Fuel system - Carburettor Clearing blocked jets
Blocked jets, there's always been a remedy if its dirt or a drop of water, not really any need to change them...
Quick clear: Using a strongly gloved hand, rev the engine on the butterfly levers with the air cleaners off, and as soon as the revs start climbing, whack flat of hand over carb mouth until revs drop back and she chokes up, removing hand, to just keep engine running. Slap hand over carbs at different throttle openings, waiting till it gets up on top the 2nd choke main jet finally. Ditto other carb... This is an old trick to suck any rubbish through the jet and if nothing else, upsets any muck and gives it a chance to find a way out.
Alternately, dismantle clean/clear: remove carb top plates and wash, blow out or vacuum out muck at bottom of main jet and emulsifier tube wells. Alt remove same (jets & emulsifier tubes) and clean by inspection. Replace carefully, do not 'graunch' slots as jets are brass!