BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Willie Dee on 13 Apr, 2019, 18:11

Title: Fitting barrels
Post by: Willie Dee on 13 Apr, 2019, 18:11
Ok prepared to take stick for asking a silly question. I have the barrels off my Lighting and I am refitting them. I have fitted the pistons to the bores and I hope to lower the pistons and barrels over the con rods and fit the gudgeon pins...I am kidding myself on or will this work? I will have an assistant to hang onto the barrels.
Title: Re: Fitting barrels
Post by: chaz on 13 Apr, 2019, 18:19
normally I fit pistons to rods then barrels onto pistons. I use 3/4" square bars under barrel flange to enable last minute check.
turning crank over to make sure all runs smooth before bolting flange down.
you want to try juggling a square four barrel onto pistons.....not fun.

your way would seem more hassle and more chance of dropping circlip into cases.
Title: Re: Fitting barrels
Post by: DerekAnderson8 on 13 Apr, 2019, 18:28
Quote from: Willie Dee on 13 Apr, 2019, 18:11
Ok prepared to take stick for asking a silly question. I have the barrels off my Lighting and I am refitting them. I have fitted the pistons to the bores and I hope to lower the pistons and barrels over the con rods and fit the gudgeon pins...I am kidding myself on or will this work? I will have an assistant to hang onto the barrels.

i have used both methods and found fitting pistons into bores first is easier if you have prepared first with correct blocks to hold barrels/pistons above block whilst maneuvering rods to position.

Although if you have assistance piston in rods first then lowering barrels can be quicker although easier to snap a ring!

just my opinion

8)
Title: Re: Fitting barrels
Post by: Willie Dee on 13 Apr, 2019, 18:41
No problem with opinions,exactly what I am looking for.
Title: Re: Fitting barrels
Post by: berniej on 13 Apr, 2019, 19:14
Have also tried both ways ( and SQ4 ! ) but would now fit pistons to con rods, support on rods across the cases as mentioned and the lower barrel on to well oiled pistons fitted with the steel band type ring compressors. Then rotate crankshaft to raise pistons so you can get enough space to remove ring compressors.

Found this easier than aligning rods in piston for gudgeon pin insertion and no sideways forces needed.

Cheers,
Bernie
Title: Re: Fitting barrels
Post by: Bess on 14 Apr, 2019, 13:24
Hi,
    Here's an extract from the manual:

Best wishes...
Title: Re: Fitting barrels
Post by: Willie Dee on 14 Apr, 2019, 13:55
Thanks for that,my problem was I only had one ring clamp and it was no use for the barrels over the piston method. Anyway barrels now fitted,with no drama,nothing ended up in the crankcase,result. To be honest I would use the pistons in the barrels first method again. The only issue was my helper kept calling the gudgeon pins,pigeon pins...I think for the rest of my days they are going to be pigeon pins as its now stuck in my head.
Title: Re: Fitting barrels
Post by: Mike Farmer on 14 Apr, 2019, 14:59
 :) :)

I guess this is  a simple personal choice. I use pistons in barrels and find it OK but as always a bit of care is needed.

Mike 8) 8) 8)
Title: Re: Fitting barrels
Post by: chaz on 14 Apr, 2019, 16:12
I never had ring compressors when rebuilding any motors up to 2 years ago, got a nice set.....
still in the box, cant use them, breaking the habit of a lifetime I suppose.. ::)