Author Topic: Stuck piston in BSA B21 (like a B31 sort of)  (Read 1311 times)

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
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!
Good Advice
0
No reactions
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 RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 1007
  • Karma: 8
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?
Good Advice
0
No reactions
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Online berger

  • Wise & Enlightened
  • *
  • Join Date: Nov 2017
  • Posts: 1333
  • Karma: 7
  • keith.chesterfield uk 500sscafe.norbsa project
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*
Good Advice
0
No reactions

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
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”.
Good Advice
0
No reactions
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 ironhead

  • A's Best Friend
  • ***
  • Join Date: Feb 2019
  • Posts: 199
  • Karma: 0
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.
Good Advice
0
No reactions
SA

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
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)


 
Good Advice
0
No reactions
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 RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5194
  • Karma: 50
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.
Good Advice
0
No reactions
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020. This year it's a solo or pillion ride in dapper attire. Watch website at https://www.gentlemansride.com for details.


Online Greybeard

  • Jack of all trades; master of none.
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 6431
  • Karma: 36
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*
Good Advice
0
No reactions

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
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*
Good Advice
0
No reactions
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 Rocket Racer

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 1487
  • Karma: 16
  • A kiwi with a racing A10 rig and too many projects
    • NZ Classic Sidecar Racing
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #24 on: 18.10. 2019 03:49 »
You might also like to put an ad in the Southern Star, those motors and their 350 counterparts the B26 are about. At one stage I had several K & YB26 motors.
Try and source a spare motor or parts...
All the prewar 250 and 350 B series had fragile cases and rolling chassis compared to the post war B's but  as they are so light go very well.
Sounds like the piston and bore are going to be pretty stuffed, but barrels are getting scarce so if in doubt sacrifice that piston. Its toast anyway.
How hot have you got that barrel? More heat...
Good Advice
0
No reactions
A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
New Zealand

Offline RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 1007
  • Karma: 8
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #25 on: 18.10. 2019 11:54 »
I reckon a few ounces of Blue Dot would shift it.
Good Advice
0
No reactions
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #26 on: 20.10. 2019 10:36 »
You might also like to put an ad in the Southern Star, those motors and their 350 counterparts the B26 are about. At one stage I had several K & YB26 motors.
Try and source a spare motor or parts...
All the prewar 250 and 350 B series had fragile cases and rolling chassis compared to the post war B's but  as they are so light go very well.
Sounds like the piston and bore are going to be pretty stuffed, but barrels are getting scarce so if in doubt sacrifice that piston. Its toast anyway.
How hot have you got that barrel? More heat...

Hi Tim, all good advice thanks, i’m Still in two minds on whether to keep the b21 project, so I’ll wait a few more weeks to see if the diesel works on freeing it up, my brothers asked if he can dunk his seized Kawasaki kt250 barn find in the bucket of diesel after I’ve finished with it  *eek*
Good Advice
0
No reactions
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 RDfella

  • Wise & Enlightened
  • *
  • Join Date: Aug 2017
  • Posts: 1007
  • Karma: 8
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #27 on: 20.10. 2019 12:09 »
I'd heat that piston as hot as I dared without melting it, let it cool and then put as much pressure on it as I could (much more than a G clamp) and leave the pressure on. Sometimes when something is obstinate, leaving the pressure on for an hour or overnight does the trick. Remember, as the piston is at TDC putting pressure between piston and crankcase will achieve nothing (assuming the conrod is still in there - if the barrel won't lift off it must be).
Good Advice
0
No reactions
'49 B31, '49 M21, '53 DOT, '58 Flash, '00 Firestorm, Weslake sprint bike.

Offline olev

  • Brisbane, Australia
  • Resident Legend
  • *****
  • Join Date: Sep 2008
  • Posts: 518
  • Karma: 3
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #28 on: 20.11. 2019 21:26 »
So, how did we go. The suspense is unbearable.
cheers
Good Advice
0
No reactions

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....)
  • Wise & Enlightened
  • *
  • Join Date: Feb 2011
  • Posts: 1506
  • Karma: 13
Re: Stuck piston in BSA B21 (like a B31 sort of)
« Reply #29 on: 21.11. 2019 03:59 »
    So, how did we go. The suspense is unbearable.
    cheers

    It’s still soaking in the diesel  *smile* other bikes are in the way of getting on with it.

    I’ve actually just been working on my A10, the stand I bought didn’t have the “extension” piece to hook your foot on, i’m used to finding it with my foot but it’s not easy, I’m lending it to a mate for a day long Rally, so I thought I’d better weld on a short length of bar to make It easier for him.

    I was SO pleased to find the stand spring installation tool I made years ago works so well  *work* I was going to weld it in situ but was concerned the DVR2 might get fried, so I took the stand off, I wasn’t looking forward to doing that, which is why I’ve put off doing the job for years, in the end it only took 30 mins  *eek*
    Good Advice
    0
    No reactions
    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)