On 19-Sep-2006, Peter wrote:

I have done some test runs today and found that the problem can be
repeated if one quite decisively pushes the throttle shut - that drops
the RPM from 700 to about 500. It happens only when the engine is
warm; say CHT of 330F or higher. The mixture doesn't really affect it.

So it seems OK, but I might inspect the throttle linkage anyway.


This sure suggests that the problem lies with the throttle idle stop,
possibly a mechanical misalignment between the stop adjustment ant the cam
on the throttle control that is supposed to hit it. The misalignment may be
temperature related, i.e. the cam/stop orientation changes just a bit
between cold and hot conditions.

At any rate, if the engine otherwise runs fine this does not seem like a
serious problem.

-Elliott Drucker