As a restorer and rider of classic motorcycles, and an ex-petrol powered model aeroplane flyer, I believe I have some experience of carburettors.
I'd suggest it's very likely to be a partly blocked pilot jet in the carb. Carb cleaner will only do so much. It needs a strip, a soak and a re-build. Carbs are much more finicky now with modern fuels - it's a major issue for the classic motorcyclists. Ethanol in fuel (aka effinol) rots the fuel lines, primer bulbs and the clunks (the weight on the end of the pickup line in the tank. The muck that then gets into the fuel clogs up the carb jets.
Get a new gasket kit, strip the carb, thoroughly clean it, blow through all the jets (and even poke some fine brass wire - or better - plastic 'wire' into the jets and wiggle about - carefully - you can easily wear away the jets). If you have spark, good fuel and compression, and the jets are clear, it'll run.
I run my bike carbs dry at the end of the season and drain the tanks so the fuel system is dry over the winter.