Carburetor adjustment [Toyota Dyna Y50]

Recommendation: When making carburetor adjustments, use a specialized tool.

1. Adjust the full opening angle of the primary throttle valve of the carburetor.

Nominal angle - 90° from the horizontal plane

If necessary, adjust by bending the throttle limiter.

2. Adjust the full throttle opening angle of the secondary chamber of the carburetor.

(a variant of a carburetor with an additional damper in the secondary chamber)

a) After moving the secondary throttle valve locking lever, fully open the secondary throttle valve and check the opening angle, the nominal value of which is: 90° from the horizontal plane.

b) If necessary, adjust by bending the secondary chamber throttle limiter.

(option without additional damper in the secondary chamber)

a) With the primary throttle valve fully open, open the secondary throttle valve and check its full opening angle.

Nominal angle - 80° from the horizontal plane

b) If necessary, adjust by bending the secondary chamber throttle limiter.

3. (option without additional damper in the secondary chamber) Adjust the forced opening angle of the secondary throttle valve with the primary throttle valve fully open.

a) With the primary throttle valve fully open, check the clearance between the secondary throttle valve and the carburetor body (mixing chamber body).

Nominal clearance for carburetors is 0.20 mm

b) If necessary, adjust by bending the secondary throttle valve forced opening lever.

4. Adjust the primary throttle angle to match the start of the secondary throttle opening.

a) Check the opening angle of the primary chamber throttle valve at which the secondary chamber throttle valve begins to open, i.e. the moment the primary chamber throttle valve push lever touches the secondary chamber throttle valve push lever.

The nominal angle from the horizontal plane is -50°

b) If necessary, adjust by bending the secondary chamber throttle lever:

5. (Carburetors with automatic choke)

Install an automatic air damper.

a) Align the mark on the spring housing with the center line of the thermostat housing as shown in the figure.

Note: The air damper closes completely at an ambient temperature of: 15°C

b) Depending on the operating conditions of the vehicle, turn the spring housing and adjust the mixture composition when starting the engine:

if the mixture is too rich, turn clockwise;
if the mixture is too lean, turn counterclockwise.

6. Pre-set the throttle valve to a position corresponding to increased idle speed when warming up the engine.

(Carburetor with automatic choke)

a) Set the cam of the increased idle speed system during warm-up. To do this, hold the throttle valve slightly open, close the choke valve and, holding it in the closed position, release the throttle valve.

With the choke closed, check the throttle opening angle.

The nominal angle from the horizontal plane for the carburetor is 20 - 22°

b) If necessary, adjust the high idle speed system mixture quantity by turning the adjusting screw during warming up.

7. (Carburetor with automatic choke)

Adjust the angle of forced opening of the air damper with the primary chamber throttle valve fully open ("unloading angle").

a) With the primary throttle valve fully open, check the air damper opening angle, the nominal value of which is (from the horizontal plane):

option with additional damper in the secondary chamber - 50°
option without additional damper in the secondary chamber - 45°

b) If necessary, adjust by bending the "unloading" lever.

8. (Carburetor with FICB (Fast Idle Control Cam) Position Switch)

Adjust the position of the idle speed increase cam switch when the engine is warmed up.

a) Install the cam (see above).

b) Apply vacuum to the FICB switch.

c) Check the mobility of the drive and make sure that the cam is in the third position.

d) If necessary, adjust by bending the FICB lever.

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9. Adjust the air damper (AD) position control ("switch").

Preliminary instructions: While holding the throttle valve slightly open, press the choke plate and close it; while holding the choke valve in the closed position, release the throttle valve. Then measure the choke valve opening angle using the following procedure.

(Carburetors with automatic choke (variant with two diaphragms in the pneumatic drive of the air damper switch))

a) Install the high idle speed control cam (see above).

b) Apply vacuum to the internal diaphragm (A) of the air damper switch (AD).

c) Check the opening angle of the air damper.

The nominal angle (first) from the horizontal plane is - 40°

d) If adjustment is necessary, remove the spring housing and bend the air damper lever.

d) Apply vacuum simultaneously to the inner (A) and outer (B) diaphragms of the CB switch.

e) Check the opening angle of the air damper.

Nominal angle (second): from the horizontal plane is - 55°

g) If necessary, adjust by turning the adjusting screw of the SV switch.

(Carburetor with automatic choke (single diaphragm version in the air damper switch pneumatic drive))

a) Set the idle speed increase cam when warming up the engine (see above).

b) Apply vacuum to the diaphragm of the CB switch.

c) Check the opening angle of the air damper.

The nominal angle from the horizontal plane is -38°

d) If necessary, adjust by turning the adjusting screw of the SV switch in the same way as was done for the switch version with two diaphragms in its pneumatic drive.

(carburetor with manual choke control)

With the air damper fully closed, apply vacuum to the CB switch and check the air damper opening angle, the nominal value of which is 38° from the horizontal plane.

If necessary, adjust by bending the connecting rod.

11. (a variant of a carburetor with an additional damper in the secondary chamber)

Check the additional valve and the metering needle: they should move freely, without jamming and synchronously.

12. Check the accelerator pump.

a) By turning the primary chamber throttle shaft, make sure that the lever and the pump diaphragm pusher move without jamming.

13. Pre-set the primary throttle valve opening angle to match normal idle speed.

a) (Carburetors with a throttle opening mechanism (TP))

Apply vacuum to the throttle valve opening mechanism.

b) (Carburetors with automatic choke) Open the throttle valve and then close it, leaving the choke valve fully open.

Caution: Make sure that the idle speed increase device does not turn on during warm-up.

c) Check the opening angle of the primary chamber throttle valve.

The nominal value of which from the horizontal plane is (approximately) for carburetor - 13°

d) If necessary, adjust by turning the idle speed adjusting screw.

14. Pre-set the position of the mixture adjustment screw (the "quality" screw) to the normal idle speed. If the quality screw was unscrewed, screw the screw in completely and unscrew it by about 3 turns. Do not tighten the screw with force, so as not to damage its conical surfaces.