Author Topic: a10 barrels  (Read 4407 times)

63a10r

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a10 barrels
« on: 24.09. 2006 22:39 »
what is the casting # on a "thick flange barrel?"

Offline LJ.

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Re: a10 barrels
« Reply #1 on: 25.09. 2006 14:33 »
Hi there... Just been out and had a look at mine and the number is 67-1210 these barrels as far as I know are 1961s but of course they may not be originals.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline a10gf

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Re: a10 barrels
« Reply #2 on: 26.09. 2006 03:10 »
Hello, 67-1210 from 1954 a10r, 67-1074 1954-58 a10's. From 1958, 67-1210 for all a10's.
1\2 in base on thick flange block (Bacon's twin restoration).

I've read somewhere about high comp pistons fitted to thin flange 67-253 blocks resulting in the whole top wanting to fly trough the tank...

Regards'
E.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline trevinoz

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Re: a10 barrels
« Reply #3 on: 26.09. 2006 22:36 »
I have gone down the path of 10.5 :1 pistons in thin flange barrels on my '55 Flash. The barrel broke off above the flange within 10 miles! I have also broken thick flange barrels with 8.75:1 pistons, but they had been resleeved.

Offline Beezageezauk

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Re: a10 barrels
« Reply #4 on: 27.09. 2006 21:28 »
During the 1950's, as the years progressed and the A10 engines were developing more and more power, barrels were regularly breaking away from their flanges so BSA produced the "Thick Flange Barrel" in the hope that it would cure the problem.  I think that it probably did when they were sort of new but now, as these barrels are at least 45 years old, they could be suffering from metal fatigue and obviously won't be as strong as they were.
My A10GF is running on a thick flange barrel but I decided to fit low compression pistons in the hope that I would achieve more reliability.  I don't think it makes that much difference to the general running of the bike.  It cruises comfortably at 65mph even 2-up and loaded up with camping gear.  And it hasn't given me any trouble for the 6 years it has been on the road, attending four continental rallies, several British National Rallies and club camps.
However, I will post an interesting story shortly about preparing it for the Danish BSAOC International Rally in 2005.  Worth waiting for??  We'll see and let you be the judge!!   ;) Beezageezauk.   

Offline trevinoz

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Re: a10 barrels
« Reply #5 on: 27.09. 2006 22:44 »
The main problem occurring with barrells now is when they are resleeved there is not much original metal left above the flange, even thick flange types. Stepping the sleeves and brazing top and bottom seems to keep them together. I have had thick flange barrells break with 8.75:1 pistons but with above method of resleeving I have had no problems.