Introduced as an economical alternative to the Amal Premier Concentric series of carburetors, the Wassell Evolution range of carburetors feature jets, throttle valves, floats, and needles that are interchangeable with the Amal Concentric series of carburetors. This version is a replica of the Amal 928 right-hand carburetor, as specified for the BSA A65T, B25, C25 models. Triumph also specified the 28mm 900 series carburetors for the TR25W and TR5T models.
The 28mm right-hand Evolution carburetor is intended for use with a matching left-hand version on a dual-carburetor head, although with changes in the jetting, it can be used on a single-carburetor head. The tickler is on the right side of the carburetor body. Supplied with a 3.0 throttle valve, .106 needle jet, and 180 main jet.
In the case of fitment to most single-cylinder BSA and Triumph models, a 3.5 throttle valve and larger main jet will result in improved tuning. A 3.5 throttle valve and 230 main jet is also recommended for the BSA A65 Thunderbolt models. Individual machines may require further changes to jetting to optimize carburetor tuning. When set up correctly, the 28mm Evolution carburetor can be a suitable replacement for earlier machines originally equipped with the 1-1/16″ bore Amal 376 Monobloc.
The mounting flange is fitted to the inlet manifold studs and secured with nuts. The banjo fitting at the bottom of the float bowl is retained with a special bolt that allows introduction of fuel into the float bowl. Supplied with choke assembly.
For our 30mm Triumph/BSA ‘Evolution’ carb set for Triumph and BSA twins click here
For the single right hand 30mm ‘Evolution’ carb for TR6 and TR7 models click here
For our 32mm ‘Evolution’ carb set for Norton models click here