Re: Tohatsu 4HP 4-stroke Looping idle
What is your model/serial?
Those carbs are pretty accurate, but very sensitive to varnishing in the low-speed circuit, especially on the B model motors. Yes, you could replace the carb. In fact, the carbs for the A model fit and work well on a B model, and are a little less sensitive to varnishing. FWIW, the carbs for the 4, 5, and 6 all interchange, so if buying a new carb, you can upgrade to a 6 hp motor if desired.
I trust you didn't just use spray carb cleaner... it's not strong enough to dissolve varnishing in the carb. A proper carb dip (available in 1- and 5-gallon cans at most any auto parts house) is the correct fluid to use. Follow the instructions... After disassembly, put the carb in the dip basket, and leave it submerbed for the time recommended in the instructions of the can of carb dip. Typically about 3 hours or so. Many of the dips then can be washed out of the carb with hot/warm tap water, then blown out with compressed air.
I usually recommend running the carb dry at the end of the day -- especially if you know the motor will sit for a week or more, and draining it completely if storing the motor. If there's no gas in there to evaporate, it can't spoil and sludge up the carb.
