CARBURETION

TM 5-4240-501-14&P CARBURETION Two Piece Flo-Jet Press new seat flush with body using screw and old seat as a driver. See Fig. 91. Use care to insure seat is not pressed below body surface or improper float to float valve contact will occur. Install float valve as shown in Fig. 93. Fig. 93 - Float Valve Variations Checking Float Level With body gasket in place on upper body and float valve and float installed, the float should be parallel to the body mounting surface. If not, bend tang on float until they are parallel. DO NOT PRESS ON FLOAT TO ADJUST. Fig. 94A and 94B. Fig. 94 - Checking Float Level Assemble Carburetor Assemble venturi and venturi gasket to lower body. Be sure holes in the venturi and venturi gasket are aligned. Most models do not have a removable venturi. Install choke parts and welch plug if previously removed. Use a sealer around the welch plug to prevent entry of dirt. Stake welch plug at least twice. Fasten upper and lower bodies together with the mounting screws. Screw in nozzle with narrow blunt screw driver #19061 or #19062, being careful that nozzle tip enters the recess in the upper body. Fig. 95. Tighten nozzle securely. Screw in needle valve and idle valve until they just seat. Back off high speed needle valve 1- 1/2 turns. Do not tighten packing nut. Back off idle needle valve 3/4 turn. These settings are approximately correct. Final adjustment will be made when engine is running. NOTE: All carburetor adjustments must be made with the air cleaner installed. Fig. 95 - Assemble Carburetor Carburetor Adjustment Start engine and run to warm up. Then place governor speed control lever in "FAST" position. Turn high speed needle valve in until engine slows (clockwise - lean mixture). Then turn it out past smooth operating point (rich mixture). Now turn high speed needle valve to midpoint between rich and lean. Next, adjust idle RPM. Rotate throttle counterclockwise and hold against stop. Adjust idle speed adjusting screw to obtain 1750 RPM, aluminum engines; 1200 RPM, cast iron engines. Holding throttle against idle stop, turn idle valve in (lean) and out (rich). Set at midpoint between rich and lean. Recheck idle RPM. Release throttle. If engine will not accelerate properly, the carburetor should be re- adjusted, usually to a slightly richer mixture. Fig. 96 - Adjusting Carburetor Governed Idle To adjust for governed idle, refer to Section 4 for specific model of engine. Choke-A-Matic Remote Control Adjustment On Choke-A-Matic carburetors, the remote control must be correctly adjusted in order to obtain proper operation of the choke and stop switch. For adjustment, see Section 4. 26