6 Steps to Replacing Motorcycle Spark Plugs

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  • 1-3 hours
  • Beginner
  • 6-36
What You'll Need
Cleaning agent
Large cloths
Warm water
A air compressor
Spark plug socket/wrench
Penetrating oil
New spark plugs

Motorcycle spark plugs need to be replaced in order to keep a motorcycle running efficiently. If you forget to change the spark plugs at regular intervals, you will gradually lose performance and reliability from your bike. The process is quick and easy to carry out so you do not have to sacrifice too much time or money.

Step 1 - Remove Wires

Spark plugs on a motorcycle should be easily accessible from either side of the bike. The first thing you need to do is wait for the engine to cool down. Use your fingertips to hold the boot, which is easily identified as a little cap on the end of a spark plug. Gently twist the boot until the wire comes free. Do not force the wires off because you will damage them. Twist them gently to the left and right if they are proving stubborn to remove.

Step 2 - Clean Spark Plugs

Use a little cleaning agent and a wet cloth to rub the spark plugs and clean them before you remove them. This may sound strange but it will stop any dirt or debris from falling into the cylinders of the engine when you remove the plugs from their position. A good tip is to use a compressor to blow air over the spark plugs. This will also make replacement of the spark plugs a cleaner experience.

Step 3 - Remove Spark Plugs

Use a ratchet and a spark plug socket to turn the spark plugs in an anti-clockwise direction. Do not be afraid to use extensive pressure because the spark plugs have linings which prevent surface cracks to the case. Turn the spark plugs until they are loose. It should now be easy to spin them out of position using your fingers. Check for any signs of damage to the plugs once you have removed them as this could indicate that debris may have fallen into the cylinder.

Step 4 - Check Cylinder Heads

It is always a good idea to check the cylinder heads before you install new spark plugs anyway. New spark plugs should screw into the cylinder heads easily. If the heads are dirty, give them a quick wipe with a damp cloth soaked in penetrating oil. This will also help with the ignition of the engine. Spray a little penetrating oil over the threads to stop any chance of friction developing when you screw on the new spark plugs.

Step 5 - Install New Spark Plugs

Check plug gap for correct amount for your engine. Fit a new spark plug into position. Screw it into place with your fingers each time. Use your spark plug wrench or socket to give the spark plug a final strong turn. However, you should never over tighten the spark plugs.

Step 6 - Reattach Wires

Gently reattach each wire into the specific spark plug with your fingertips. It is vitally important to put the wires back in the right sequence on engines with multiple cylinders. If you do not, the bike will break down a short time after it has started, if you can manage to get it to start at all.