This article will cover the procedure of starting up your petrol hedge trimmer engine in cold or warm.

Cold Start – Use this procedure when starting the machine for the first time of the day or after it has been left unused for an extended period.

Warm Start – Use this procedure when restarting the machine shortly after it has been switched off.

Cold Start Procedure

Step 1: Set the Start/Stop Switch

Move the Start/Stop switch to the START position.

Step 2: Apply Full Choke

Move the choke lever to the Full Choke position (diagonal line symbol). This reduces airflow and enriches the fuel mixture, making it easier to start a cold engine.

Step 3: Prime the Fuel System

Press the primer bulb approximately 7 times until fuel can be seen flowing through the bulb.

Step 4: Position the Machine Safely

Place the hedge trimmer on a flat, stable surface. Hold the front handle firmly with your left hand.

Step 5: Pull the Starter Cord

Using your right hand, pull the starter cord sharply until the engine attempts to start.

Step 6: Move the Choke to Run

As soon as the engine attempts to run, move the choke lever to the Run position (vertical line symbol).

Step 7: Start the Engine

Pull the starter cord again until the engine starts and runs.

Step 8: Allow the Engine to Warm Up

Let the engine idle for 15–30 seconds before operating the hedge trimmer.

Warm Start Procedure

Step 1: Set the Start/Stop Switch

Move the Start/Stop switch to the START position.

Step 2: Set the Choke to Run

Ensure the choke lever is in the Run position (vertical line symbol).

Step 3: Start the Engine

Pull the starter cord until the engine starts and runs normally.

Diagram Guide

Safety Information

Do not operate the hedge trimmer with the choke in the Full Choke position once the engine is running. Always move the choke to the Run position after the engine attempts to start to prevent flooding and poor engine performance.

We hope this article helped solve your issue.

Spark Plug Check

If your petrol hedge trimmer is difficult to start, runs poorly, or will not start at all, checking the spark plug is an important diagnostic step. The spark plug generates the spark required to ignite the fuel mixture within the engine.

Table of Contents

Tools Required

1. Removing the Spark Plug
2. Checking the Condition of the Spark Plug
3. Testing the Spark Plug for a Spark
4. Testing with a Different Spark Plug
5. Reinstalling the Spark Plug

Tools Required

• Spark plug spanner/wrench 
• Wire brush (recommended)
• Clean cloth
• Petrol (for cleaning, if required)

1. Removing the Spark Plug

Step 1

Remove the spark plug cap (also known as the high-tension lead). This is the thick black rubber cap connected to the spark plug.

Step 2

Using a spark plug spanner, carefully turn the spark plug anti-clockwise until it can be removed from the engine.

Note: The spark plug may be tight and require some force to loosen.

2. Checking the Condition of the Spark Plug

Inspect the spark plug for signs of carbon build-up, dirt, or damage.

A spark plug covered in carbon deposits may not produce a sufficient spark to start the engine.

Cleaning the Spark Plug

If the spark plug is dirty:

1. Clean the electrode and threaded area using a wire brush.
2. Alternatively, wipe the spark plug with a clean cloth lightly dampened with petrol.
3. Ensure the spark plug is dry before testing or reinstalling.

3. Testing the Spark Plug for a Spark

Step 1

Remove and clean the spark plug as described above.

Step 2

Reconnect the spark plug to the spark plug cap.

Step 3

Position the threaded section of the spark plug against a clean metal part of the hedge trimmer to create an earth connection.

Step 4

Ensure the Start/Stop switch is in the START position.

Step 5

Move to a shaded area where the spark can be seen more clearly.

Step 6

Pull the starter cord firmly while observing the tip of the spark plug.

Result

• A faint white or blue flash indicates that the spark plug is producing a spark and is likely functioning correctly.
• No visible spark may indicate a faulty spark plug or an ignition system fault.

Important Safety Warning: Hold the spark plug using insulated materials and keep hands clear of the electrode during testing to avoid electric shock.

4. Testing with a Different Spark Plug

If available, remove a known working spark plug from another petrol-powered machine.

Step 1

Connect the working spark plug to your hedge trimmer's spark plug cap.

Step 2

Repeat the spark test procedure outlined above.

Results

• If the replacement spark plug produces a spark, your original spark plug is likely faulty and should be replaced.
• If neither spark plug produces a spark, the fault may lie within the ignition system, such as the ignition coil.

In this case, further inspection or replacement of the ignition coil may be required.

5. Reinstalling the Spark Plug

Once testing and cleaning have been completed:

Step 1

Carefully screw the spark plug into the engine by hand to avoid cross-threading.

Step 2

Tighten the spark plug securely using the spark plug spanner.

Step 3

Reconnect the spark plug cap, ensuring it is fully seated and securely attached.

If your petrol hedge trimmer is running at unusually high engine speeds (high revs) when idling, there are a few checks you can carry out before seeking further assistance.

Check the Choke Position

Ensure that the choke is fully disengaged and set to the Run position.

If the choke remains partially or fully engaged after the engine has started, it can affect engine performance and cause the engine to run incorrectly.

Reset the Throttle Hold

Some hedge trimmers feature a throttle hold or fast-idle function to assist with starting.

To reset this:

1. Hold the hedge trimmer securely.
2. Press and release the throttle trigger.
3. Check whether the engine speed returns to a normal idle.

Inspect the Throttle Cable

A sticking or damaged throttle cable may prevent the throttle from returning to its normal position.

Check for:

• Kinks in the cable
• Signs of wear or damage
• Restrictions preventing the cable from moving freely

Important: Accessing the throttle cable typically requires partial disassembly of the machine. This should not be undertaken as it will invalidate any warranty.

If the engine continues to rev excessively after completing these checks, further inspection or repair may be required by a qualified technician.

If your petrol hedge trimmer starts but stalls or cuts out when the throttle trigger is released, the engine may not be idling correctly.

This guide covers the basic checks you can perform before considering carburettor adjustment or repair.

Table of Contents

1. Preliminary Checks
2. Carburettor Adjustment – Low Speed (L) Screw
3. Unable to Perform This Procedure?

Preliminary Checks

Before adjusting the carburettor, ensure the following checks have been completed:

Fuel

Ensure the fuel is fresh and mixed correctly according to the manufacturer's recommendations.

Old or incorrectly mixed fuel can cause poor engine performance and prevent the machine from idling correctly.

Air Filter

Inspect the air filter and ensure it is clean and free from debris.

A blocked air filter can restrict airflow and affect the engine's idle speed.

Fuel Cap

Check that the fuel cap is fitted correctly and tightened by hand.

The cap should be secure but not overtightened.

Carburettor

If the above checks have been completed and the problem persists, the carburettor settings may require adjustment.

Carburettor Adjustment – Low Speed (L) Screw

Important: Carburettor adjustment requires a good level of mechanical knowledge. Incorrect adjustment may worsen the issue or cause engine damage.

Tools Required

• Carburettor adjustment tool ("Pacman" type)

Step 1 – Warm Up the Engine

Start the hedge trimmer and allow it to run until it reaches normal operating temperature.

Step 2 – Locate the Adjustment Screws

The carburettor has two adjustment screws:

• L (Low Speed) – Controls idle and low-speed operation.
• H (High Speed) – Controls maximum engine speed.

Step 3 – Adjust the Low-Speed (L) Screw

Carefully adjust the L screw until the engine idles smoothly without stalling.

The engine should tick over comfortably while the cutting blades remain stationary.

Step 4 – Adjust the High-Speed (H) Screw

With the machine running at full throttle:

1. Turn the H screw anti-clockwise until the engine begins to struggle to reach maximum RPM.
2. Slowly turn the screw clockwise until the engine returns to maximum RPM and runs smoothly.

Once completed, release the throttle and check that the machine returns to a stable idle speed.

Unable to Perform This Procedure?

If you are not confident carrying out carburettor adjustments, we recommend that you do not proceed.

Attempting to dismantle or adjust components incorrectly may invalidate your warranty and could result in further damage.

If your petrol hedge trimmer starts and idles correctly but struggles to accelerate, will not reach full speed, or cuts out when the throttle is applied, this guide covers the initial checks and adjustments you can perform.

Table of Contents

1. Preliminary Checks
2. Carburettor Adjustment – High Speed (H) Screw
3. Unable to Perform This Procedure?

Preliminary Checks

Before adjusting the carburettor, carry out the following checks:

Fuel

Ensure the fuel is fresh and mixed correctly according to the manufacturer's recommendations.

Old fuel or an incorrect fuel mixture can cause poor engine performance and prevent the engine from reaching full revs.

Air Filter

Inspect the air filter and ensure it is clean and free from debris.

A blocked air filter can restrict airflow and reduce engine performance.

Fuel Cap

Check that the fuel cap is fitted correctly and tightened by hand.

An incorrectly fitted fuel cap can affect fuel delivery and engine operation.

Carburettor

If the above checks have been completed and the problem remains, the carburettor settings may require adjustment.

Carburettor Adjustment – High Speed (H) Screw

Important: Carburettor adjustment requires a good level of mechanical knowledge. Incorrect adjustment may cause poor performance, engine damage, or invalidate your warranty.

Tools Required

• Carburettor adjustment tool ("Pacman" type)

Step 1 – Warm Up the Engine

Start the hedge trimmer and allow it to reach normal operating temperature.

Step 2 – Locate the Adjustment Screws

The carburettor contains two adjustment screws:

• L (Low Speed) – Controls idle and low-speed performance.
• H (High Speed) – Controls maximum engine speed and acceleration.

Step 3 – Check the Low-Speed Setting

Before adjusting the high-speed circuit, ensure the L screw is correctly set so that the engine idles smoothly without stalling and the blades remain stationary.

Step 4 – Adjust the High-Speed (H) Screw

With the machine running at full throttle:

1. Turn the H screw anti-clockwise until the engine begins to struggle to reach maximum RPM.
2. Slowly turn the screw clockwise until the engine runs smoothly and reaches maximum RPM again.
3. Test the throttle response to ensure the engine accelerates cleanly without hesitation or stalling.

Once adjusted correctly, the engine should rev freely and respond smoothly to throttle input.

Unable to Perform This Procedure?

If you are not confident carrying out carburettor adjustments, we recommend that you do not proceed.

Attempting to dismantle or adjust components incorrectly may invalidate your warranty and could result in further damage to the machine.

If the pull cord on your petrol hedge trimmer has snapped, become frayed, or no longer retracts correctly, we recommend that you do not continue attempting to start the machine.

The starter assembly contains a tension-loaded recoil spring, and repairs may require partial disassembly of the machine.

What Should I Do?

Please contact our Customer Support Team for assistance.

When contacting us, please provide:

• Your machine model number
• Proof of purchase (if available)
• A brief description of the fault
• Photos of the damaged pull cord or starter assembly, if possible

Our team will be able to advise whether a replacement part is available or whether the machine requires inspection by our workshop technicians.

Important Information

Do not attempt to dismantle the starter assembly unless you have the necessary mechanical knowledge and experience.

Unauthorised repairs or modifications may invalidate your warranty and could result in further damage to the machine.

If the engine is running but the hedge trimmer blades are not moving, there are several checks you can perform before seeking further assistance.

Table of Contents

1. Blade Maintenance
2. Check for Obstructions
3. Inspect the Blade Teeth
4. Check the Gear Drive System
5. Further Assistance

Blade Maintenance

Regular blade maintenance is essential to ensure smooth operation and to reduce wear on the drive system.

Lubrication

Ensure that the blades are regularly lubricated using a suitable multi-purpose grease or blade lubricant.

Poor lubrication can increase friction, reduce cutting performance, and place unnecessary strain on the machine.

Cutting Capacity

Do not attempt to cut branches that exceed the machine's maximum cutting capacity.

For models QHTP26 and SLK26B, the maximum recommended cutting diameter is 22 mm.

For all other models, please refer to your product manual for the correct cutting capacity.

Check for Obstructions

Switch off the engine and allow all moving parts to come to a complete stop.

Carefully inspect the blades for:

• Twigs or branches trapped between the blade teeth
• Built-up sap, dirt, or debris
• Any other obstruction preventing blade movement

Remove any debris found before attempting to restart the machine.

Warning: Always wear protective gloves when handling hedge trimmer blades, as the teeth are extremely sharp.

Inspect the Blade Teeth

Examine the blades for signs of damage, including:

• Bent teeth
• Broken teeth
• Excessive wear
• Misalignment

Damaged blades may prevent normal operation and could require replacement.

Check the Gear Drive System

If the blades remain stationary after completing the checks above, there may be an issue with the drive mechanism.

Over time, components within the gearbox can wear, including the drive gears that transfer power from the engine to the cutting blades.

In particular, the drive gear (sometimes referred to as the bull gear) may become worn or damaged.

Important: Inspecting the gearbox requires partial disassembly of the machine and should only be carried out by a suitably qualified person. Unauthorised repairs may invalidate your warranty.

If the fuel lines on your petrol hedge trimmer have become damaged, cracked, or detached, they will need to be replaced to ensure the engine receives a consistent fuel supply.

Before You Begin

You will require two fuel hoses:

• Outlet Hose (longer hose)
• Inlet Hose (shorter hose)

For easier installation, place the replacement fuel hoses in hot water for a few minutes before fitting them. This will soften the material and make routing the hoses through the fuel tank easier.

Understanding the Fuel Line Layout

Outlet Hose (Longer Hose)

The outlet hose is the longer of the two fuel lines.

1. Feed the hose through the fuel tank opening.
2. Attach the fuel filter to the end of the hose inside the fuel tank.
3. Position the fuel filter so it can move freely within the tank and reach the fuel during operation.
4. Connect the external end of the hose to the carburettor fuel inlet.

Inlet Hose (Shorter Hose)

The inlet hose is the shorter of the two fuel lines.

1. Connect one end of the hose to the primer bulb.
2. Connect the opposite end to the appropriate carburettor connection.

This hose allows fuel to be circulated through the fuel system when the primer bulb is pressed.

Final Checks

Before starting the hedge trimmer:

• Ensure all hose connections are secure.
• Check that the fuel filter is attached correctly inside the fuel tank.
• Inspect the fuel lines for kinks, twists, or signs of damage.
• Confirm that the primer bulb fills with fuel when pressed.

Properly preparing your petrol hedge trimmer for storage can help prevent fuel-related issues and ensure the machine is ready for use when needed again.

Note: The accompanying video demonstrates the procedure using a CDB30 grass trimmer. However, the same principles apply to most 2-stroke petrol-powered garden machines, including petrol hedge trimmers.

Winter Storage Procedure

Step 1 – Drain the Fuel Tank

Empty any remaining fuel from the fuel tank.

Fuel left in the tank for extended periods can deteriorate and may leave deposits within the fuel system, particularly during periods of cold weather and condensation.

Step 2 – Run the Engine

Start the machine and allow it to run until it stops naturally.

This helps remove any remaining fuel from the carburettor and fuel lines.

Step 3 – Clear Residual Fuel

Press the primer bulb several times to circulate any remaining fuel through the system.

Attempt to start the engine again.

If the engine does not start, the majority of the fuel has been removed from the fuel system and the machine is ready for storage.

Step 4 – Store the Machine

Store the hedge trimmer in a clean, dry location away from moisture and direct sunlight.

Where possible:

• Keep the machine off the ground.
• Store it in a shed, garage, or other dry environment.
• Protect it from excessive dust and damp conditions.

Additional Maintenance Before Storage

For best results, we also recommend:

• Cleaning the blades thoroughly.
• Applying a suitable blade lubricant or protective oil.
• Inspecting the machine for any signs of wear or damage.
• Cleaning the air filter if required.

Before Using the Machine Again

At the start of the next season:

1. Fill the tank with fresh, correctly mixed fuel.
2. Inspect the fuel lines and primer bulb for signs of deterioration.
3. Check that all controls operate correctly before use.

Following these steps will help maximise the performance and lifespan of your petrol hedge trimmer.