Walbro WZ Carburetor Manual

Walbro WZ Carburetor Repair And Service

Walbro WZ Carburetor Manual and Parts List for the correct identification, repair and service of the WZ series carburetor, comonly found on blowers and trimmers. View free online images or download the full PDF which can be printed or saved on any suitable device using a PDF reader. Clear diagrams and information to help in parts ordering or repair of this Walbro WZ series carburetor. Identify all component parts of the Walbro carburetor.

The Walbro model number is stamped on the body of the carburetor

As the clear bulb is depressed an outlet disc is forced against a spring to allow air to escape. When the bulb is released a vacuum is created which pulls an inlet disc against a spring to allow air and fuel from the metering chamber to enter. This procedure must be repeated until the bulb fills with fuel and enters the outlet fitting.

This signifies that the metering system is free of air and the starter box is filled with fuel. At this time the starter button should be depressed and held for 3-4 seconds, this procedure delivers fuel retained in the box to the starting wick which will be drawn into the engine during the starting process.

IDLE ADJUSTMENT OF THE WZ Series Walbro Carburetor

The WZ is equipped with an outer idle limiter for a fine tune adjustment and an inner idle needle for the actual idle mixture setting. Only adjustments to the outer idle limiter should be made by the operator. 

LEAN IDLE CONDITION

A lean idle condition means that the carburetor is getting a higher ratio of air to fuel than the engine requires. Steps to correct this condition are as follows:

1. Turn the outer idle limiter counter-clockwise 2 marks, the idle RPM will drop slightly indicating a richer condition. If the idle appears too rich follow step 2.
2. Turn outer idle limiter clockwise 1 mark. This will put the idle adjustment closer to an optimum setting.

RICH IDLE CONDITION

A rich idle condition means that the carburetor is getting a higher ratio of fuel to air than the engine requires. Steps to correct this condition are as follows:

1. Turn the outer idle limiter clockwise 2 marks, the idle RPM should increase slightly indicating a leaner condition. If the idle appears too lean follow step 2.
2. Turn the outer idle limiter 1 mark counter-clockwise. This will put the idle adjustment closer to an optimum setting.

HIGH SPEED ADJUSTMENT OF WZ (W.O.T.)

The high-speed or W.O.T. needle is pre-set by Walbro at assembly and readjusted to the engine specification by the engine manufacturer.
High speed needle settings may range between 1-2 turns open, see the service manual for the correct settings.
Note: Prior to servicing always record the settings.
RICH W.O.T. CONDITION
A rich W.O.T. condition means that the engine is getting a higher ratio of fuel to air which may cause the engine to exhibit a drop in RPM at high-speed. Steps to correct this condition are as follows:

1. Turn high-speed needle 1/8 turn clockwise.
2. Check engine at W.O.T. with tach for correct RPM.
3. If correct RPM is met do not adjust needle any further.
4. If carburetor requires further adjustment repeat step 1.

LEAN W.O.T. CONDITION

A lean W.O.T. condition means the engine is getting a higher ratio of air to fuel that could cause the engine to exhibit a higher RPM than specified. Steps to correct this condition are as follows:

1. Turn high speed needle 1/8 turn counter-clockwise.
2. Check engine at W.O.T. with tach for correct RPM.
3. If correct RPM is met do not adjust needle any further.
4. If carburetor requires further adjustment repeat step 1.

Walbro WZ Carburetor Manual and Parts List

IMPORTANT: Over adjustment of the high-speed needle can cause severe damage to an engine.

Walbro WZ Carburetor Manual and Parts List Diagrams

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