Ty Korrigan

Hi Stuart - sounds like the compressed air is effecting your needle valve - I am not sure where you are blowing your saw with compressed air but perhaps turning down the pressure and using a small 1/2" brush would be better.

What is probably happening is that the air is blowing the diaphragm up and opening the needle valve allowing fuel to over fill the metering part of the carb that then floods in to the engine.

If the machine normally runs fine and this only happens when you clean it in this manner then change your cleaning regime. If this is happening all the time - strip the carb including the needle valve and clean with carb cleaner then would fit a new £10 carb kit but make sure you get the FULL kit not the diaphragm and pump foil only.

Cheers

Steve