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Jetting Your CDK II Diaphragm Carburetors

1) IDLE

Set the idle speed to proper r.p.m. by adjusting

the IDLE SPEED SCREW. Next, turn the IDLE

MIXTURE SCREW to get the highest speed,

then turn out the IDLE MIXTURE SCREW

approximately 1/4 to achieve best response.

The IDLE MIXTURE SCREW controls fuel

delivery to the idle port and also contributes

fuel to the SLOW CIRCUIT.

2) OFF IDLE TO 1/4 THROTTLE

The SLOW JET is the most effective in this

range. WHen you want a richer mixture in the

range, use a larger SLOW JET. The opposite

holds true for achieving a leaner mixture.

3) POP-OFF PRESSURE

In most applications it will not be necessary to

change the POP-OFF PRESSURE. If the engine

is modiied or a larger carburetor is used,

changing POP-OFF to a lower pressure may

beneit the calibration. If engine exhibits poor

acceleration or is lean at W.O.T., try lowering

the POP-OFF pressure by using a lighter

spring or a larger valve.

4) WIDE OPEN THROTTLE

Changing the MAIN JET or HIGH SPEED

SCREW adjustment affects this range. Start

adjusting by turning the HIGH SPEED

SCREW until the best performance is

achieved. Then, check number of turns on

the screw. If the screw is adjusted all the way

in, install a smaller MAIN JET. If the screw is

out more than three turns, install a larger

MAIN JET. Continue until optimum

performance is achieved and the HIGH

SPEED SCREW is at approximately 1 to 1 1/2

turns. This will allow some adjustment range

on the HIGH SPEED SCREW to perform

minor adjustments or to compensate for

temperature changes.

Calibration Chart

(for CDK II)

Internal View

NOTE: Make only one

change at a time.

CDK II Diaphragm Carburetors

532

Main Jet

Slow Jet

Fuel Inlet Seat

Needle Valve

Arm

Regulator Spring

Fuel Chamber

Regulator Diaphragm

High Speed Screw

Atmospheric Vent

Idle Mixture Screw

Idle Port

Throttle Plate

Fuel Inlet

Pulse

Pump

Diaphragm

Check Valves

Fuel Return

Restrictor

Vapor Seperator Anti-Siphon Valve

Transfer

Holes

Water

Idle

1/4

1/2 3/4 W.O.T

Throttle Opening

Effectiveness

High Speed Screw

Main Jet

Slow Jet

I.M.S.