Uploaded July 2026 | Updated September 2026, 1 week ago

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Having fitted the 2mm compression plate to the 'big bore' B50 it was very clear that a re-tune of the Amal Concentric Mk. 1 carb was needed. I knew the ignition timing was correct, having only recently adjusted it. A good clean and dropping the needle a notch did the job.

01:37 Plug straight after first test run
02:17 1 hour later. Valve lifter oil leak seems to be cured!
02:52 Carb investigation
02:24 Throttle slide
08:50 Ultrasonic cleaner - fluid from allendale-ultrasonics.co.uk
11:28 O Ring 'clipping' on sharp edge
15:14 Another test run
15:35 Back home & debrief