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View Full Version : How to adjust Idle and mixture?



4to8m8
03-15-2020, 05:37 AM
Greetings gents-without any fancy equipment is there basically a default way to start with the idle and mixture screws on a 2.25 L petrol?

80sailor
03-16-2020, 12:53 PM
Generally the initial mixture setting is 1 1/2 turns from closed to start with. Then open an close while listening to the engine for smoothness.

erik88lr
03-16-2020, 08:59 PM
Well.... after the compression is checked, the valves adjusted, the ignition system up to snuff and timing set right, the engine can be warmed up and the carb settings done.

The idle mixture affects only the mixture at idle, the idle speed setting only the idle speed with the throttle closed. All pretty obvious.

To cut to the chase, I've always set the idle speed to something reasonable, then adjusted the mixture to make the idle as fast and smooth as possible. Then reset the idle speed if it was too high, and played with the mixture some more. If you have a meter that displays RPMs that might make it easier, but I haven't used one in years.