> Adjusted valves, still same problem. Pulled the plug wire and the
engine
> note is the same. Also shorted the plug wire to ground to check for
spark,
> so I'm thinking it must be something to do with the carb (or at least
one
> side of it).

Gareth,

If the engine speed did not change at all when you pulled the plug wire
then I would suggest pulling that spark plug and inspecting it. You
should see a very pronounced change in the idle quality if you pull a
plug wire. No change at all means you just found a dead cylinder.

You say you verified the valves are set correctly, the next thing I
would check is the plug wire and the spark plug itself. If the plug is
saturated with gasoline and/or black it could still be a
float/carburetor issue, and you would need to clean or replace the plug
to restore the functionality of the ignition in that cylinder. It also
may be as simple as a bad plug wire, I've seen bad wires act up at idle
but once the engine speed is increased they clear up and the misfire
goes away temporarily.

Chris