Replace, as necessary, with the correct sizes to adjust the air/fuel ratio at cruise or under power.

• A. Venturi
• B. Float Bowl
• C. Air Filter
• D. Primary and Secondary Jets

Answer: (D)

Jets control how much fuel is metered into the airstream. By swapping in different jet sizes, you fine-tune the air/fuel ratio for different operating conditions. In a carbureted setup with two jet circuits, the primary jets handle idle and part-throttle operation, while the secondary jets supply extra fuel at higher throttle or full-power moments. Replacing these jets with the appropriate sizes lets you lean or enrich the mixture where it’s needed—cruise versus power. The venturi mainly governs air flow and the suction that pulls fuel through the jets, but changing its size isn’t the typical method used to adjust mixture for different speeds or loads. The float bowl simply stores fuel, and the air filter affects air intake restriction, not metering. Thus, the most effective way to adjust A/F across cruise and power ranges is by selecting the primary and secondary jets.