Remove the air cleaner and backplate following instructions in appropriate service manual.

See Figure 1. Turn fuel valve off. Disconnect fuel hose, throttle cable and choke cable from carburetor.

Remove two locknuts and lockwashers that fasten the carburetor to the manifold.

See Figure 2. Remove three screws and washers (34 and 35), accelerator pump housing (33), spring (32), diaphragm (31). Remove the O-ring (30) from the housing (33).

Remove three screws and washers (34) and float bowl (29).

Remove O-rings (9, 30 and 28) from float bowl (29).

Loosen screw (6), pin (5) and float (23).

Remove inlet valve (21) and clip (22) from float (23).

Remove rubber boot (8) from float bowl (29) and remove accelerator pump rod (7) from rocket arm (44).

Remove plug (27) and unscrew the low speed jet (25). Main jet (26) can be threaded out.

Remove low speed mixture screw (12) and spring (13) (1976-78 only).

Blow any dirt out of the accelerating pump passage. Blow from the side opposite the nozzle to prevent the check valve inside the bowl from closing.

Clean all dirt from inlet valve and valve seat.

Replace the float if it is cracked or damaged.

Clean fuel lines and air filter.

Clean the carburetor body in a cleaning solvent to remove varnish and carbon from the fuel and air passages. Blow dry with compressed air. Reverse the air flow through all passages to remove all dirt particles.

See Figure 2. Install the low speed jet (25), plug (27), main jet (26), spring (13) and low speed mixture screw (12).

Install a new rubber boot (8) on the float bowl (29) and install the accelerator pump rod (7) on the rocket arm (44).

Install the inlet valve (21) and clip (22) on the float (23). Secure the float (23) to the carburetor using pin (5) and screw (6).

See Figure 3. Place carburetor on a flat, clean surface on engine manifold side. This is the "base". Tilt carburetor counterclockwise 15" to 20" from base until float comes to rest.

Use a vernier or dial caliper depth gauge to measure from the carburetor flange face to the perimeter of the float. Be careful not to push on float while measuring.

Check measurement for accuracy. Measurement should be 0.630 to 0.670 in. If measurement is not within given dimension, carefully bend tab to position float at proper level.

Install new O-rings, as applicable, on float bowl. Secure float bowl to the carburetor body using three screws and washers (34).

Install new diaphragm (31), spring (32), O-ring (30) and original housing (33). Secure with three screws (34 and 35).

Fasten the carburetor and new O-ring (20) (1976-1987) or gaskets (46) (Late-1978 and later) to intake manifold using the original lockwashers and nuts. Tighten nuts alternately to 19 ft-lbs torque.

See Figure 1. Connect the fuel hose, throttle cable and choke cable to the carburetor.

Check throttle control and choke cables for binding and proper operation. Refer to the latest applicable service manual for cable adjustment.

Run the float bowl vent line down between the engine and transmission.

Install the air cleaner and backing plate. Tighten the screws to 75-80 in-lbs and bolts to 10-15 ft-lbs torque.

See Figure 2. Adjust carburetor as follows. Turn low speed mixture screw (12) all the way in (clockwise) until it is just seated. Do not overtighten. Back out 1-1/2 turns. With screw in this position, the engine will start but the mixture will be too rich.

Adjust throttle stop screw (10) to make engine idle at desired speed with throttle closed. Turning screw clockwise opens throttle plate for faster idle. Never set idle adjustment to slowest possible speed. An extremely slow idle causes bearing wear, oil consumption and slow speed accelerating difficulties. Recommended idle speed is 700 to 900 RPM.

Make final readjustment on low speed mixture screw 912) after engine is at normal operating temperature. First turn screw in, then out, to see if engine picks up speed or runs more smoothly. Starting and all-around performance will be better with mixture adjustment set slightly richer than leaner. If necessary, make further adjustment on throttle stop screw (10) to obtain correct engine idling speed. During high speed operation, fuel is metered by a main jet (26). Operating conditions, such as high altitudes or hard service, may require a different size main jet other than the standard size. See applicable Parts Catalog or your Harley-Davidson dealer.