Author Topic: Q: BSA A65 L - Cylinder Barrel Correct Part #  (Read 244 times)

Offline adriancw

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Q: BSA A65 L - Cylinder Barrel Correct Part #
« on: July 27, 2021, 07:11:16 PM »
Hi all,

I recently acquired what I thought was a 71 Lightning, and am trying (unsuccessfully) to strip the engine down. After being left outside with no spark plugs in, the pistons are well and truly seized in the barrels...

After trying to unseize for a while (a week now - lots of heat treatment, gentle but persuasive hammering, penetrating lubricant's, and even a dose of Phosphoric acid...) I am thinking maybe I cut my losses,,, 

I should just strip down what I can, get another used set of barrels, and then re-sleeve or re-bore that one with new matching pistons...

According to my parts book the barrels are part # 71-1464.  When I look at the actual seized barrels, they appear to be Part # 71-1033.

The engine VIN on the case is XE 02985 A65L, which I think would be a December 1971.

My question is - what do I look for? The Part # in the book, the Part # on the bike, or will any barrels from an A65 fit???  Thanks  Adrian

Offline Rex

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #1 on: July 27, 2021, 07:22:39 PM »
I'd give it a while longer than a week. A good dose of diesel in the bores (with regular refills) and arrange a pusher across the bores to keep the pressure on. Give the piston tops a regular thumping too, and even a blast from a gas torch on the barrels will help it.

Offline L.A.B.

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #2 on: July 27, 2021, 07:44:00 PM »

According to my parts book the barrels are part # 71-1464.  When I look at the actual seized barrels, they appear to be Part # 71-1033.

Numbers on castings are often the 'casting' or 'foundry' number and not the actual 'part' number and although I don't have a list of casting numbers casting 71-1033 is probably 71-1464.


The engine VIN on the case is XE 02985 A65L, which I think would be a December 1971.

'X' denotes the month of manufacture  (December), however, 'E' denotes model year (1971) which isn't necessarily the calendar year in which the bike was built as production of new the 'year' models began around August of the preceding year so XE would be a 1971 model built December 1970.

L.A.B.

Offline R

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #3 on: July 27, 2021, 11:04:29 PM »
After trying to unseize for a while (a week now - lots of heat treatment, gentle but persuasive hammering, penetrating lubricant's, and even a dose of Phosphoric acid...) I am thinking maybe I cut my losses,,, 

A week eh ?
I had a (lightly ?) seized Triumph engine, and it took 2 years of lubing and heating and tapping to get it loosened off.
And then wasn't really usable.
So finding that replacement cylinder seems like a good plan.

You can at a pinch use an acetylene torch to cut/melt the pistons out ...
This spares the bores any further damage - but they likely will be past it anyway.

Have fun !

Offline john.k

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #4 on: July 27, 2021, 11:15:43 PM »
After soaking,get a small air hammer and give the pistons a good shake up.....stick to the center part,and dont rivet them into the bores......then  the barrels in the freezer,and after 24hrs ,press the pistons out with a hydraulic press from the top.....You will not bust barrels or rods doing this ............For a faster method that destroys the rods,simply fill the barrels and  pistons up full of caustic soda ,add a little water.....and jump out of the way ,sharpish ,before the volcano of caustic dissolves you .......by the way ,do this out in the back yard,not the kitchen ,unless you want to strip the paint off the ceiling.

Offline Vreagh

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #5 on: July 28, 2021, 09:43:55 AM »
I've used the caustic method on A10 barrels. It certainly works and does no damage to the barrel but will dissolve any alloy in touches.

Offline Rex

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #6 on: July 28, 2021, 10:24:52 AM »
Seems a shame to possibly damage the rods though.  :-[

Offline iansoady

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #7 on: July 28, 2021, 10:31:13 AM »
... and indeed the crankcases if the caustic soda gets that far.

I think patience will be your friend on this one.
Ian
1952 Norton ES2
2008 Yamaha X-Max 250

Offline john.k

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Re: Q: BSA A65 L - Cylinder Barrel Correct Part #
« Reply #8 on: July 28, 2021, 01:55:17 PM »
Guy sold  me  a Bonneville once,piston and bearing seizure...$30 .....he had levered the barrels up just enough to get a hacksaw into the gap and sawed off the rods .....certainly made  it lighter .