I felt that the Amal 376 Monobloc carburettor fitted to my Matchless G3LS was a bit worn. I rang Amal…a new one was around £300 plus postage. I then rang Surrey Cycles… who offered me a ‘new’ one for about £160 I seem to remember. They assured me it was ready to fit to my bike and had only seen about a hundred miles of use on another bike.
Amal 376 Carburettor
I ordered and fitted it, just in time for the 2025 Beamish Trophy Trial. On the way to Beamish, the plug sooted up…okay I thought, maybe one of those things, so I cleaned the plug and continued. After leaving Beamish, the plug sooted up again…and the bike felt a little sluggish.
At the roadside, I replaced the plug and dropped the needle one notch to make the mixture leaner and continued. All was well, and I used it several times afterwards on rides.
I was never quite happy with the performance or ‘take up’ after riding with a closed throttle…like you do when descending a hill. I took the carburettor off and found the throttle slide cutaway was a ‘3’ when it should have been a ‘3.5’. I also noticed that the main jet was a 230, not a 210. Time to investigate properly!
It turned out that Surrey Cycles’ carburettor was correctly specified…but for a 1960s competition G3LS, not a 1953 road bike. They are a quite different engine.
I dug out the old carburettor, which had a worn slide. I managed to find, in a box of newly acquired Amal spares, a new 3.5 slide to fit my old carburettor. The end result was that the original carburettor, with a new throttle slide, was fitted to the bike. It works well, performance is as it should be, the plug is the right colour and the take up from a closed throttle is pretty good too.
For reference, the carbs are as follows:
1953 G3LS: Amal 376/5, 1 1/16″ bore, 30 pilot, 106 needle, middle notch, 3.5 cutaway and a 210 main jet.
1960s G3LCS: Amal 376/1616, 1″ bore, 25 pilot, 106 needle, middle notch, 3 cutaway and a 230 main jet.
Surrey Cycles are a good company…it was simply a misunderstanding.