Author Topic: Stuck piston in BSA B21 (like a B31 sort of)  (Read 326 times)

Online KiwiGF

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #15 on: 06.10. 2019 05:20 »
I use my log splitter to press in bearings and do jobs like freeing up stuck pistons. I agree with previous entry, soak in diesel for a long time.

Thanks, I think I read somewhere diesel is as good as any expensive “penetrant” wonder chemical!
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

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Online RDfella

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #16 on: 06.10. 2019 09:28 »
Are you sure the rod is still in there, or did it disappear through that hole?
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline berger

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #17 on: 06.10. 2019 11:52 »
I've got a home made ten tin press, but I'm hoping to not resort to that as it will damage the piston for sure, but as a last resort I'll use it. is the ten tin press for destroying ten 1970's skodas in one go *bash*

Online KiwiGF

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #18 on: 06.10. 2019 11:56 »
Are you sure the rod is still in there, or did it disappear through that hole?

That is what I’m trying to find out! All will revealed soon, I tried some more heat and oil this evening but there is no signs of piston movement yet when using the clamp to apply pressure, so given all the advice here I reckon I should next split the cases and have a look inside.

I can put the cases back together if the lower part of the barrel is not too rusty and there’s a chance I can move the piston without using a press or dissolving it, and if it’s easier to handle assembled, and there is also the suggestion of splitting the crank to think about, assuming the big end looks rusty, which it almost certainly will do.

 There was oil On the piston top, and in the rocker area, and not too much rust elsewhere eg the cam followers had surface rust but pressed out quite easily through the brass bushes, so there is still a faint hope it comes apart “normally”.
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Online ironhead

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #19 on: 06.10. 2019 22:56 »


Well that’s good news on the piston availability, I assumed a piston and/or rings would be hard to source, I’m assuming there is no chance of saving the rings, and only a remote chance of avoiding a rebore and subsequent oversized piston, which company sells the pistons please? (It’s a 1937 B21 deluxe), 250cc).


C10 /C11.  From any company you choose.
SA

Online KiwiGF

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #20 on: 11.10. 2019 11:24 »
Well I tried my home made press (20 tonne jack) but chickened out after after putting a fair pressure on the piston, it didn’t move at all, I’m thinking the cases would give way before the Piston.

Muskrat was right and I could not split the cases as the through bolts fouled by just 3mm and hence just stopped me pulling the cases apart. I could try to melt the bronze holding the centre nuts on the through bolts in place and slide them down the 3mm, but decided to leave them alone for now.

So the engine (barrel and piston) is currently sitting in diesel as per prior suggestion, I’ll report back in a month after it’s been soaking a bit. Oddly the piston is under size, and the barrel sleeved slightly under sized. I suspect it has a Nissan car piston.

I’m still not sure if I’ll take this project on rather than sell it, but it’s becoming an “affair of honour”  *eek*.

I’ve spent a couple of hours on google looking at pics, and it looks like not many of these early pre war “B” series bikes (B20 through to B26) are original, so maybe it may be viable to get this one back on the road, wrong tank and all  *dunno* it would involve making lots of parts (stand, gear change etc etc). Random pics of a complete one below (not 5he basket case I have)


 
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Online RichardL

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #21 on: 11.10. 2019 12:13 »
You say, "barrel and piston" in diesel. Is the bore in diesel below the piston? In other words, is the whole engine submerged?

Richard L.
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Online Greybeard

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #22 on: 11.10. 2019 13:40 »
... It could be the stone jar of mercury that I used to empty out and play with when I was a young en...
I also know what mercury feels like, running through my fingers.  *smile*  *countdown*

Online KiwiGF

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Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #23 on: 11.10. 2019 21:53 »
You say, "barrel and piston" in diesel. Is the bore in diesel below the piston? In other words, is the whole engine submerged?

Richard L.

It’s upside down in 10l of diesel, it’s covering the base gasket area by 15mm so diesel can get into the barrel and fill the under piston area (cases are split, with 3mm gap). I also put the diesel in by pouring it through the sump opening, onto the Conrod, so that should also have made sure the barrel was filled.

Fingers crossed this works, it’s going to be messy  *eek*
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet