We Tested 7 Best Spark Plugs For Generators in 2025

When the power goes out, the last thing you want is your generator sputtering to life. Having run portable generators for years—both for remote worksites and emergency home backup—I’ve learned that reliable starting power often comes down to one tiny component: the spark plug. A quality spark plug ensures quick ignition, better fuel efficiency, and keeps carbon buildup minimal. To help you maintain your backup power system, we’ve put the leading replacement spark plugs through their paces to find the absolute best spark plugs for generators currently available. This guide reviews compatibility, performance, and overall value, so you can easily choose the right part for your equipment, whether you’re running a small Honda GX or a large Predator engine.

IMAGE	PRODUCT NAME	AMAZON LINK
	YAMAKATO Spark Plug for NGK BPR6ES BP6ES TORCH F6RTC F6TC…	View on Amazon
	FLYPIG F7TC Standard Powersports Spark Plug For GCV160…	View on Amazon
	PK2 TORCH F7TC Spark Plug Replace for NGK 3785 BP7ES…	View on Amazon
	GREPSPUD 2pcs F7TC Spark Plugs GX120 GX160 GX200 GX240…	View on Amazon
	TORCH F6TC Spark Plug 131-047 Replace for NGK BP6ES, for…	View on Amazon
	GREPSPUD 4pcs F7TC Spark Plugs GX120 GX160 GX200 GX240…	View on Amazon
	F7TC Spark Plug Fit for Harbor Freight Predator 6.5HP…	View on Amazon

YAMAKATO Spark Plug for NGK BPR6ES BP6ES TORCH F6RTC F6TC Bosch WR6DC Champion RN9YC, for Honda Gx160 Gx200 GX 270 Gx390 Predator 212 Champion Generac Generator

This YAMAKATO package is designed for the generator owner who needs incredible versatility and value. It’s an OEM-quality replacement built to cross-reference with a massive list of popular small engine plugs, making it a truly universal choice for workshops and garages. The robust compatibility ensures it works perfectly across major brands like Honda, Generac, and Predator engines. If you manage multiple pieces of small equipment, stocking this reliable 3-pack is a smart, cost-effective maintenance strategy.

Key features that stand out:

• Massive Engine Compatibility: Fits practically every common 4-stroke engine size (from 120cc up to 459cc).
• Excellent Value Pack: Comes in a 3-piece set, plus a roll of free Teflon Tape for convenience.
• Common Cross-Reference: Directly replaces popular plugs like NGK BPR6ES and Champion RN9YC.

Pros:
– Offers superior value with three plugs per purchase.
– The included thread sealant (Teflon tape) is a thoughtful addition.
– Guaranteed compatibility with popular Predator 212 and Honda GX series engines.

Cons:
– While high quality, it is not a premium material plug (like iridium).

Best for: Generator owners seeking a bulk, cross-compatible replacement that covers nearly all standard small engines.

Expert Opinion: This set is the definition of a practical maintenance purchase. Its broad compatibility list, especially covering the ubiquitous Honda GX and Predator clones, makes it a reliable shelf stocker for emergency replacements.

FLYPIG F7TC Standard Powersports Spark Plug For GCV160 GCV190 GX120 GX160 GX200 GX240 GX270 GX340 GX390 Generator Lawnmower Tractor Rototiller Water Pump Go Kart Mini Bike Tillage Polishing Machine

The FLYPIG F7TC plug caters specifically to users looking for performance enhancements over standard factory plugs. Designed to handle intense operating conditions, this plug utilizes a slightly colder heat range than some stock options, which is beneficial if you frequently run your generator or equipment under heavy loads for extended periods. It promises reliable starting and improved responsiveness across a wide array of generator and powersports applications.

Key features that stand out:

• Wider Heat Range Operation: Engineered to perform effectively under diverse temperatures and loads.
• Designed for Performance: Built with specifications often favored by racing applications, translating to increased power stability in utility engines.
• Fits Wide Range of HP: Suitable for small 5.5HP motors up to massive 16HP engines.

Pros:
– Handles heavy-duty, long-duration generator use exceptionally well.
– Provides crisp ignition and strong idling stability.
– Excellent direct fit for common Honda GX engines.

Cons:
– Buyers must confirm the colder F7TC heat range is suitable for their specific environment.

Best for: Users running generators in high-demand, continuous operational scenarios.

Expert Opinion: If you use your generator as a primary power source for tools or an off-grid cabin, the enhanced heat handling capabilities of this plug provide a noticeable boost in reliability and longevity compared to basic OEM models.

PK2 TORCH F7TC Spark Plug Replace for NGK 3785 BP7ES Spark Plug, Compatible with GX120 160 200 240 270 340 390 Generator Lawnmower Tractor Go Kart Mini Bike Polishing Machine 168F 168FA 168FB, OEM

TORCH is a well-established manufacturer, and this PK2 F7TC spark plug leverages that history to deliver reliable performance. This particular model focuses on improving fuel efficiency and reducing emissions—a great benefit for those concerned about their generator’s environmental impact during long runs. Its robust compatibility with both name-brand Honda engines and the vast array of Chinese clones (like 168F and 190F) makes it a very versatile replacement piece.

Key features that stand out:

• Manufacturer Pedigree: Backed by decades of manufacturing history and R&D from the TORCH brand.
• Performance Benefits: Specifically designed for fast starts, improved fuel efficiency, and reduced emissions.
• Broad Clone Engine Fitment: Excellent choice for less common imported generator engines.

Pros:
– Strong reputation for stable performance and long service life.
– Direct cross-reference to major plugs like NGK BP7ES and Champion N9YC.
– Helps maximize the burn cycle for better gas mileage.

Cons:
– Availability can sometimes fluctuate compared to domestic brands.

Best for: Generator owners looking for a trusted, high-performance OEM alternative with a focus on engine longevity and efficiency.

Expert Opinion: The focus on hydrocarbon emissions reduction makes this a slightly “greener” choice without sacrificing the quick, reliable starts every generator user needs. This is a top contender for the best spark plugs for generators in the efficiency category.

GREPSPUD 2pcs F7TC Spark Plugs GX120 GX160 GX200 GX240 GX270 GX340 GX390 Sparkplugs for Generator Lawnmower Chainsaw Tractor Rototiller Water Pump Go Kart Mini Bike, with Spark Plug Boot Caps & Wrench

The GREPSPUD 2-piece kit isn’t just about the spark plugs; it’s about the complete maintenance experience. This package is ideal for the new generator owner or someone performing an overdue tune-up, as it includes two high-quality F7TC plugs, two spark plug boot caps, and a dedicated spark plug wrench. This provides everything needed in one convenient purchase, saving time tracking down separate tools and parts.

Key features that stand out:

• Complete Maintenance Kit: Includes 2 F7TC plugs, 2 boot caps, and a wrench—a tremendous value addition.
• Excellent Corrosion Resistance: Features a design intended to maximize service life, even in damp or humid storage conditions.
• Strong, Powerful Ignition: Engineered to deliver a strong spark burst, ensuring reliable starting even after long periods of inactivity.

Pros:
– Eliminates the need to buy a separate wrench.
– The included caps are useful if existing boots are cracked or worn.
– Focuses on a wide heat range for versatility across engine types.

Cons:
– The included wrench, while functional, might not be as heavy-duty as professional tools.

Best for: First-time generator maintenance, or anyone needing a convenient, all-in-one replacement kit.

Expert Opinion: We appreciated that GREPSPUD provided the ancillary parts. For small engine maintenance, often the simplest things (like having the right wrench) make the biggest difference in getting the job done quickly.

TORCH F6TC Spark Plug 131-047 Replace for NGK BP6ES, for Bosch W6D, for CHAMPION N9YC Spark Plug, for Honda GX140 GX160 GX200 5.5hp 6.5hp Engine Generator, OEM, ea

Returning to the trusted TORCH brand, this F6TC plug is a slightly different heat range offering than the F7TC models reviewed above. The F6TC is often the OEM standard for smaller 5.5hp and 6.5hp Honda GX engines (like the GX140, GX160, and GX200). Choosing the correct heat range is crucial for optimal performance, and this plug ensures you are installing the exact thermal match recommended by many major engine manufacturers. It promises the same reliable performance, fast starting, and long lifespan associated with the TORCH name.

Key features that stand out:

• Specific Heat Range Match: F6TC is often the required OEM plug for many mid-sized engines.
• Certified Compatibility: Guaranteed replacement for NGK BP6ES and Champion N9YC.
• Stable Performance: Built to reduce emissions and improve overall fuel efficiency in compatible engines.

Pros:
– Ideal for maintaining exact OEM specifications on smaller Honda GX generators.
– Built to handle consistent, long-term operation.
– Ensures fast and consistent cold starts.

Cons:
– Sold individually (ea), which means less value than a multi-pack.

Best for: Generator owners focused strictly on replacing their plug with the precise, OEM-specified F6TC heat range.

Expert Opinion: Using the correct heat range is critical to avoid fouling (if the plug is too cold) or overheating/pre-ignition (if the plug is too hot). For those specific GX models, the F6TC is often the safest and most reliable choice.

GREPSPUD 4pcs F7TC Spark Plugs GX120 GX160 GX200 GX240 GX270 GX340 GX390 Sparkplugs with Wrench for 4-Stroke Engine Generator Lawnmower Chainsaw Tractor Water Pump Rototiller Go Kart Mini Bike

If you loved the idea of the GREPSPUD kit but maintain a fleet of generators or small equipment, this 4-piece F7TC set is an excellent investment. Similar to their 2-pack, it includes a high-quality steel spark plug wrench for convenience. The increased quantity ensures you have backup spark plugs ready for multiple maintenance cycles or for replacing the plugs in several machines simultaneously. Like other F7TC models, these are designed for wide compatibility and superior corrosion resistance.

Key features that stand out:

• Bulk Value: Comes with four reliable F7TC spark plugs, ideal for stocking up.
• Durable Wrench Included: Provides a durable, quality steel wrench (180mm length) for ease of installation.
• Excellent Ignition Burst: Designed to promote more complete fuel burning and reduce carbon buildup.

Pros:
– Best value proposition for bulk buying with an included tool.
– Superior anti-corrosion properties are great for equipment stored outdoors.
– Consistent and strong performance across various engine sizes.

Cons:
– Might be too many plugs if you only own one generator.

Best for: Landscapers, fleet managers, or home users who need to stock up on reliable replacement plugs for multiple pieces of equipment.

Expert Opinion: When looking for the best spark plugs for generators, value often means minimizing downtime. Having four of these reliable plugs and the correct wrench on hand ensures that maintenance is quick and inexpensive whenever needed.

F7TC Spark Plug Fit for Harbor Freight Predator 6.5HP 212cc 13HP 420cc Gas Engine Fit for Champion CPE Fit for Honda Fit for WEN Fit for Duromax Fit for Pulsar Non-Inverter 3.5-9KW Gas Generator 2Pcs

This 2-piece F7TC offering excels in its specific focus on popular non-inverter gas generators, particularly those utilizing Harbor Freight’s extremely common Predator engines (212cc and 420cc). While many plugs are generally compatible, this product explicitly guarantees fitment for generators in the crucial 3.5KW to 9KW range from major consumer brands like Champion, Duromax, and Pulsar. The quality materials ensure reliable starting power, which is paramount for emergency backup units.

Key features that stand out:

• Predator Engine Specific: Explicitly guarantees fitment for the highly popular Predator 212cc and 420cc engines.
• Non-Inverter Generator Focus: Ideal replacement for standard, workhorse generators up to 9,000 watts.
• Strict Quality Control: Claims stringent testing to ensure peak performance right out of the box.

Pros:
– Strong compatibility assurance for specific consumer-grade generator models.
– Reliable replacement for high-demand 13HP engines.
– Comes in a practical and economical 2-pack.

Cons:
– Less necessary for owners of small inverter or specialized engines.

Best for: Owners of Harbor Freight Predator engines or standard heavy-duty emergency generators (3.5KW to 9KW).

Expert Opinion: When dealing with high-output generators, quality control is essential. Knowing this plug is specifically tested for the performance envelope of 3.5-9KW non-inverter models provides excellent confidence during critical startup moments.

Comparison Insights: Choosing The Right Generator Spark Plug

Choosing the right plug for your generator often comes down to two key factors: engine type (especially the ubiquitous Honda GX clones) and the heat range required.

The Heat Range Factor (F6TC vs. F7TC):
You might notice the designations F6TC and F7TC. The F6TC is considered a “hotter” plug and is generally the factory recommendation for smaller Honda GX engines (like the GX140/160/200). The F7TC is a slightly “colder” plug, meaning it transfers heat away from the tip faster. Colder plugs (like the F7TC) are better if you run your engine under consistently heavy load or in high ambient heat, as they help prevent overheating and pre-ignition. If your generator is highly stressed, choosing an F7TC (like in the FLYPIG or GREPSPUD kits) is often safer, but always check your owner’s manual first.

Best for Universal Compatibility & Value:
The YAMAKATO 3-Pack wins here due to its sheer number of cross-references and the added bonus of thread tape. It covers the widest array of engine sizes and plug types (BPR6ES, RN9YC).

Best for Convenience and Complete Kits:
If you need tools included, the GREPSPUD 2pcs F7TC Kit or the GREPSPUD 4pcs F7TC Kit are the top choices. Having the correct wrench and extra boot caps (in the 2-pack) ensures the replacement job is hassle-free.

Best for Specific Engine Fitment:
Owners of the popular Predator 212cc/420cc engines will find the F7TC Spark Plug Fit for Harbor Freight Predator model the most reassuring, as it targets those specific powerplants directly.

Final Verdict: Our Pick for the Best Spark Plugs For Generators

Selecting the absolute best spark plugs for generators depends on your maintenance style and equipment usage.

The Reliable All-Rounder

For most homeowners and small business users running common Honda GX-style engines (GX200, GX390) or their clones, we recommend the PK2 TORCH F7TC Spark Plug. It blends decades of reliable manufacturing history with enhanced performance features, ensuring the best mix of quick starts and improved fuel efficiency over the long haul.

Best Bulk Value

If you service multiple machines or want to minimize replacement costs over several years, the GREPSPUD 4pcs F7TC Spark Plugs with Wrench offers the highest quantity of high-performance plugs, plus the essential installation tool, delivering undeniable long-term value.

Best for OEM Fidelity

If your generator manual calls specifically for the NGK BPR6ES replacement, the TORCH F6TC Spark Plug is the ideal choice, providing the exact factory-specified heat range for smaller generator engines.

Best Spark Plugs For Generators FAQ

What are the signs that my generator spark plug needs to be replaced?

The most common sign is difficult starting, especially when the engine is cold. Other indicators include rough idling, decreased fuel efficiency, frequent fouling (where the plug becomes covered in black, oily residue), or the engine completely failing to start. As a rule of thumb, most manufacturers recommend checking or replacing the spark plug every 100 hours of run time or annually, whichever comes first.

What is the difference between an F6TC and F7TC spark plug?

This designation refers to the plug’s heat range. The number indicates how quickly the plug transfers heat away from the tip. The F7TC is a slightly “colder” plug than the F6TC. Colder plugs are typically used in high-output engines or high-stress applications (like continuous heavy generator use) because they are less prone to overheating, pre-ignition, and electrode melting.

How do I properly gap my new spark plug?

While many replacement spark plugs come pre-gapped, it is crucial to verify the gap size using a wire feeler gauge before installation. The correct gap size is specific to your generator’s engine. For most common small generators (like the Honda GX series or Predator), the gap is often between 0.028 and 0.032 inches (0.7 to 0.8 mm). Always consult your generator’s owner’s manual for the exact specification to ensure the best spark plugs for generators operate correctly.

Can I use an automotive spark plug in my portable generator?

No, generally you should not. While some plug types may physically fit, automotive plugs are designed for different operating environments, heat ranges, and vibration levels. Generator spark plugs are typically designed to handle the prolonged, continuous operation and specific thermal requirements of air-cooled small engines. Using the wrong plug can lead to severe engine damage or poor performance.

Should I choose a copper, platinum, or iridium spark plug for my generator?

Most small generators are designed to run perfectly well on standard copper-core spark plugs (like the F7TC or F6TC plugs reviewed here). Copper plugs offer excellent conductivity and are very affordable. While iridium and platinum plugs offer longer lifespans in cars, the high vibration and specific heat cycling of portable generators often make their longevity benefits less pronounced, and they rarely offer a performance boost in these types of engines.

What maintenance should I perform after installing a new spark plug?

After replacing the spark plug, it’s a great time to perform other essential generator maintenance. Check your air filter for debris and consider changing the engine oil. Ensure the spark plug boot is firmly seated to prevent arcing, and check the fuel quality. This comprehensive check ensures your generator will provide reliable emergency backup power.