How to Change Spark Plug Suzuki LT-Z250 (2004-2009)

  • This ‘how to change spark plug’ instruction guide specifically applies to 2004-2009 Suzuki LT-Z250 Quadsport ATVs.

A spark plug is a device that fits into the cylinder head for firing the explosive mixture in an internal combustion engine. Spark plugs are responsible for igniting the air/fuel mixture and creating a controlled explosion. This violent expansion of energy is what makes your engine produce power into motion. Spark plugs typically last anywhere between 1.5 and 2.25 years or 20,000 to 30,000 miles. In some cases a spark plug can fail prematurely as a result of using a plug with an incorrect heat range or because of incorrect spark plug gap. That said, most spark plugs go bad because of improper torque.

To prevent engine damage or poor engine performance it is important to inspect your all-terrain vehicle’s spark plug on a regular basis and change it if worn or damaged. Changing a spark plug is more than just the substitution of one plug for another. You must swap a plug with a correct heat range. Before you switch a spark plug inspect it for carbon deposits and check the condition of the electrode. You must also measure the spark plug gap and adjust it to the correct thickness. Most importantly, you must torque the spark plug appropriately to avoid cylinder head damage.

How to Change Spark Plug

How often should you change the spark plug?

The manufacturer recommends to inspect the spark plug every 6 months and replace it every 18 months. Examine the plug for insulator damage and wear. Replace plug if needed.

Spark Plug Removal

How to replace spark plug?

To take off the spark plug, first detach the spark plug cap (1) as seen in image. Use a spark plug wrench to extract the plug from the cylinder head.




Spark Plug Heat Range

Spark plug heat range refers to the range in which the spark plug works well thermally. NGK spark plugs use a number to indicate heat range. A low number designate it as a hotter type plug whereas a higher number indicates a colder plug.

Once you pull out the spark plug, check the spark plug heat range. Carefully view the electrode’s color. If the electrode appears wet or dark in color, switch the spark plug with a hotter type. Use a colder type spark plug if the electrode appears white or glazed. Refer to the chart below for factory recommended plug type. 

Spark Plug Type

Factory specifications require the use of NGK or DENSO brand spark plugs. Spark plug type or model number.

  • Standard: NGK DR7EA or DENSO X22ESR-U
  • Colder Type: NGK DR8EA or X24ESR-U
What type and brand spark plug to use on Suzuki LT-Z 250?
Factory recommended spark plug type.

Spark Plug Gap

What is the spark plug gap for Suzuki LTZ250

Spark plug gap refers to the space between the spark plug center electrode and ground electrode. The space between the electrodes is where the electric arc ignites fuel in a combustion chamber.

Measure the existing gap thickness with a feeler gauge. If the gap is not within factory specifications, adjust the gap as needed.

Spark plug gap factory spec: 0.6 0.7 mm (0.024 0.028 in)

Spark Plug Inspection

Inspect the condition of the spark plug’s electrode. Change the plug with a new one if the electrode is excessively worn or appears to be burnt. Also, switch the old plug with a new spark plug if the treads are damaged or if the insulator is broken.

Use caution when changing the plug. Make sure the thread size and reach isn’t too short. If the reach is short carbon deposits will build on the screw portion of the spark plug hole and it could result in engine damage.

Spark Plug Installation

Install the spark plug into the hole on the cylinder head using your fingers to avoid cross threading. Ensure the spark plug is seated properly and finger tighten it. Then use the spark plug wrench to torque the spark plug to factory specifications. Don’t forget to re-attach the spark plug cap. 

Spark plug factory spec: 18 N•m (1.8 kgf-m, 13.0 lb-ft)

Richard Potter

Hi, I'm Richard, small engine mechanic with a combined 20 years experience in small engine service and repair. I fix everything from all-terrain vehicles, dirt bikes, scooters, and, generators, both gas, and diesel. Have a mechanical issue? Submit a detailed description of the problem in the comment box below. I will answer it ASAP.

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