JFLEISC wrote:
: No rate of advance necessary. Just hold it steady anywhere from 1000 to 1700
: RPM and it is very rough for as long as you stay there.

Hmmm, do you have a carb with a 1-piece venturi? On some applications these
made the engines run so poorly that the 2-pc was allowed to be reinstalled.

Does leaning, even leaning to the point of the engine dying, change the
roughness? Perhaps the carburettor is incorrectly jetted.

Did you look at the distributor blocks in the mags? Or the coils? Perhaps
the increased temperature of running at 1000-1700 with less cooling airflow
is making something conduct that shouldn't?
--
Aaron Coolidge