Choosing the Right Spark Plugs for Your 1982-1986 Arctic Cat Cheetah 340
Get reliable starts and smooth performance from your vintage Cheetah 340 with the correct set of spark plugs.
- The recommended aftermarket spark plug is the NGK B8ES.
- Always check and set the spark plug gap to 0.8mm (0.032") before installation.
- Replace spark plugs at the start of every season for reliable operation.
- Visually inspect old plugs when you remove them; their condition can tell you about your engine's health.
Symptoms of Failing Spark Plugs
When your spark plugs are worn out or fouled, your Cheetah 340 will let you know. Because the engine has two cylinders, a problem with one plug can make the sled run rough, while a problem with both can prevent it from starting at all. Look for these common signs:
- Hard Starting or No Start: Weak or non-existent spark makes it difficult or impossible to get the engine to fire up.
- Rough Idle: The engine may shake or sound uneven at idle if a plug isn't firing consistently.
- Misfiring: You might hear a popping or sputtering sound from the engine, especially under acceleration. The sled may feel like it's losing power and then suddenly getting it back.
- Loss of Power: Worn plugs can't ignite the fuel mixture efficiently, leading to a noticeable drop in performance and top speed.
- Increased Fuel Consumption: An incomplete burn caused by a bad spark plug means you'll be burning through more fuel than usual.
Reading the Plugs
After removing an old spark plug, look at its tip. A light brown or tan color means the engine is running well. A black, oily, or wet plug indicates fouling, which could be from an incorrect fuel mixture or the wrong type of plug. A white or blistered insulator means the plug is running too hot, which can cause serious engine damage.
Choosing the Right Aftermarket Spark Plug
For a vintage machine like the 1982-1986 Cheetah 340, you don't need to hunt down expensive original parts. High-quality aftermarket spark plugs are readily available, affordable, and perform just as well as—or better than—the originals. The most important factors are choosing a reputable brand and the correct part number.
Brand Tiers
- Tier 1 (Recommended): NGK is the most widely recommended and used brand for these snowmobiles. The standard NGK B8ES is the correct plug for most conditions and is considered the go-to choice. It offers excellent performance and reliability at a very low cost.
- Tier 2 (Alternative): Champion is another established brand that offers compatible plugs. While not as commonly referenced for this specific sled as NGK, they are a reliable alternative if NGK plugs are unavailable.
- Iridium Option: NGK offers an iridium version, the BR8EIX. Iridium plugs last longer and can provide a more consistent spark. However, for a vintage, fan-cooled engine like the Cheetah 340, the performance benefits are minimal and may not justify the higher cost compared to standard copper plugs.
Heat Range is Critical
Spark plugs come in different "heat ranges." For NGK plugs, a lower number is hotter (resists fouling) and a higher number is colder (dissipates heat faster for high-RPM use). The B8ES is the standard, recommended heat range. Only consider a colder B9ES if you are doing long, high-speed runs and find the B8ES plugs are showing signs of overheating. For general trail riding, stick with the B8ES.
| Part | Brand | Part Number | Notes |
|---|---|---|---|
| Standard Spark Plug | NGK | B8ES | Recommended for all-around use. Excellent value and performance. |
| Iridium Spark Plug | NGK | BR8EIX | Long-life upgrade. Not essential but works well. |
| Alternative Plug | Champion | N4C / RN4C | Cross-references to the NGK B8ES. A solid second choice. |
Frequently Asked Questions
What is the correct spark plug gap for the Cheetah 340?
The correct spark plug gap is 0.8mm (or 0.032 inches). Always check the gap with a feeler gauge before installing new plugs, as they can be knocked out of spec during shipping.
How often should I change the spark plugs?
For a two-stroke engine, it's good practice to check your plugs frequently and replace them at the beginning of each season or every 50-100 hours of use, whichever comes first. Since they are inexpensive, it's cheap insurance against being stranded with a non-starting sled.
Do I need resistor plugs (BR8ES vs. B8ES)?
A resistor plug (like the BR8ES) is designed to reduce radio frequency interference (RFI) that can affect electronic devices. The 1982-1986 Cheetah 340 has minimal electronics, so a standard, non-resistor B8ES plug is perfectly fine. However, a resistor plug will also work without any issues if that's all that is available.
Should I use anti-seize on the spark plug threads?
NGK, the primary manufacturer, recommends NOT using anti-seize on their plugs. Their plugs have a special plating that prevents seizing. Applying anti-seize can act as a lubricant, causing you to over-torque the plug, which can damage the threads in the aluminum cylinder head.
Technical Specifications
Recommended Plug: NGK B8ES Thread Diameter: 14mm Thread Reach: 19mm Wrench Size: 21mm (13/16") Gap: 0.8mm (0.032")
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Arctic Cat Cheetah 340: