If you own a Honda GCV160 engine—whether it’s powering your lawn mower, pressure washer, or generator—you’ve likely experienced that frustrating moment when the engine starts bogging down under load. It sputters, loses power, and just won’t run smoothly. While there are several potential causes for this issue, one of the most common and often overlooked culprits is a worn or incorrect spark plug.
The spark plug is the heart of your engine’s ignition system. It delivers the electric spark that ignites the air-fuel mixture in the combustion chamber, creating the power stroke that keeps your equipment running. When that spark weakens or fails to ignite properly, performance suffers dramatically. In the case of the GCV160—a reliable, single-cylinder, overhead cam engine found in countless residential tools—using the right replacement spark plug isn’t just a maintenance task; it’s a critical performance decision.
This guide is designed to help you cut through the confusion and make an informed choice. Whether you’re a weekend warrior tackling yard work or a DIY enthusiast maintaining multiple small engines, understanding what makes a spark plug “right” for your GCV160 can mean the difference between smooth operation and constant frustration. We’ll walk you through everything from technical specifications to real-world performance, budget considerations, and expert tips to ensure you get the best possible replacement—not just the cheapest or most popular one.
You’ll learn how to identify the exact spark plug your engine needs, understand why certain types outperform others, avoid common pitfalls, and even save money without sacrificing quality. By the end of this guide, you’ll have the confidence to diagnose spark plug issues, choose the optimal replacement, and keep your GCV160 running strong for years to come. The market is flooded with options—from OEM Honda plugs to aftermarket brands like NGK, Champion, and Autolite—but not all are created equal. Let’s dive in and find the perfect match for your engine.
What to Look for When Buying Buying Guide
1. Correct Heat Range
The heat range of a spark plug refers to its ability to dissipate heat from the combustion chamber. If the plug runs too hot, it can cause pre-ignition or detonation, damaging the engine. If it runs too cold, carbon deposits build up, leading to fouling and misfires. For the Honda GCV160, the correct heat range is critical because this engine operates under variable loads—light idling one moment, full throttle the next. Using a plug with the wrong heat range is a leading cause of bogging, especially under heavy load.
Honda specifies a specific heat range for the GCV160, typically corresponding to a “cold” or medium-cold plug. Most OEM and high-quality aftermarket replacements will match this specification. Look for plugs labeled with heat ranges like “CR5” or “BP6ES” (depending on the brand), which are designed for small engines with high compression and frequent load changes. Avoid plugs that are too hot—they may seem to work initially but will cause long-term damage.
2. Proper Thread Size and Reach
Spark plugs must fit precisely into the cylinder head. The GCV160 uses a 14mm thread diameter with a 19mm (3/4 inch) reach—meaning the threaded portion extends 19mm into the combustion chamber. Using a plug with incorrect thread length can lead to serious problems. A plug that’s too short won’t reach the combustion chamber properly, causing weak sparks and poor combustion. One that’s too long can protrude into the chamber, risking contact with the piston—a catastrophic failure.
Additionally, the thread pitch must match. Most GCV160 engines use a standard 1.25mm pitch. While many modern plugs are designed to universal standards, it’s essential to verify compatibility. Always check the spark plug’s specifications against your engine model. Misaligned threads can strip the cylinder head, leading to expensive repairs.
3. Electrode Material and Design
The material and design of the spark plug’s electrodes directly impact ignition efficiency, durability, and resistance to fouling. Traditional copper-core plugs are common and affordable but wear out faster. Platinum and iridium plugs, while more expensive, offer superior longevity and consistent spark performance.
For the GCV160, iridium plugs are increasingly recommended due to their fine-wire center electrode, which requires less voltage to fire and maintains a sharp edge over time. This results in a stronger, more reliable spark—especially important when the engine is under load and bogging is most likely to occur. Platinum plugs are a good middle ground, offering better performance than copper without the premium price of iridium.
The electrode gap is also crucial. The GCV160 typically requires a gap of 0.028 to 0.031 inches (0.7–0.8mm). A gap that’s too wide can cause misfires under load; too narrow, and the spark may not be strong enough to ignite the mixture efficiently. Always check and adjust the gap before installation.
4. OEM vs. Aftermarket Compatibility
Honda recommends specific OEM spark plugs for the GCV160, such as the Honda 98079-5532A (NGK CR5HS) or 98079-55347 (Champion RCJ6Y). These are engineered to exact specifications and undergo rigorous testing. However, high-quality aftermarket plugs from reputable brands like NGK, Champion, and Autolite can perform just as well—or better—than OEM parts, often at a lower price.
The key is to ensure the aftermarket plug is a direct replacement, not just a “fits most” option. Look for plugs that are listed as compatible with the GCV160 in the manufacturer’s application guide. Avoid cheap, no-name brands that may use inferior materials or inconsistent manufacturing processes. A poorly made plug can foul quickly, cause hard starting, and contribute to bogging.
5. Resistance to Fouling and Deposits
Small engines like the GCV160 are prone to spark plug fouling due to short run times, rich fuel mixtures, and low operating temperatures. A fouled plug—covered in carbon, oil, or fuel deposits—cannot deliver a strong spark, leading to misfires and bogging.
Look for spark plugs with features that resist fouling, such as a projected nose design, which positions the electrode closer to the flame front for better ignition. Some plugs also include anti-fouling coatings or specialized electrode geometries that promote cleaner combustion. Iridium and platinum plugs generally resist fouling better than copper due to their higher melting points and smoother surfaces.
If your engine frequently bogs under load, consider whether the plug is fouling prematurely. Inspect it regularly—clean or replace it if you see black, sooty deposits (indicating a rich mixture) or oily residue (suggesting oil burning).
6. Voltage Requirements and Ignition System Compatibility
The GCV160 uses a magneto ignition system, which generates high-voltage pulses to fire the spark plug. Not all plugs are designed to work efficiently with this type of system. Some aftermarket plugs, especially those with very fine electrodes, may require more voltage to fire than the magneto can consistently provide—leading to weak sparks and misfires.
Choose plugs that are optimized for low-voltage ignition systems. NGK’s “HS” series (like the CR5HS) and Champion’s “RCJ” series are specifically designed for small engines with magneto ignitions. These plugs have electrode configurations that ensure reliable spark generation even under marginal voltage conditions.
Avoid plugs labeled for automotive or high-performance applications unless explicitly rated for small engines. They may not perform well in the GCV160’s unique ignition environment.
7. Ease of Installation and Maintenance
While spark plug replacement is generally straightforward, some designs make the process easier. Look for plugs with a gasket seat (as opposed to a tapered seat) if your engine requires it—the GCV160 typically uses a gasketed plug. This ensures a proper seal and prevents leaks.
Also consider the plug’s hex size. Most GCV160 engines use a 5/8-inch or 13/16-inch hex, which fits standard spark plug sockets. Avoid plugs with non-standard sizes that require special tools.
Finally, think about long-term maintenance. Some plugs are designed for extended service intervals—up to 100 hours or more—while others may need replacement every 25–50 hours. If you use your equipment frequently, investing in a longer-lasting plug can save time and money.
8. Warranty and Brand Support
While spark plugs are consumable parts, reputable manufacturers often back their products with warranties or guarantees. NGK, for example, offers a limited warranty against defects in materials and workmanship. Champion and Autolite also provide solid customer support and clear replacement guidelines.
When buying, check the packaging for warranty information and ensure the seller is authorized. Avoid purchasing from unknown online sellers offering suspiciously low prices—these may be counterfeit or refurbished plugs that fail prematurely.
A good warranty not only protects your investment but also reflects the manufacturer’s confidence in their product. For a component as critical as the spark plug, that confidence matters.
Different Types of Buying Guide
Common Buying Mistakes to Avoid
❌ Mistake: Choosing the Wrong Heat Range
Why it’s bad: A plug that’s too hot can cause pre-ignition, leading to engine knocking, overheating, and potential piston damage. One that’s too cold won’t burn off deposits, resulting in fouling and misfires—especially under load when the GCV160 is most vulnerable to bogging.
What to do instead: Always match the heat range specified by Honda. Cross-check the part number in your owner’s manual or on the existing plug. When in doubt, consult a parts diagram or contact a Honda dealer.
❌ Mistake: Ignoring the Electrode Gap
Why it’s bad: An incorrect gap affects spark strength and timing. A gap that’s too wide may not fire reliably under load, causing bogging. Too narrow, and the spark may not ignite the mixture efficiently, reducing power and increasing emissions.
What to do instead: Use a feeler gauge to check and adjust the gap to 0.028–0.031 inches before installation. Never assume the plug comes pre-gapped correctly—especially with aftermarket brands.
❌ Mistake: Buying the Cheapest Plug Available
Why it’s bad: Low-cost, no-name plugs often use inferior materials and inconsistent manufacturing. They may foul quickly, fail under load, or even damage the ignition system due to poor conductivity.
What to do instead: Invest in a reputable brand like NGK, Champion, or Autolite. The small price difference is worth the reliability and performance gain—especially if bogging is already an issue.
❌ Mistake: Using Automotive Spark Plugs
Why it’s bad: Automotive plugs are designed for high-voltage coil-on-plug systems, not the low-voltage magneto in the GCV160. They may require more voltage to fire, leading to weak sparks and misfires.
What to do instead: Only use plugs specifically rated for small engines. Look for designations like “HS” (NGK) or “RCJ” (Champion), which indicate compatibility with magneto systems.
❌ Mistake: Overlooking Installation Torque
Why it’s bad: Over-tightening can strip the threads in the aluminum cylinder head. Under-tightening can cause leaks, overheating, and poor heat transfer.
What to do instead: Use a torque wrench set to 13–15 ft-lbs (18–20 Nm) for gasketed plugs. If you don’t have a torque wrench, hand-tighten plus 1/4 to 1/2 turn—never force it.
❌ Mistake: Reusing Old Plugs Without Inspection
Why it’s bad: Even if a plug looks clean, internal wear or micro-cracks can affect performance. Reusing a worn plug contributes to bogging and hard starting.
What to do instead: Inspect the plug for signs of wear, fouling, or damage. If in doubt, replace it. Spark plugs are inexpensive compared to the cost of engine trouble.
❌ Mistake: Not Considering Usage Patterns
Why it’s bad: A plug suitable for occasional mowing may not hold up under constant pressure washing or generator use. Choosing the wrong type leads to premature failure.
What to do instead: Match the plug to your usage. Heavy users should consider iridium or double-platinum plugs for longer life and better performance under load.
Budget Guidelines: How Much Should You Spend?
– Entry-Level ($2–$5): Copper-core plugs from brands like Autolite or generic equivalents. Best for occasional use or as a temporary fix. Expect to replace every 25–50 hours. May contribute to bogging under heavy load due to weaker spark and faster wear.
– Mid-Range ($6–$10): Platinum or high-quality copper plugs from NGK or Champion. Ideal for most homeowners. Offer better durability and more consistent performance. A solid choice if you use your equipment weekly and want reliable operation without overspending.
– Premium ($10–$15): Iridium plugs designed for small engines. Excellent for frequent use, heavy loads, or engines that already exhibit bogging. Provide stronger sparks, resist fouling, and last 2–3 times longer than copper. Highly recommended for pressure washers and generators.
– Luxury ($15+): Double iridium or platinum plugs with advanced electrode designs. Best for enthusiasts, professionals, or modified engines. Offer maximum longevity and peak performance but may be overkill for light residential use.
Expert Tips for Getting the Best Deal
– Buy in Bulk: If you maintain multiple small engines, consider buying spark plugs in packs of 3–6. Many retailers offer discounts for multi-packs, and you’ll always have a spare on hand.
– Check Seasonal Sales: Lawn and garden retailers often run promotions in early spring and late fall. Stock up during these periods for the best prices.
– Use Manufacturer Rebates: NGK and Champion occasionally offer mail-in rebates on spark plugs. Check their websites before purchasing.
– Buy from Authorized Retailers: Avoid counterfeit plugs by purchasing from trusted sources like Home Depot, Lowe’s, Amazon (sold by the brand), or local small engine shops.
– Read Reviews Carefully: Look for reviews that mention GCV160 compatibility and performance under load. Real user feedback is more valuable than marketing claims.
– Inspect Before Installing: Even new plugs can be damaged in shipping. Check for cracks, bent electrodes, or incorrect gaps before installation.
– Keep Records: Note the date and hours of operation when you install a new plug. This helps you track wear and plan future replacements.
– Combine with Other Maintenance: Replace the spark plug when servicing the air filter, fuel filter, or carburetor. This ensures all components are working optimally together.
Frequently Asked Questions
Q: Why is my GCV160 bogging down under load?
A: Bogging under load is often caused by a weak spark, which can result from a worn, fouled, or incorrect spark plug. Other causes include a dirty carburetor, clogged air filter, or fuel delivery issues—but the spark plug should be one of the first things you check.
Q: Can I use a different spark plug if the exact OEM isn’t available?
A: Yes, as long as the replacement has the same thread size, reach, heat range, and electrode gap. NGK CR5HS, Champion RCJ6Y, and Autolite 25 are all direct replacements for the Honda 98079-5532A.
Q: How often should I replace the spark plug in my GCV160?
A: Honda recommends replacement every 100 hours of operation or annually, whichever comes first. However, if you notice hard starting, rough idle, or bogging, inspect the plug sooner.
Q: Should I gap the spark plug before installing?
A: Yes. Even if the plug is labeled “pre-gapped,” always verify the gap with a feeler gauge. The correct gap for the GCV160 is 0.028–0.031 inches.
Q: Can a bad spark plug damage my engine?
A: Indirectly, yes. A misfiring plug can cause unburned fuel to enter the exhaust, potentially damaging the catalytic converter (if equipped). It can also lead to overheating and poor combustion, reducing engine life.
Q: Is it worth upgrading to an iridium plug?
A: Absolutely, especially if your engine bogs under load. Iridium plugs provide a stronger, more consistent spark, resist fouling, and last significantly longer—making them a cost-effective upgrade.
Q: Can I clean and reuse a fouled spark plug?
A: You can clean a lightly fouled plug with a wire brush or spark plug cleaner, but it’s often better to replace it. Cleaning doesn’t restore worn electrodes, and the plug may still underperform.
Q: Does the spark plug affect fuel efficiency?
A: Yes. A properly functioning plug ensures complete combustion, which improves fuel efficiency and reduces emissions. A weak or fouled plug wastes fuel and reduces power.
Q: What’s the difference between CR5HS and CR6HS?
A: The number indicates the heat range. CR5HS is colder than CR6HS. The GCV160 typically uses the CR5HS (or equivalent). Using a CR6HS may run too hot and cause pre-ignition.
Q: Can I install the spark plug without a torque wrench?
A: Yes, but be careful. Hand-tighten until the gasket seats, then turn another 1/4 to 1/2 turn. Over-tightening is a common cause of thread damage.
Our Final Recommendations
– Best for Budget-Conscious Buyers: NGK CR5HS (Copper) – Reliable, affordable, and widely available. A great OEM-equivalent option for light to moderate use.
– Best Overall Value: Champion RCJ6Y (Platinum) – Offers excellent performance and durability at a mid-range price. Ideal for most homeowners.
– Best Premium Option: NGK CR5HS-11 (Iridium) – Features a fine-wire iridium center electrode for superior spark strength and longevity. Perfect for engines that bog under load.
– Best for Beginners: Autolite 25 (Copper) – Easy to find, simple to install, and budget-friendly. Great for first-time users learning basic maintenance.
– Best for Advanced Users: NGK CR5HSGP (Double Iridium) – Designed for maximum performance and extended service life. Best for professionals or heavily modified engines.
Conclusion: Making the Right Choice
Choosing the right spark plug for your Honda GCV160 isn’t just about swapping out a worn part—it’s about restoring optimal performance, preventing future issues, and ensuring your equipment runs reliably when you need it most. Bogging under load is often a symptom of ignition weakness, and the spark plug is the first line of defense.
Throughout this guide, we’ve covered the critical factors that influence spark plug performance: heat range, thread compatibility, electrode material, and brand reliability. We’ve compared different types, highlighted common mistakes, and provided budget-friendly options for every user. Whether you’re a casual weekend gardener or a full-time equipment operator, there’s a spark plug that fits your needs and your engine’s demands.
Remember, the cheapest option isn’t always the best value. Investing in a quality plug—especially one made from iridium or platinum—can save you time, frustration, and money in the long run. It ensures stronger sparks, better combustion, and smoother operation under load. And when your GCV160 is powering through thick grass or driving a high-pressure spray, that reliability makes all the difference.
Before you make your final decision, take a moment to assess your usage patterns, inspect your current plug, and consult your owner’s manual. Then choose a replacement that matches your engine’s specifications and your performance expectations. With the right spark plug, your GCV160 will start easier, run smoother, and deliver the power you count on—load after load.
Don’t let a simple component like a spark plug hold back your equipment’s potential. Make the switch today, and feel the difference in every cut, wash, and run.