The ALM Manufacturing CJ8 Spark Plug is a replacement 12mm spark plug suitable for a wide range of compatible petrol-powered garden machinery and small engines.

Designed for use in equipment requiring the correct CJ8-type spark plug specification, this replacement plug is suitable for many petrol chainsaws, brushcutters, grass trimmers, hedge trimmers, garden vacuums and other small petrol engines.

A properly functioning spark plug is essential for petrol engine ignition. It produces the electrical spark required to ignite the air-fuel mixture inside the combustion chamber, allowing the engine to start and run.

Over time, spark plugs can become worn, fouled or damaged, potentially contributing to difficult starting, engine misfires or uneven running.

Replacing a faulty or worn spark plug with the correct specification can help restore reliable ignition and normal engine performance.

The ALM CJ8 Spark Plug is a practical replacement component for routine garden machinery servicing and petrol engine maintenance.

It is also listed as a comparison part for a wide selection of spark plugs from leading manufacturers, including NGK, Bosch, Denso, Champion-equivalent ranges where independently verified, Autolite, AC Delco, Motorcraft and Prestolite.

For anyone searching for a CJ8 replacement spark plug, 12mm chainsaw spark plug, petrol strimmer spark plug, brushcutter ignition plug or small engine spark plug, the ALM CJ8 offers a convenient replacement option where its full specifications match the engine manufacturer's requirements.

Key Benefits

• Genuine ALM Manufacturing replacement spark plug

• Model CJ8

• 12mm spark plug thread specification

• Suitable for many compatible petrol garden machines

• Ideal for chainsaw servicing

• Suitable for compatible petrol brushcutters

• Suitable for compatible grass trimmers

• Suitable for compatible hedge trimmers

• Suitable for compatible petrol garden vacuums

• Suitable for other small petrol engines requiring the correct specification

• Useful for replacing worn or faulty spark plugs

• Helps restore correct ignition when replacing a defective plug

• Practical spare part for garden machinery maintenance

• Extensive manufacturer comparison reference list

Replacement 12mm Spark Plug for Petrol Engines

The ALM CJ8 is intended for compatible small petrol engines fitted with a 12mm spark plug.

Spark plugs are an important part of an engine's ignition system, generating the spark needed for combustion.

When a spark plug becomes worn or fouled, replacing it with a correctly specified plug may help address ignition-related starting and running problems.

Important: Thread diameter alone does not establish compatibility. The replacement must also match the engine manufacturer's requirements for thread reach, heat range, seat type, electrode gap and terminal configuration.

Chainsaw Spark Plug Replacement

The ALM CJ8 Spark Plug is suitable for many compatible petrol chainsaws requiring this type of spark plug.

A correctly functioning spark plug helps the chainsaw engine start and operate as intended.

If a chainsaw becomes difficult to start or experiences ignition-related running problems, checking the spark plug is a useful part of routine troubleshooting.

Always consult the chainsaw manufacturer's handbook before fitting a replacement.

Petrol Strimmer & Grass Trimmer Spark Plug

Petrol grass trimmers and strimmers rely on an ignition spark to start and run.

The ALM CJ8 is suitable for compatible models that specify the appropriate 12mm spark plug.

Replacing a worn or fouled spark plug can be part of regular strimmer maintenance.

Brushcutter Spark Plug

The ALM CJ8 can also be used in compatible petrol brushcutters.

Brushcutters are frequently used for demanding vegetation maintenance, making routine engine servicing important.

Using the correct spark plug helps maintain the intended ignition system performance.

Hedge Trimmer Spark Plug

Petrol hedge trimmers require a suitable spark plug for reliable ignition.

The ALM CJ8 is a replacement option for compatible models requiring this specification.

It is useful for servicing hedge trimmers where the existing spark plug is worn, damaged or due for replacement.

Garden Vacuum Spark Plug

Many petrol-powered garden vacuums and leaf collection machines use small petrol engines.

The ALM CJ8 is suitable for compatible garden vacuum engines fitted with the correct 12mm spark plug specification.

Ideal for Small Petrol Engine Maintenance

The ALM CJ8 is a useful replacement part for maintaining compatible petrol garden machinery.

Common reasons for checking or replacing a spark plug include:

• Difficult engine starting

• Engine misfiring

• Rough or uneven running

• Visible electrode wear

• Carbon fouling

• Damaged spark plug components

• Routine servicing at the manufacturer's recommended interval

These symptoms can have several causes, so replacing the spark plug will not resolve every engine problem.

Spark Plug Cross-Reference Guide

The ALM CJ8 is listed as comparing with the following manufacturer part numbers.

These are comparison references rather than a guarantee of direct interchangeability. Check the full spark plug specification and equipment manufacturer's recommendations before ordering or fitting.

AC Delco

CS42, CS49, C47W, CS45

Autolite

235, 254, 255, 2995, 2996, XST255

Bosch

WS7E, WS8E, WS9EC, STK 7542, STC 7543

Denso

T20M-U, W14M-US, W14MR-U, W14M-U, W14M-U10, W20M-U, W20M-US, W22M-U, W22M-US, 6015, 6016, 6019, 6022, 6026, 6034, 6036, 6039, 6048

General Motors

5613234, 5612891, 5613322, 5613166

Mega-Fire

SE-8JC

Mopar

4419643

Motorcraft

A3NX, A7NX, AR7N, STK 118, STK 94

Newstar

L5C

NGK

BM4A, BMR4A, BM6A, BM7, BM7A, STK 5728, STK 5921, STK 6321, STK 6521

Prestolite

14-7N, 14-11X, 14-11N, 14-3N

How to Check Spark Plug Compatibility

Before purchasing the ALM CJ8 Spark Plug, check the existing spark plug or consult the engine manufacturer's handbook.

Confirm the following:

• Thread Diameter: The engine requires a 12mm spark plug.

• Thread Reach: The plug length matches the engine's specification.

• Heat Range: The replacement has the correct thermal characteristics.

• Seat Type: The sealing arrangement matches the cylinder head.

• Electrode Gap: The gap is set to the engine manufacturer's recommended value.

• Terminal Type: The plug is compatible with the ignition lead connection.

A matching cross-reference number can help identify a potential replacement, but the full specification should always be checked.

How to Replace a Spark Plug

1. Switch off the petrol engine and allow it to cool completely.

2. Disconnect the spark plug lead.

3. Clean the area around the existing spark plug to prevent debris entering the engine.

4. Carefully remove the old spark plug using a suitable spark plug socket.

5. Check the removed plug against the ALM CJ8 and confirm compatibility.

6. Check the replacement plug's electrode gap against the engine manufacturer's specification.

7. Carefully start the new spark plug by hand to avoid cross-threading.

8. Tighten it to the engine manufacturer's recommended torque.

9. Reconnect the spark plug lead securely.

10. Start the engine according to the equipment manufacturer's instructions and check its operation.

Important: Do not overtighten the spark plug or install it if the thread size, reach, heat range or seat type is incorrect. Incorrect spark plugs can damage the engine.

Ideal For

• Petrol chainsaw servicing

• Petrol grass trimmer maintenance

• Petrol strimmer repairs

• Brushcutter maintenance

• Petrol hedge trimmer servicing

• Petrol garden vacuum maintenance

• Small petrol engine repairs

• Replacing worn spark plugs

• Replacing fouled spark plugs

• Routine ignition system servicing

• Garden machinery workshops

• DIY garden equipment maintenance

Product Information

Brand: ALM Manufacturing
Product: CJ8 Spark Plug
Model / Part Number: CJ8
Type: Replacement petrol engine spark plug
Thread Diameter: 12mm
Suitable for Chainsaws: Yes, where compatible
Suitable for Brushcutters: Yes, where compatible
Suitable for Grass Trimmers: Yes, where compatible
Suitable for Hedge Trimmers: Yes, where compatible
Suitable for Garden Vacuums: Yes, where compatible
Other Applications: Compatible small petrol engines
Cross-Reference Brands Listed: AC Delco, Autolite, Bosch, Denso, General Motors, Mega-Fire, Mopar, Motorcraft, Newstar, NGK and Prestolite
Primary Use: Replacing the spark plug in compatible petrol-powered garden machinery and small engines.

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You can return your old product to MyDIY. Waste Electrical and Electronic Equipment (WEEE) is taken back free of charge on a one-for-one, like-for-like basis. Waste batteries including rechargeable batteries are taken back free of charge. You are not obliged to make any purchase when returning old batteries. Each local authority must also accept household WEEE and small batteries free of charge at its recycling facilities. All WEEE and waste batteries must be recycled and should not be placed in any of your household wheelie bins. Make sure you always recycle all your old electrical goods and batteries.

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You can return anything that is electricaly powered or battery powered. Even your old bicycle lamps can be recycled!.

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Yes we do. The batteries that we accept are AA, AAA, C or D, powertool batterys and also the flat batteries that are found in watches and toys. Unfortunately we do not accept back any Industrial or car batteries.

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  Date: 19/02/2019