Hitchcocks Forum

My Amal Mk 1 concentric is running rich as evidenced by a sooty plug. The bike is otherwise running very well!
Two questions; 1) it's difficult to do plug chops when the ignition key is behind my right shin. Is the culprit likely to be the idling jet coming into play before I switch off after a run?
2) Am I right that the needle controls the flow of petrol through the main jet at middle throttle settings? I have the needle on its lowest setting, ie top groove. Will a smaller main jet make any difference in the middle range?

Do you have a decompressor? If you do, you can use it to stop the engine. Pull the clutch lever, then immediately pull the decompressor lever and hold it until you have stopped. Then you can swith off the ignition. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.

My Model G doesn't have an ignition switch, so I use the decompressor to stop the engine every time. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.

Good luck! Regards, Anders F. R.

Have you checked float height?

I do indeed have a decompresser, and I use it to stop the engine from an idle.
However, the engine will continue to run with it open if the throttle is open!
Float height might be worth a look; gut feeling tells me its not the problem.