Answer
Mar 30, 2025 - 10:32 AM
If you're trying to set the carb on your 660cc Acty, you’ll want to start by warming up the engine fully. Once it's at operating temp, find the idle speed screw and the air-fuel mixture screw — usually on the side of the carb.
Turn the air-fuel screw in gently until it seats (don’t force it), then back it out about 1.5 to 2 turns as a baseline. From there, slowly turn it in or out while listening to the engine — you're aiming for the smoothest idle. Once that’s set, adjust the idle speed screw to bring the RPMs to spec (usually around 850–900 RPM for the Acty in neutral).
If it’s running rough even after adjustment, it might be time to clean the jets or check for vacuum leaks — these old carbs are sensitive to gunk and tiny air leaks.
If you're feeling stuck or have no idea on what you're doing, it may be time for you to take a look at the manual. It covers the full procedure, including diagrams and the exact specs based on your engine code, so it’s worth following step-by-step if you want to get it dialed in just right.
Good luck!
