Oil Check

The oil should be checked every 3000 miles or 3 months, or whenever carburetor operation seems incorrect. Nissan recommends:

Remove the oil cap Nut and check the oil level. Do not add oil if it is between the two lines:

The damper only holds 3cc of oil, so be careful when adding. Just a touch is all that is called for.

Idle Mixture

Adjust the fast idle or "starter interlock", so that when the choke is engaged, it forces the throttle plate open slightly.

Squeeze the choke lever as shown (nozzle will move down). The yellow connecting link will force the throttle open slightly.
Measure the throttle plate opening
0.6 mm
Adjust the amount of opening by bending the link.

Throttle opens by 0.6 mm (measured between edge of plate and throttle bore)

To check the float level, attach a sight glass to the drain plug.

Remove drain plug. Catch gasoline in a cup.
Take a 5/16" hose L-fitting. Fit clear 30mm plastic tubing pointing up, and jam the fitting into the drain hole. Make sure it is secure. Position it parallel to the bowl (straight up/down).
Nissan had a tool for this, number ST19200000 "Float level gauge"
Start the engine and let it idle.
Measure the level of fuel in the tube
- 22-24 mm from fuel bowl gasket
- Adjust float if too high or too low

When replacing the float level needle and seat, set the static level of the float.

Remove Float Chamber cover
Place it upside down and level
Level from top of brass lever to flange (without gasket) should be:
11-12 mm
If needed, adjust lever by carefully (and slightly) bending inner tab of brass lever.

Remove air cleaner
Remove oil cap nut
Stick your finger in the bore. Slowly lift the piston to avoid splashing the oil.
Lift piston about 8mm until it stops
Drop piston. It should click against the venturi stop.
If movement is sticky other otherwise not smooth, remove Suction chamber and carefully clean chamber and piston.

CAUTION: Do not sand. It is a precision fit.

NOTE: There is no gasket between the Suction Chamber and the Throttle chamber.