Sorry.. not really..
personally I tend to use 1.5mm² copper multi stranded wires quite a lot in repairs (that'd be -what- AWG15 ?)
that is usually good for ~15 Amps * and covers most cases without being too thick.
it also fits in most common connectors and thus gives me an easy time working with it.
It's usually overkill for sensors and even most "powered" things don't need anything near 15 amps
(@~13.5V from the regulator that's around 200Watts of power)
then again things like the starter motor or sets of incandecent lights,
most common ground wires and such need bigger wires still.
So it's a good idea to be aware of the powers being fed through.
In your case.. I'd take the same size as 'suggested' by the part you are connecting to whenever possible.
I'd say the carb uses a 1mm² wire [AWG17 ish] for example so I'd stick with that until it's combined with another wire.
that way you unlikely need to wedge a thick wire into a small connector and create an inadvertent short with a stray strand or such.
Some wires will be harder to judge like the CDI or the voltage regulator.. battery or fuses etc.
I usually dial in for the bigger size when in doubt there are very few cases where that could cause issues
(my ecu for example doesn't like a wire to change it's resistance so fixed length and gauge is required for all sensors to work properly)
but on a non fuel injected engine with nearly no sensors at all there is little chance of such things becoming important
'sid
* note: I'm just eyeballing the max amps most of the time.. 10 amps per 1mm² is just so easy to remember..
AND it holds true for well insulated multistranded copper wires
some even exceed that value.. cheap wires doesn't come close but I avoid that at all costs anyways