CG Cutting out when idling

After 4 days over Crimble when not used, the CG is now cutting out on slow
idle. No unusual roughness (as far as I can tell) or spluttering. Just an
annoying need to keep the revs up when stopped.

Doesn't make any noticable difference whether the engine is in neutral or in
gear with clutch in, or whether lights/indicators are on or off.

Background info:
I replaced the spark plug (badly fouled with white deposits which Haynes
said was to do with surplus oil getting into cylinder) and resistor cover
(cracked) 3 weeks ago, running fine since.
I had run the tank about 20 miles into the reserve on the 20th, after which
the bike appeared to be running fine for the two days immediately before
Christmas (when I covered around 50 miles). Wondering whether this could
have resulted in some crud getting into the carb, but am guessing that this
would have shown up fairly immediately, and wouldn't have just affected the
slow idle.
Weather seems reasonably mild, although the bike is somewhat harder to
start.

It's a mystery to me. Constructive suggestions from the cognoscenti would be
most welcome.

 

Is it doing this with the light on or off?
do the lights make any difference to the running of the bike?

 

As stated above, lights make no difference. Ta.

 

More likely to be a blocked fuel tap than crud in the carb, so I'd
check that, but the symptoms seem to be of a blocked or partially
blocked pilot jet, so I'd check that too.

 

Will do. Murky buckets!

 

I started the Pan up yesterday - 1st time for 10 days, during which time it
had been sitting in a very cold garage - its been below freezing here for
most of the last week. It took it about 20 minutes to get properly warmed
up, and it was only then that it would it tick over properly with the
throttle stop in its normal position (I had to wind it up a bit to keep it
going). I put this down partly to the battery being cold - at tick over,
there wasn't enough available power to keep the engine going. On mine, the
lights, etc always make a difference to the idling speed - put the lights
on, the revs drop by 50-100 rpm.

It may be relevant !

 

And the fuel tap would seem to be the one. After cleaning a moderate amount
of crud from the plastic inlet thingy, voila! Beaucoups de
non-cutting-outness.

Many thanks!