User manual YS FZ53

[. . . ] Synthetic or castor oil can be used, or a combination of synthetic and castor. Do not use four cycle fuel due to low oil content. The needle valve should be set so that the engine is running at a rich setting. [. . . ] Mount the propeller and tighten the rear nut. Next, tighten the front nut as shown in Fig. 1. Select a good quality propeller that will turn in the 9, 000 to 11, 000 rpm range. We recommend sizes 10x9-10x10, 11x7-11x8, 12x7-12x8. LOW SPEED ADJUSTMENT This engine is equipped with a new low speed needle valve to adjust the mixture from low to mid throttle. This needle valve is located on the side of the throttle barrel opposite the throttle arm (Fig. 1). Open the low speed needle to 1 turns from fully closed position. The low speed needle valve should be set after the high speed needle valve has been adjusted. Close the throttle gradually to a idle (approximately 2500rpm). Let it idle for 20 to 30 seconds and then slowly advance the throttle. The adjustment is satisfactory at low speed if transition is smooth at this time. If the engine is running rough on idle, the low speed mixture is rich. If the engine starts to speed up and dies on idle or starts to detonate, when advancing the throttle, the mixture is lean. Turn the low speed needle valve clockwise to richen and counterclockwise for a leaner mixture (note that the direction of the low speed needle valve is opposite the high speed needle valve). Adjustments to the low speed needle valve should be 1/8 to 1/4 of a turn increment at a time to achieve smooth throttle response. [. . . ] DO NOT ATTEMPT TO START FULL THROTTLE, AS THIS IS VERY DANGEROUS. INSTALLATION l. Connect the engine to the tank as shown in fig. 1. Since high pressure is applied to the tank, tighten all connections carefully. [. . . ]