Polaris Sportsman 500 Spark Plug Size

Ever had your trusty Polaris Sportsman 500 sputter, cough, or refuse to start right when you’re geared up for a day on the trails? We’ve all been there. That sinking feeling often points to one of the smallest, yet most critical, parts of your engine: the spark plug.

You probably know a bad plug can cause problems, but getting the replacement right is just as important. We promise this guide will eliminate all the guesswork. You’ll get the exact information you need to find the correct polaris sportsman 500 spark plug size and install it with the confidence of a seasoned mechanic.

In this comprehensive guide from the FatBoysOffroad team, we’ll walk you through identifying the right plug, the tools you’ll need, a step-by-step replacement process, and even how to diagnose engine health just by looking at your old plug. Let’s get that ATV running like new again.

Why the Correct Spark Plug Size is Non-Negotiable for Your Sportsman 500

It’s easy to think “a spark plug is a spark plug,” but for your ATV’s engine, that’s a dangerous oversimplification. The term “size” doesn’t just refer to the socket you use to remove it; it’s a combination of three critical factors: thread size, reach, and heat range.

Getting any of these wrong can lead to a world of hurt for your engine. This is where our polaris sportsman 500 spark plug size guide becomes your best friend, preventing costly mistakes.

The Critical Trio: Thread, Reach, and Heat Range

Thread Size & Pitch: This is the diameter of the threaded part of the plug. The Sportsman 500, like most modern engines, has a specific size. Using the wrong one can strip the threads in your engine’s cylinder head—a very expensive repair.
Reach: This is the length of the threaded portion. A plug that’s too short won’t position the electrode correctly in the combustion chamber, leading to poor performance and fouling. A plug that’s too long can actually hit the piston, causing catastrophic engine damage.
Heat Range: This refers to the plug’s ability to dissipate heat. A “hot” plug retains more heat, while a “cold” plug dissipates it faster. The wrong heat range can cause pre-ignition (knock) or carbon fouling, both of which rob you of power and efficiency.

The clear benefits of polaris sportsman 500 spark plug size accuracy are better performance, easier starting, improved fuel economy, and most importantly, engine longevity. It’s a simple piece of maintenance that pays huge dividends.

The Official Polaris Sportsman 500 Spark Plug Size and Top Recommendations

Alright, let’s get down to brass tacks. For the vast majority of Polaris Sportsman 500 models, especially the popular H.O. (High Output) versions from the early 2000s onward, the standard OEM recommended spark plug is the NGK BKR6E.

Let’s break down what that part number means and give you some upgrade options.

Decoding the Part Number

The manufacturer-specified plug is your safest bet. Here are the key specs for the NGK BKR6E:

Thread Diameter: 14mm
Thread Reach: 19mm (3/4″)
Hex Size (Socket Size): 16mm or 5/8″
Spark Gap: Typically 0.035″ (0.9mm), but always verify with your owner’s manual or a service manual.

This is the starting point for your search. Always double-check your specific year and model, as minor variations can exist, but the BKR6E is the go-to for countless Sportsman 500 owners.

Spark Plug Upgrade Options: Copper vs. Iridium

You have choices beyond the standard copper plug. Here’s a quick rundown:

Standard Copper (NGK BKR6E): The workhorse. It’s affordable and provides excellent performance. The downside is a shorter lifespan; you should plan on changing it every 50-100 hours of use.
Iridium (NGK BKR6EIX): The premium choice. Iridium plugs have a fine-wire center electrode that provides a more focused, consistent spark. They last significantly longer (2-3 times longer than copper) and offer slightly better throttle response and cold-start performance.

For a more eco-friendly polaris sportsman 500 spark plug size choice, an iridium plug is a great option. Its improved efficiency and longevity mean better fuel burn and less waste over the life of your ATV.

Essential Tools and Prep for Your Spark Plug Swap

Having the right tools ready makes this a quick 15-minute job instead of a frustrating afternoon. Here are some polaris sportsman 500 spark plug size best practices for getting prepped.

Your Tool Checklist:

Safety First: Safety glasses are a must.
Spark Plug Socket: A dedicated 5/8″ (or 16mm) spark plug socket is essential. It has a rubber insert that grips the plug, making it easy to pull out and install without damage.
Socket Wrench and Extension: A 3/8″ drive ratchet with a 6-inch extension will give you the reach and leverage you need.
Compressed Air or a Brush: To clean the area around the spark plug before you remove it. You don’t want dirt falling into your engine.
Torque Wrench: This is highly recommended. Over-tightening a spark plug can damage the cylinder head, while under-tightening can cause it to back out. The correct torque is usually around 18-22 ft-lbs, but check your manual.
Spark Plug Gapper Tool: A simple feeler gauge or gapper tool to ensure the gap on the new plug is set to your machine’s specifications.
Dielectric Grease: A small dab inside the spark plug boot prevents corrosion and makes future removal easier.

How to Change Your Polaris Sportsman 500 Spark Plug: A Step-by-Step Guide

Ready to get your hands dirty? This is the core of our how to polaris sportsman 500 spark plug size guide. Follow these steps carefully for a flawless installation.

Step 1: Ensure the Engine is Cool

Never work on a hot engine. Metal expands when hot, which can make removing the spark plug difficult and increase the risk of stripping threads. Let the ATV sit for at least an hour.

Step 2: Locate the Spark Plug

On most Sportsman 500s, the spark plug is on the left side of the engine (as you’re sitting on it). You’ll see a thick black wire, the spark plug wire, connected to the top of the engine. The plug is underneath that boot.

Step 3: Clean the Area

This is a critical step many people skip. Use your compressed air or a stiff brush to clean all the dirt, mud, and debris from around the base of the spark plug boot. This prevents junk from falling into the combustion chamber when you remove the plug.

Step 4: Remove the Spark Plug Boot

Grip the boot firmly—not the wire itself—and twist it slightly as you pull straight up. It might be on there snugly, but a gentle twisting pull should pop it right off.

Step 5: Remove the Old Spark Plug

Place your 5/8″ spark plug socket and extension over the plug. Turn your ratchet counter-clockwise to loosen it. It should break free with a bit of force and then spin out easily. Use the socket to lift the old plug out of the engine.

Step 6: Prepare the New Spark Plug

Before installing the new plug, check the gap. Use your gapper tool to verify it’s set to the spec in your owner’s manual (usually 0.035″). Most NGK plugs come pre-gapped, but it’s a cardinal rule to always check. A quick tip: apply a very thin coat of anti-seize compound to the threads of the new plug, being careful not to get any on the electrode.

Step 7: Install the New Spark Plug

Carefully lower the new plug into the hole using your spark plug socket. Start threading it by hand. This is crucial to prevent cross-threading. It should screw in smoothly for several turns. Once it’s finger-tight, use your torque wrench to tighten it to the specified torque. If you don’t have a torque wrench, a general rule is to tighten it until the crush washer is seated, then give it another 1/4 to 1/2 turn.

Step 8: Reinstall the Boot

Apply a small amount of dielectric grease to the inside of the spark plug boot. This ensures a good electrical connection and prevents moisture intrusion. Push the boot firmly back onto the top of the new spark plug until you feel or hear it “click” into place.

Reading the Old Plug: What Your Sportsman’s Engine is Telling You

Don’t just toss that old plug! It’s a window into your engine’s health. This is an advanced part of any polaris sportsman 500 spark plug size care guide. Look at the firing end:

Light Tan or Grayish-Brown: Perfect! This indicates a healthy engine with a proper air/fuel mixture.
Black and Sooty (Dry): Your engine is running too rich (too much fuel, not enough air). This could be a dirty air filter or a carburetor issue.
Oily and Black (Wet): This is more serious. It suggests oil is getting into the combustion chamber, possibly from worn piston rings or valve seals.
White and Blistered: Your engine is running too lean (too much air, not enough fuel) or overheating. This is a dangerous condition that can burn a hole in your piston. Check for vacuum leaks or fuel delivery problems immediately.

Common Problems and Troubleshooting Your Spark Plug Replacement

Even a simple job can have hiccups. Here are some common problems with polaris sportsman 500 spark plug size and maintenance, along with our pro tips.

Problem: The Spark Plug is Seized and Won’t Come Out

Solution: Stop! Do not apply more force. Spray a quality penetrating oil (like PB B’laster) around the base of the plug and let it soak for 30 minutes. Try gently tightening it a tiny bit, then loosening it. Rocking it back and forth can help break it free. If it still won’t budge, it’s time to take it to a professional to avoid breaking it off in the head.

Problem: The Engine Still Runs Rough After a New Plug

Solution: First, double-check that the spark plug boot is fully seated. If it is, the issue may not have been the plug. Check for a weak spark (could be a bad coil or wire), fuel delivery issues (clogged filter or carb), or a dirty air filter.

Problem: I Dropped the New Spark Plug

Solution: Inspect it very carefully. A drop can crack the ceramic insulator (the white part) or, more commonly, close the spark gap. If the ceramic is cracked, do not use it. If the gap is just closed, you can carefully re-gap it with your tool. When in doubt, it’s best to use a new one.

Frequently Asked Questions About the Polaris Sportsman 500 Spark Plug Size

What is the socket size for a Polaris Sportsman 500 spark plug?

The correct socket size is 5/8 inch (or 16mm). It is highly recommended to use a dedicated spark plug socket with a rubber insert to protect the plug during installation and removal.

How often should I change the spark plug on my Sportsman 500?

For a standard copper plug (like the NGK BKR6E), a good rule of thumb is every 50-100 hours of ride time or at least once a year. If you use a premium iridium plug (NGK BKR6EIX), you can extend that interval to 200-300 hours.

What is the correct spark plug gap for a Polaris Sportsman 500?

The typical spark plug gap is 0.035 inches (0.9mm). However, you should always confirm this specification in your ATV’s owner’s or service manual for your specific model year, as slight variations can occur.

Can I use a Champion or Autolite spark plug instead of NGK?

Yes, other brands offer equivalent plugs. You will need to use a cross-reference chart to find the correct part number. For example, a common Champion equivalent is the RC12YC. However, in our experience at the shop, NGK plugs consistently provide the best performance and reliability in Polaris engines.

Replacing your spark plug is one of the easiest and most rewarding pieces of maintenance you can perform on your Polaris Sportsman 500. It’s a quick job that directly impacts your ATV’s performance, reliability, and health. By following this guide, you have all the knowledge and polaris sportsman 500 spark plug size tips you need to tackle the job with confidence.

Now, grab your tools, get that new plug installed, and get back out on the trails where you belong. Ride safe and have fun!

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Thomas Corle

Founder & Automobile expert at FatBoysOffroad

Automobile expert and off-road enthusiast, sharing in-depth knowledge of vehicles, gear, and adventures. Helping readers make smart decisions and enjoy the thrill of off-roading safely and confidently.