BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: davben23 on 28 Aug, 2020, 11:47

Title: BSA M20 Piston rings
Post by: davben23 on 28 Aug, 2020, 11:47
Hi guys
Was looking at replacing the rings on the M20 is it possible to remove the barrel in situ as 2 of the bolts look difficult to access or will I have to remove the mag/dyno or even engine out job ?
Thanks in advance  Dave
Title: Re: BSA M20 Piston rings
Post by: Dean Southall on 28 Aug, 2020, 20:24
Yes the nuts by the mag are a fiddle. There is a small box spanner for this job included in the original tool kit but I was not convinced you could get enough leverage with this. I picked up a cheap ring spanner and bent it to fit using oxy-acetylene torch. Works well.
Plenty of room to get the barrel off without having to remove engine.
Title: Re: BSA M20 Piston rings
Post by: davben23 on 28 Aug, 2020, 20:38
Excellent Dean thanks for the reply 👍
Title: Re: BSA M20 Piston rings
Post by: craigc11g on 29 Aug, 2020, 06:53
then more of a fiddle trying to drop the barrel back on feeding the rings , take the mag dyo off and make life easy .
Title: Re: BSA M20 Piston rings
Post by: Mike Farmer on 29 Aug, 2020, 12:32
 :) :) :) :)

I remove the piston fit the new rings, re-fit in the barrel and then put the barell over the con-rod and refit the gudgeon pin.

Just another method. Quite easy.

Mike 8) 8) 8) 8)
Title: Re: BSA M20 Piston rings
Post by: Blackthou on 29 Aug, 2020, 21:24
Yes, I've used that method too Mike. Often handy to have sometheing to rest the barrel on so both hands are free.
Title: Re: BSA M20 Piston rings
Post by: davben23 on 29 Aug, 2020, 22:29
Ah great idea Mike I'll definitely try that method cheers
Title: Re: BSA M20 Piston rings
Post by: Mike Farmer on 30 Aug, 2020, 10:53
 :) :) :)

You will need to pack lots of old rags etc around the con rod so that nothing can go into the casing. like a circlip. I would also put the gasket onto the barrel rather than the casing, that way its less likely to get damaged.

Mike 8) 8) 8)
Title: Re: BSA M20 Piston rings
Post by: Pete C on 30 Aug, 2020, 14:47

a couple of nuts and a spare stud keeps the barrel away from your fingers while you play with the piston / conrod

(https://i.ibb.co/0qCSzrW/SDC12415a.jpg)

(https://i.ibb.co/3h4Chqv/SAMSUNG-DIGITAL-CAMERA.jpg)
Title: Re: BSA M20 Piston rings
Post by: Mike Farmer on 30 Aug, 2020, 19:03
 :) :) :) :)

What a good idea---thanks

Mike 8) 8) 8)
Title: Re: BSA M20 Piston rings
Post by: davben23 on 31 Aug, 2020, 06:51
Wow great help and replies guys thanks its much appreciated
Dave