Carb main jet.

[Rex]

What's the thinking on the main jet size for 1951 A7? The supplier fitted a 140, other lists say 160 or even bigger. The bike's not been ridden yet so a plug chop (as much as a plug chop works with modern fuel) hasn't been attempted.
I'd rather have a little too big than a little too small...

[muskrat]

G'day Rex.
What type of carb? The std 276 of 15/16" uses 140. The Star Twin with a 1" 276 uses a 160.
Cheers

[Black Sheep]

160 for a '51 Star Twin though  I have just upped mine to a 170.

[Rex]

Mine's a Star twin too; I think I might very well be trying a 160 and a 170 when she's finally on the road.

[BSA_54A10]

problem is people who should know better have access to original literature so they get supplied with original size jets which is fine if you know somewhere that sells original spec petrol and not unleaded.
As a rule of thumb we went up about 10% to compensate for the lack of fuel in fuel

[Rex]

Thanks for the info. Your remark about suppliers consulting old lists is almost certainly dead-on, and is probably the reason why this carb wasn't good to go straight out of the box.

[muskrat]

Doh Think he's talking about me 
Cheers