What size Concentr

[Roadrocket649]

Guys,

I would appreciate your ideas on this.


The bike
1958 BSA Super Rocket 650cc
Fitted with a “Spitfire camshaft” (.357)
A 67-1549 cylinder head (1960-1963 Super Rocket Head and 1962-1963 RGS)

The bike is fitted with a 928 Concentric carburettor

Do you believe this is large enough?

Look forward to your comments

Roadrocket

[MG]

A 930 will be a big improvement, your head should already have the according port size. I'm running one on the A10, but with a 356 cam and ported iron head.
Has anyone tried 32mm? Could be a bit over-carbed already?

[Triton Thrasher]

The bike is fitted with a 928 Concentric carburettor

Do you believe this is large enough?

How does it run?

[t20racerman]

I've got a 32mm concentric on my A10 and it runs superb! I had the head gas flowed and the openings widened and upped the Carb size by 2mm and it really is a pleasure to ride. Fast and responsive at all throttle openings and speeds. Cruises at 75-80mph really well with no slowing down up hills.
Give it a try.....

[Roadrocket649]

Hi Trtonthrasher

Don't know yet, as I am still running it in after an engine re-build

Before re-build, it would not go past 70mph, but on dismantling for re-build, the 356 camshaft, and the cam followers were badly worn

A new 357 camshaft and new SRM cam followers have been fitted

But I was curious whether you Guys felt the 928 was large enough for the size of the engine

Roadrocket649

[muskrat]

G'day Roadrocket,
                        at least a 30 but 32 would be better with the 357. I run 2 X 30 on the cafe and a 32 on the A7, both with 357's, great at med to high revs, not a lot down low.
Cheers