I didn't read you tried cooling down any other components with the spray?
If you say you ran out of options, then how about systematically cooling down ANY involved devices, plugs, cables, coils ?
Cool down one after another and hopefully one of them will be to blame.
You didn't mention using new plugs and maybe plug caps. Use BR8HIX (or BR9HIX if you riding fast/hard very often.)
What about the HT coils. Have you tried exchanging them?
In very rare cases the tach can drain the energy from the capacitor in the CDI. Unplug the grey cable on the tach and unplug the PV controller (both share the tach signal that'll kill the spark if grounded)
And cross check thrice that it's not the tank vent, i.e. the carbs have enough fuel (try transparent hoses for debugging this one)
And do not waste time with the battery, fuses, Power Valve or charging system. That can be completely faulty and it'll still start & run.