BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: chrisx1 on 05 Jul, 2026, 10:56

Title: Mixture screw
Post by: chrisx1 on 05 Jul, 2026, 10:56
New problem. The mixture screw on my Concentric carb keeps turning itself in to fully closed when the bike is running. It seems very loose, what can I do to prevent this?
Title: Re: Mixture screw
Post by: iansoady on 05 Jul, 2026, 12:52
O ring missing?
Title: Re: Mixture screw
Post by: chrisx1 on 05 Jul, 2026, 13:12
No the o ring is on there and it's a new carb so unless the o ring has shrunk I'm not sure. I will see if I have another one that may tighten things up.
Title: Re: Mixture screw
Post by: chrisx1 on 05 Jul, 2026, 13:33
I just replaced the O ring and it felt better but still a little loose, so I added the old one as well which made it stand slightly proud and a much tighter fit. This feels much better now.