Dellorto Motorcycle Carburetor Tuning Guide

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A GUIDE TO THE CHOICE, SETTING AND USE OF TAPERED NEEDLE MOTORCYCLE CARBURETORS



1      FUNCTIONS OF THE Carburetor



2      FEATURES

2.1      Carburetor diagram and principal parts

2.2      Operating ranges

2.3      Installation angles

2.4      Engine connections

2.5      Air Intakes

2.6      Construction materials


3      OPERATION, SELECTION OF CORRECT PARTS, TUNING AND USE

3.1      The venturi effect

3.1.1      Selection of the correct Carburetor size

3.2      Fuel supply system

3.2.1      Selection of the needle valve size

3.2.2      Selection of the float

3.3      Starting from cold

3.3.1      Independent starting circuit

3.3.2      Selection of starter emulsion tube and starter jet

3.3.3      The flooding plunger starting device

3.4      Idle systems

3.4.1      Setting the idle with a mixture adjusting-screw

3.4.2      Setting the idle with an air adjusting-screw

3.4.3      Selection of the correct size of idle jet

3.5      Progression system

3.6      Full throttle operation

3.6.1      Full throttle system as usually used on two-stroke engines

3.6.2      Full throttle system as usually used on four-stroke engines

3.6.3      Selection of the throttle valve cutaway

3.6.4      Selection of the tapered needle

3.6.5      Selection of the correct size main jet

3.7      Acceleration mechanism

3.7.1      Diaphragm accelerator pump

3.7.2      Selection of correct pump cam and pump jet

3.7.3      Piston type accelerator pump


4      MULTI-CYLINDER ENGINES

4.1      Idle tuning and adjustment


5      FACTORS WHICH CAN ALSO AFFECT THE CARBURATION

5.1      Changes of fuel 5.2 Changes in atmospheric pressure and air temperature