Sunday, 28 October 2012


Notes On Rebuilding the Amal Mark 1 Concentric Carburetter 

The Amal Mark 1 Concentric carburetter was introduced onto motorcycles during the 1967 model year. A lighter and more compact carburetter than the preceding Monobloc the name derives from the design of the float chamber around the main jet, an arrangement intended to reduce the effect of fuel surge in the float bowl under cornering and transient throttle conditions. 

The carburetter is currently available in two body sizes; the 600 Series in 22mm, 24mm,  26mm and 27mm bore sizes and the 900 Series in 28mm, 30mm, and 32mm bore sizes. A 1000 Series Concentric in 34mm, 36mm, and 38mm bore sizes was dis-continued during the 1970s. 

Mark 1 Concentric carburetters are available in 4 Stroke and 2 Stroke configurations and can be left or right handed depending on the position of the tickler mechanism and adjusting screws. 

Removing Carburetter

Carburetters should be removed and replaced onto the bike as complete units, with mixing chamber tops and float chambers attached. Failure to do so increases the possibility of warping of the carburetter flange and body.

(a)    Run the engine with the fuel taps closed to empty the fuel from the carburetter, or drain the float bowl by removing the float chamber drain plug.
(b)    Loosen the fuel banjo bolts and remove the banjos.
(c)    Remove the plastic or bronze fuel filters from inside the banjo.

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