CARBURETION

TM 5-4240-501-14&P CARBURETION Two Piece Flo-Jet Fig. 85 - Typical Two Piece Flo-Jet Carburetor Check Upper Carburetor Body for Warpage With carburetor assembled and body gasket in place, if a .002" feeler gauge can be inserted between the upper and lower bodies at the air vent boss, just below the idle valve, the upper body is warped or gasket surfaces are damaged and should be replaced. Fig. 86. Fig. 86 - Checking Carburetor Body Check Throttle Shaft and Bushings for Wear Wear between throttle shaft and bushings should not exceed .010". Check wear by placing a short iron bar on the upper carburetor body as shown in Fig. 87. Measure the distance between the bar and shaft with a feeler gauge while holding the shaft down and then holding shaft up. If the difference is over .010", either the upper body should be rebushed, the throttle shaft replaced, or both. Wear on the throttle shaft can be checked by comparing the worn and unworn portions of the shaft. To replace bushings, see "Remove Throttle Shaft and Bushings." Fig. 87 - Checking Throttle Wear Remove idle valve. On small line Flo-Jet loosen high speed valve packing nut. Remove packing nut and needle valve together. On medium and large line Flo-Jet remove high speed valve assembly. Remove nozzle on small line Flo-Jet with 19061 screw driver. On medium and large line Flo-Jet use 19062 screw driver to remove nozzle. Using 19061 or 19062 will help to prevent damage to the threads in lower carburetor body. The nozzle projects diagonally into a recess in the upper body and must be removed before the upper body can be separated from the lower body, or the nozzle will be damaged. See Fig. 85. Remove screws holding upper and lower bodies together. A pin holds the float in place. Remove pin and remove float and float needle as an assembly. Use wide blade screw driver that fits slot to remove float inlet seat. On carburetors with pressed in float seats, see "Replacing Pressed In Float Valve Seat." On small Flo-Jets the venturi is a separate part and can be slipped out of the lower body. Some carburetors have a welch plug. This should be removed, only if it is necessary, to remove the choke shaft or choke plate. Some carburetors have a nylon choke shaft. Remove as shown in Fig. 88. Fig. 88 - Nylon Choke Shaft 24