Hitachi Choke

Based on the provided illustration, here is how to adjust the choke pulloff (vacuum break):

• Step 1: Hold the choke valve completely closed, and open the throttle to release the fast idle cam.

• Step 2: Apply an outside vacuum source to fully seat the diaphragm plunger.

• Step 3: Measure the distance between the upper edge of the choke valve and the air horn wall, and compare it against the specifications in your data table.

• Step 4: To adjust, bend the connecting link at the loop until the specified gap measurement is achieved.

Adjust the Hitachi Choke

Adjusting the Electric Choke Housing (Fast Idle & Warm-Up)

If your choke stays closed too long (causing black smoke and stalling) or opens too quickly (causing a cold-engine stumble), you need to adjust the circular black choke housing on the side of the carburetor.

1. Cold Check: Ensure the engine is cold. Press the accelerator pedal to the floor once; the thermostatic coil should snap the choke butterfly valve completely shut over the primary barrel.

2. Loosen the Housing: Locate the three retaining screws holding the round black electric choke cap in place and loosen them just enough so the housing can be rotated.

3. Rotate to Adjust:

   • To make the choke stay closed longer (richer/colder climates), rotate the housing counter-clockwise.

   • To make the choke open faster (leaner/warmer climates), rotate the housing clockwise.

4. Set to Marks: Align the index notch on the black housing with the correct tick mark on the carburetor body (typically set to the center/neutral notch from the factory), then retighten the three screws.