Has it taken in fuel, or just poorly adjusted?
I’ve put the float in a jar full of petrol and will see what happens.
I may be wrong, but if it was taking in petrol, the float would sink to the bottom, and the bowl would be full of fuel, as the needle would have dropped with the float.
As there was only a couple of mm of petrol, it sounds like the needle is being held closed or is jammed.
Lever is adjusted perfectly and moves freely but movement could have freed up because I took lid off? Ie was jamming down? There’s no petrol in the float. Will keep looking!
Only way it can be low is if there is a blockage in the delivery pipe ,
What was the time scale from last running the engine to removing the tops ?
The front carb feeds the auxiliary starter carb , so fuel may evaporate faster !!
Don’t forget - most carburetor problems are electric
My reaction to the initial inquiry is that the ignition system is marginal under load with high cylinder pressures, exacerbated by cold temperature and probably poor mixture distribution.
If no petrol in the float bowl check that the float valve is not stuck closed. Mine was.
I filled the float bowl with petrol, left the lid off and a day later it is gone. I’m assuming it can only be evaporation? Probably hitting 40 degrees celcius./104 Farenheit in the garage.
Side note - also make distilled liquor in the same garage - lost 12 litres of my 25 litre open fermentation to evaporation last month. That was heartbreaking - moving to a completely closed system.
I wonder where all the fuel went , feeding the fires in Oz is my guess