AJS & Matchless Owners Club

Hi I've got a 1960 C31 CSR that sometime in its life has had a 928 concentric carb fitted. Just took it apart to clean service it and found it has a 360 main jet fitted. The pilot and needle are the sane as listed for the mono bloc but the main is different. 360 as against 450. Just wondered why that would be? Do the concentrics s flow differently? Bike seemed to run ok just cleaning the carbs as the bike had just stopped ticking over. Any thoughts?

Concentrics use a main jet 20% less than a monobloc, so it sounds about right.
Dave

Many thanks Dave