This document describes the working principle and features of the O.S. 2B-2CB-D-2CK automatic fuel supply system. The system incorporates an automatic mixture control device that ensures a correctly balanced mixture of fuel and air for the engine at all throttle settings. The device reduces the effective size of the fuel jet orifice as the throttle is closed, preventing the engine from running too rich at low speeds. Additionally, the system no longer requires an airbleed, maintaining maximum suction at the fuel jet. The document also provides instructions for adjusting the system and notes on different fuel and climate conditions.
This manual provides instructions for the O.S. 2B, 2CB-D, and 2CK automatic carburetors. It describes how the automatic mixture control device works to ensure a balanced fuel and air mixture at all throttle settings, eliminating the need for an airbleed. The document explains that under average operating conditions, the carburetor functions satisfactorily as factory set, but users may need to adjust the needle-valve for maximum r.p.m. and the mixture control screw for idling speeds.
| Idle Speed Range | 2,500 and 3,000 r.p.m. |
|---|---|
| Mixture Control Screw Adjustment | 10 ~ 20 degrees clockwise or counter-clockwise |
Turn the Throttle Rotor Set-Screw counter-clockwise to reduce the throttle opening if the engine runs too fast.
It progressively reduces the effective size of the fuel jet orifice as the throttle is closed to prevent the engine from running too rich at low speeds.
Remove the carburetor from the engine, immerse the parts in solvent such as gasoline or alcohol, and clean them thoroughly before re-assembling.