Re: 75 hp Johson Will start only with idle bar up
unless by "carbs cleaned up" you mean "disassembled, soaked overnight in carb cleaner, blew out all passages with compressed air (or aerosol carb cleaner), reassembled with new carb kits, and linked & sync'd after reinstallation", then you aren't done with the carbs.
worn float valves let gas seep through into the cylinders when you stop, slightly flooding the engine for a hard warm start. hi-idle lever compensates by advancing spark and slightly opening throttles.
Also that'll happen if the idle speed is set too low.
