Harley Davidson Sportster (1959 to 1969). Service manual - page 7
ADJUSTING CARBURETOR (See Fig. 3F-7)
The carburetor, once properly adjusted, requires little if any
readjustment. It should not be necessary to adjust the low speed needle
(1) more than 1/8 turn and the intermediate speed needle (2) more than
1/4 turn, richer or leaner, to correct the mixture for a change in
weather conditions.
Before attempting to correct faulty engine performance through
carburetor adjustment, check over "Locating Operating Troubles," Section
1C. In addition be sure air cleaner element is not blocked with dirt and
check manifold connections to be sure they are tight and not leaking
air.
Inlet fitting (7) and vent fitting (8) have strainer screens located in
threaded holes in carburetor body. If faulty carburetion indicates fuel
flow is restricted, remove elbow fittings (7 and 8) from body, extract
both screens with a bent wire, and blow out passages with an air hose.
Replace screens and elbows, being sure that screens are not bent or
damaged so as to allow dirt to pass through.
Check to see that carburetor vent line hose leading from fitting (8) to
gas tank is not blocked off. Also see that gas tank cap vent is not
plugged. Either condition will restrict fuel flow.
