Contents: Idle speed ↓ Composition of the mixture ↓
1. The quality screw on the carburetors in question is sealed after factory adjustment of the mixture composition. Typically, idle speed is adjusted by turning the idle speed screw in the desired direction.
2. Engine performance may vary depending on the degree of wear and tear and the amount of accumulated carbon deposits, which may require changing the mixture composition. In addition, the mixture composition must be adjusted after overhauling the carburetor. Both procedures are described below.
Idle speed
3. Bring the engine to normal operating temperature.
4. Connect the tachometer to the engine, start it again and let it idle.
5. Using the quantity screw (see figure 3.5) achieve the desired idle speed.
Figure 3.5. Disassembled carburetor (section 10): 1 - Retainer; 2 - Choke housing cover; 3 - Gasket; 4 - Top cover; 5 - Washer; 6 - Float chamber needle valve; 7 - Float axis spring; 8 - Float axis; 9 - Float; 10 - Main building; 11 - Main jet; 12 - Spring; 13 - Idle jet; 14 - Accelerator pump diaphragm; 15 - Diaphragm cover; 16 - Spring; 17 - Accelerator pump rod; 18 - Accelerator pump rod nut; 19 - Quantity screw; 20 - Spring; 21 - Quality screw; 22 - Air cut-off solenoid valve; 23 - Throttle lever; 24 - Connecting rod; 25 - Throttle body; 26 - Gasket; 27 - Isolator; 28 - Main jet plug; 29 - Air damper cover; 30 - Spring; 31 - Gaskets and adjusting washers; 32 - Air jet.
Composition of the mixture
6. To accurately adjust the mixture composition, you will need a gas analyzer, the probe of which should be inserted into the exhaust pipe.
7. Check that the engine is at normal operating temperature, disconnect the crankcase breather hose and turn off all electrical consumers.
8. On models with an exhaust gas afterburning system (see section 13) either pinch the system hose, or disconnect and plug it.
9. Break the protective plug above the quality screw.
10. With the engine running at the required idle speed, use the quality screw to ensure that the CO content in the exhaust gases complies with the standard.
11. After completing the adjustment, disconnect the gas analyzer and turn off the engine.
12. Connect the crankcase breather hose.
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