BSA M20 Piston rings

[davben23]

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

[Dean Southall]

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.

[davben23]

Excellent Dean thanks for the reply 👍

[craigc11g]

then more of a fiddle trying to drop the barrel back on feeding the rings , take the mag dyo off and make life easy .

[Mike Farmer]

 

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

[Blackthou]

Yes, I've used that method too Mike. Often handy to have sometheing to rest the barrel on so both hands are free.

[davben23]

Ah great idea Mike I'll definitely try that method cheers

[Mike Farmer]

 

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

[Pete C]

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

[Mike Farmer]

 

What a good idea---thanks

Mike

[davben23]

Wow great help and replies guys thanks its much appreciated
Dave