A mist of water ....in fact just run the windshield-washer-hose(with a restrictor) into the primaries of the carb ...and fire the pump during some WOT shots ...
ORE ... put an actual water-injection system on it ... it will clean EVERYTHING up .... from the intake port to the exhaust port. Put in a grim-looking spark plug in it and WATCH IT turn almost into "brand-new" !
