Float Setting: Top of float 5/64" +- 1/64" below top of surface of carburetor body casting. You can fudge a bit higher due to the ethanol gasoline.
Set Idle Adjustment Screw - 1/2 to 1 1/4 turns open. For richer mixture, turn screw out. Do not idle engine below 300 RPM.
Main Metering Jet Calibrated to flow 254 to 258 cc per minute. Main Vent Through diffuser (air bleed inside bowl) size .0315" (.80 mm) drill
Step Up Jet - #63 (.94mm) drill size.
Accelerating Pump - Stroke, summer setting (inner hole, short stroke), intermediate setting (center hole), winter setting (outer hole, long stroke). Due to the ethanol poluted gasoline, you may have to experiment with this.
Pump Discharge Jet Size - .0315 inch (.80 mm) drill. Due to the ethanol you may need to enlarge this by .001. Do this only if you have a lean condition.
Carburetor Loading Up Check float level. Wear on lip of float lever will raise float level. Before adjusting, be sure the float lever pin is firmly seated. Reset the float level by bending lip of float lever away from needle to raise level or bend lip toward needle to lower float level. Bend vertical lip of float only. DO NOT PUT PRESSURE ON NEEDLE VITON TIP.
Motor Stalls While Idling Set throttle lever adjusting screw so motor runs approximately 300 rpm, then set idle adjustment screw to specifications. If these adjustments do not correct the trouble, remove idle orifice tube and plug assembly. Clean tube and passages with compressed air. At this point, if the carburetor has not been rebuilt in the last 12 months, then do so now.
Acceleration Not Satisfactory Remove pump jet and clean with compressed air. Poor acceleration may be due to damaged or worn accelerator pump, sediment in pump cylinder, or clogged intake ball check at bottom of pump cylinder and discharge ball check in discharge passage.
Correct Air Fuel Ratio Provided by a balance tube cast in the air horn. The balance tube should be checked each time the carburetor is serviced to see tht the passage is open. The object of a balanced carburetor is to provide a constant air fuel ratio regardless of type, size or condition of air cleaner. If the air cleaner becomes clogged, the capacity will be reduced but the fuel ratio will not be changed.
Excessive Richness Above 50 miles per hour may be caused by a clogged main vent tube.
Pump Adjustment Remove air horn assembly, back out the throttle adjustment screw, and place pump operating link in center hole of throttle shaft arm. Adjustment can be made by bending horizontal portion of pump connector link, so that top of pump plunger shaft travel is 3/8".
Pump Stroke Adjustable for high and low temperature. Set to longest stroke for cold weather, shortest stroke in hot weather.
Body Flange Assembly (D6A1) (D6C1)
Step Up Piston Spring (Sup by 61-135)
Body Flange Assembly (D6A2) (D6C2)
Flange Gasket for use with governor
Choker Tube Bracket Assy (D6A1) (D6A2)
Flange Gasket for use without governor
Float Lever Pin Retainer
Pump Reatiner Ring
Throttle Shaft and Arm Ass'y (D6A1) (D6C1)
Pump Spring Retainer
Throttle Shaft and Arm Ass'y (D6A2) (D6C2)
Plunger and Rod Assy
Throttle Lever Assembly (D6A1) (D6C1) (Sup by 4-343S)