Idle speed adjustment must be carried out on a warm engine (at a coolant temperature of 90-95°C), with adjusted gaps in the gas distribution mechanism, with the correct ignition timing and with the choke valve fully open.
The adjusting screw 1 of the amount of the mixture is set according to the tachometer of the stand, the crankshaft speed and the limits of 820-900 min-1. Then adjusting screw 2 quality (composition) mixtures achieve a concentration of carbon monoxide (SO) in exhaust gases within 0.5–1.2% at a given screw position 1 (CO concentration is given to 20°C and 760 mm Hg. Art.). Screw 1 restore the crankshaft speed to 820-900 min-1. If necessary, adjusting screw 2 restores the CO concentration to 0.5-1.2%.
At the end of the adjustment, sharply press the throttle actuator pedal and release it. At the same time, the engine should increase the crankshaft speed without interruption, and when it decreases, it should not stall. If the engine is stopped with screw 1, the crankshaft speed is increased within 820–900 min-1.
After adjustment, a new plastic plug is installed in the hole of the adjusting screw 2.
Note. When the screw 2 of the mixture quality is unscrewed, the combustible mixture is depleted, when screwed in, it is enriched.