All cylinders should have equal compression, and there should be no air leaks, however small. When these points have been checked and everything found, or made right, the engine should be started and run under slightly open throttle until it is thoroughly warmed up.
When the proper size of Idling Device has been determined it will be found better to work the stop screw (which prevents the throttle closing tighter than desired) and the Idling Adjusting Screw together in obtaining the "final adjustment". Catch the Stop Screw with a small screw driver, and with the thumb and finger of the other hand grasp the Idling Adjusting Screw, then slowly turn the Stop Screw in or out to bring the engine to its desired idling speed, at the same time turning the Idling Adjusting Screw to make the mixture leaner or richer as may be necessary. Usually it will be found possible to turn out on the Idling Adjusting Screw as the throttle is brought nearer to the closed position. When the desired adjustment has been obtained lock the Adjusting Screws in place.
The FOREGOING refers particularly to Vertical Models. The Idling Adjustment on the Horizontal Models is obtained by turning the knurled screw "up" to enrich the mixture and "down" to obtain a weaker mixture. (See bulletin No4) In obtaining the final adjustment the idling adjustment and throttle adjustment should be worked together as described above.
NOTE: When making the idling adjustment have it on the "rich" side That is, have the Idling Adjusting Screw adjusted to a point where a slight "turn in" would result in a rich mixture.