lacking a bit in acceleration but considering that it's only just over half the engine capacity it does pretty damn good.




Beezageezauk
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Online KiwiGF

  • Last had an A10 in 1976, in 2011 it was time for my 2nd one. It was the project from HELL (but I learned a lot....)
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Re: B31 & small BSA bikes
« Reply #10 on: 15.10. 2014 07:27 »
this is my b31, it will end up as a rigid special with 390cc, yamaha piston,  389 carb and goldie touring cams

Ive ridden my a10  a fair bit in the company of a plunger b31 with similar engine spec and the b31 keeps up easily (dammit)  *wink2*
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New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline wilko

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Re: B31 & small BSA bikes
« Reply #11 on: 15.10. 2014 23:05 »
Why a Yamaha piston. The usual overbore is with a T140 piston which are cheap as chips on ebay a pair? If you seize one you have a spare, all for 150 bucks!
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Online KiwiGF

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Re: B31 & small BSA bikes
« Reply #12 on: 16.10. 2014 05:19 »
hi wilko, the project bike came with the xs650 piston and the cylinder has already been bored to match, its been looked at by a local "expert" and there are pros and cons, the yamaha piston is lighter with a shorter skirt and has nice narrow rings, but it has valve cut outs in the wrong place, it looks like it wont need a spacer under the barrel to reduce the compression unlike the triumph piston. Its oem yamaha so hopefully of known good quality.

Its worth a go I think, and as its slightly smaller diameter than the triumph piston the barrel can be rebored later to suit the triumph piston if it doesnt work out.
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New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Online Butch (cb)

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Re: B31 & small BSA bikes
« Reply #13 on: 16.10. 2014 09:30 »
I had a '50 plunger B31 some years back, it seemed very slow. With hindsight I suspect I was just treating it too gently. I sold that one - somewhat regrettably now.

My only other BSA is a Bantam. I'm not keen on these - but it was my wife's first bike and a project for this Winter. I've found some lightweight girders to put on the front and will be bolting a rigid rear triangle on. Adding lightness and going for a kind of board tracker look.
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Offline Bikergrandad

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Re: B31 & small BSA bikes
« Reply #14 on: 21.10. 2014 14:13 »
 Hi to all.  Come on lets see some of your smaller bikes. This is one of mine.
               BSA Bantam 125cc D1 1953 it was a wreck I hope the photos come out ok. Bob.
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Too Old To Die Young.
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