8-stroking on choke

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May 11, 2007
Basically my problem is that when the choke is on (single Amal Mk2, so technically it’s an enrichener, I know…), the bike starts right up and runs ok for about 10 seconds. Then it starts 8-stroking and only occasionally firing the left cylinder. It only really does it at idle and just off idle, making pulling away from a stop and steady slow-speed cruising pretty dicey. Once it’s warmed up (which takes about half an hour when running on about 1.5 cylinders) the jetting is just about perfect and it runs beautifully. It just hates that enrichener.
This is a problem that’s plagued me ever since I finished my rebuild, but I focused on getting the warm-running problems fixed first. I even went so far as to convert the simple on/off plunger enrichener to a cable operated one so I can adjust it according to how warmed-up the engine is, plus I wouldn’t have to keep taking the float bowl off and trying new enrichener jets. It’s helped, but when cold it’ll either 8-stroke with the choke mostly on, or if I try to close it a bit then the idle will drop off, it’ll most likely stall within a couple seconds, and if I manage to keep it running long enough to get it in gear it will conk out as soon as I let out the clutch even the slightest bit.
I don’t want to mess with the regular idle settings because it runs perfectly once it’s warm, but I seem to be out of adjustment options with just the choke. Any ideas?
Keep the revs up that'll reduce the effect the choke has. While the stalling could be low revs though advanced ignition will do the same thing.

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