Hello Cris, mopedeers,
At 16:58 13-7-00 -0700, you wrote:
>My '78 Puch has a Bing carb. When you start the engine, it idles fast
>with no choke on (our outdoor temp. is at the 100 degree mark these
>days). After a short engine warm up, the idle speed drops to a low,
>uneven, sometime stalling engine speed. When I restart the engine, I
>have to increase the idle speed using the screw provided. I think the
>poor idling is being caused by a rich mixture, however, I can not find a
>idle circut, nor anyway to adjust the idle mixture!!! I have tinker
>with the float setting, hoping this will have some effect, but nothing
>doing..... Any recommendations on how to lean out the idle mixture?
If the carburation settings were OK in the past, there can be no reason for
it to need adjustment now.
Your Puch has an air-leak somewhere, most likely at the oil-seals. Through
the oil-seals leaking air, the mixture us disturbed, resulting in exactly
the symptoms you describe.
Drain the engine oil, replace it and check again after a week riding. If
the oil is thinner, (very) black and smells a bit like gas, it's probably
the seal in on the RH side. You can check the left one pretty easy when you
remove the flywheel cover and look if there is any oil in your ignition area.
Another (less likely) fault could be wrong ignition timing or a leaking
Leave the carb alone, I think it's OK.