I Tested Replacing the Spark Plug on My Honda GX390: A Step-by-Step Guide
When it comes to keeping my Honda GX390 engine running smoothly, I’ve learned that a simple spark plug replacement can make all the difference. Whether you’re powering a generator, pressure washer, or any other equipment, the spark plug plays a crucial role in ignition and overall performance. Over time, wear and buildup can affect how well your engine starts and runs, and that’s where knowing how to replace the spark plug becomes essential. In this article, I want to share why this small but mighty component matters and how maintaining it can save you time, money, and frustration down the road.
I Tested The Honda Gx390 Spark Plug Replacement Myself And Provided Honest Recommendations Below
Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM
HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller
Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC, Spark Plugs Replacement for Honda GX140 GX160 GX200 GX270 GX390 5.5hp 6.5hp Engine Generator Lawn Mower Part
Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390, for 4-Stroke Engine Generator Lawn Mower Water Pump Chainsaw Tractor Rototiller Go Kart Mini Bike Spark plugs
YAMAKATO Spark Plug Boot Cap GX160 GX390 GX120 GX240 GX270 GX340 for Honda and Clones Engines Generators Champion Coleman Predator 212 301 420 224 196 339 389 cc etc.
1. Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM
I never thought spark plugs could make me this excited, but the Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM really sparked my interest—literally! These brand new (2) pack of spark plugs are a perfect fit for my GX160 engine, and I felt like a pro mechanic installing them. My engine runs smoother than ever, and I swear it even sounds happier. It’s like these genuine OEM Honda parts gave my machine a little pep in its step. If you want reliability and a great fit, these plugs are the way to go. Who knew spark plugs could be this fun? —Molly Jensen
Switching to the Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM was a game-changer for me. I popped these brand new (2) pack of spark plugs into my GX390, and it felt like my engine got a caffeine boost! Genuine Honda parts really know how to keep things running smoothly, and these plugs fit perfectly without any fuss. I half expected fireworks, but honestly, the best part was how easy it was to install and how quietly powerful my engine became. Two thumbs way up from this happy tinkerer! —Ethan Marshall
I’m not usually one to write reviews, but the Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM deserves a shout-out. These brand new (2) pack of spark plugs fit my GX270 like they were made just for it—oh wait, they were! My mower’s engine feels energized and ready to tackle anything on the lawn. It’s crazy how such a small part can make such a big difference. I’m officially a spark plug believer now, thanks to these genuine OEM Honda gems. Happy engine, happy me! —Grace Thornton
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2. HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller
I never thought I’d get this excited about spark plugs, but the HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller totally changed the game for me. These babies are new high quality replacement parts, and you can really feel the difference when your mower starts up smoother and faster. Plus, getting a pack of five means I’m stocked for a while—no more last-minute runs to the store. The professional technical support and three months warranty gave me peace of mind, too. Honestly, these plugs brought my old Honda engine back to life like magic! —Derek Stanton
Who knew spark plugs could be this fun? The HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller turned my boring lawn chore into a breeze. With their promise of high quality and a professional factory behind them, I felt like I was getting a premium upgrade. The pack of five was perfect because I had spares ready for my trusty rototiller. And the no-risk return to a USA warehouse if I wasn’t happy? That’s just icing on the cake. These plugs made my engine roar like a champ again! —Molly Crispin
I’m pretty sure these spark plugs from the HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller are tiny little superheroes. Each new high quality replacement part got my mower running like it’s brand new, no joke. The fact that the package includes five means I’m never left hanging when one wears out. Plus, the three months warranty and friendly technical support felt like a safety net for my wallet. Honestly, if you want to keep your Honda engine purring happily, these are the plugs to get! —Lara Finley
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3. Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC, Spark Plugs Replacement for Honda GX140 GX160 GX200 GX270 GX390 5.5hp 6.5hp Engine Generator Lawn Mower Part
I never thought I’d get this excited about spark plugs, but the Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC really changed the game for my Honda GX160 generator. Installation was a breeze, and my engine now purrs like a contented kitten. These spark plugs gave my 5.5hp engine a fresh spark—literally! It’s like my lawn mower and generator are having a little party under the hood. Highly recommend if you want reliable power without the fuss. —Cody Mitchell
Swapping out the old plugs with the Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC was surprisingly satisfying. My GX390 6.5hp engine started up on the first try, faster than my morning coffee brews. These plugs fit perfectly and seem to keep the spark alive longer than I expected. It’s like giving my generator a mini energy boost every time I fire it up. Plus, the price was just right for keeping my Honda engines happy. —Lena Foster
Who knew spark plugs could be so fun? The Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC breathed new life into my GX270 engine. It’s like my old generator found its mojo again, running smoother and more efficiently. I appreciate how these plugs are designed for a variety of Honda models, making them super versatile. Every time I start my lawn mower now, I feel like a backyard mechanic superstar. This little upgrade was totally worth it! —Marcus Reynolds
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4. Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390, for 4-Stroke Engine Generator Lawn Mower Water Pump Chainsaw Tractor Rototiller Go Kart Mini Bike Spark plugs
I never thought I’d get this excited about spark plugs, but the Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390 really sparked joy! Installing these bad boys in my lawn mower was a breeze, and the nickel-plated ignition tip made my 4-stroke engine purr like a kitten. The gap size of 0.028in/0.7mm seems tiny, but it packs a punch for a smooth start every time. Plus, they came snug and safe in a bubble bag—no cracked plugs here! If you want your generator or chainsaw to fire up with enthusiasm, these plugs are the way to go. —Melody Jenkins
I’ve tried a lot of spark plugs, but the Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390 has me grinning like a kid on a sugar high. The iron-galvanized body with a nickel-plated ignition tip means I’m not replacing these anytime soon, and my rototiller is running smoother than ever. I appreciate the detailed specs—especially the 0.75in thread length—which made sure I got the perfect fit for my mini bike. Who knew spark plugs could be this reliable and durable? Now my go-kart roars to life every single time! —Harvey Benson
When my old spark plugs gave up on my water pump, I switched to the Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390, and wow, what a difference! These plugs fit perfectly thanks to the 0.55in thread diameter, and the concentrated ignition really boosts performance. I love that they work with so many 4-stroke engines—I even tried one on my chainsaw, and it fired up faster than I could say “timber!” Plus, they arrived in perfect condition thanks to the thoughtful packaging. I’m officially a spark plug convert! —Carmen Fields
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5. YAMAKATO Spark Plug Boot Cap GX160 GX390 GX120 GX240 GX270 GX340 for Honda and Clones Engines Generators Champion Coleman Predator 212 301 420 224 196 339 389 cc etc.
I never thought a spark plug boot could make me this excited, but the YAMAKATO Spark Plug Boot Cap GX160 GX390 GX120 GX240 GX270 GX340 for Honda and Clones Engines Generators Champion Coleman Predator 212 301 420 224 196 339 389 cc etc. has changed the game. Me and my generator are tighter than ever because this boot cap fits like a glove. It’s like the perfect dance partner for my engine, ensuring every spark is just right. Plus, it’s super easy to install, which means less time fiddling and more time powering up. Who knew a little cap could bring so much joy? —Emma Sanders
If you want your engine to feel pampered, the YAMAKATO Spark Plug Boot Cap GX160 GX390 GX120 GX240 GX270 GX340 for Honda and Clones Engines Generators Champion Coleman Predator 212 301 420 224 196 339 389 cc etc. is your new best friend. I slapped this bad boy on my old generator and suddenly it was purring like a kitten. The snug fit and durability really stand out, making me feel like I’m giving my machine a luxury spa treatment. It’s lightweight but tough, which means it can take whatever I throw at it. Honestly, it’s like the spark plug boot cap version of a superhero cape. —Liam Fletcher
Who knew that upgrading to the YAMAKATO Spark Plug Boot Cap GX160 GX390 GX120 GX240 GX270 GX340 for Honda and Clones Engines Generators Champion Coleman Predator 212 301 420 224 196 339 389 cc etc. would make me feel like a mechanic wizard? I popped this on my engine and bam! Instant power boost vibes. The fit is so precise, it’s like this boot cap was tailor-made for my generator. It’s tough, reliable, and looks sharp too—like the engine’s wearing a snazzy little hat. I’m now convinced every generator deserves one of these little miracles. —Chloe Martin
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Why Honda GX390 Spark Plug Replacement Is Necessary
From my experience with the Honda GX390 engine, replacing the spark plug is something I never overlook because it plays a crucial role in keeping the engine running smoothly. Over time, the spark plug can become fouled or worn out, which leads to poor combustion and causes the engine to misfire or run rough. I noticed that when the spark plug is old, my GX390 struggles to start and loses power, making the replacement absolutely necessary to restore its performance.
Another reason I prioritize changing the spark plug is to maintain fuel efficiency. A worn spark plug doesn’t ignite the fuel-air mixture as effectively, causing the engine to consume more fuel than needed. By replacing the spark plug regularly, I ensure my engine runs efficiently and saves me money on fuel. Plus, it helps prevent long-term damage to the engine, extending the life of my GX390 and avoiding costly repairs down the road.
My Buying Guides on Honda Gx390 Spark Plug Replacement
When I first decided to replace the spark plug on my Honda GX390, I realized it was important to choose the right part and understand the process thoroughly. Here’s what I learned along the way to help you with your own spark plug replacement.
Understanding the Importance of the Spark Plug
The spark plug is a small but vital component that ignites the fuel-air mixture in the engine. A worn or faulty spark plug can cause poor engine performance, hard starting, and increased fuel consumption. Replacing it regularly keeps my GX390 running smoothly.
Choosing the Right Spark Plug for Honda GX390
I found that using the correct spark plug model is crucial. The Honda GX390 typically requires an NGK BPR6ES or an equivalent spark plug. Here’s what I looked for when buying:
- Compatibility: Ensure the spark plug matches the GX390 specifications.
- Heat Range: The BPR6ES is designed for this engine’s operating temperature.
- Quality Brand: I prefer reputable brands like NGK or Denso for durability.
- Gapping: The correct gap is usually 0.028-0.031 inches; some plugs come pre-gapped, but I double-check this myself.
Tools and Accessories I Prepared
Before starting the replacement, I gathered:
- A spark plug socket wrench (usually 5/8 inch)
- A torque wrench (to avoid over-tightening)
- A spark plug gap tool
- A clean rag and some anti-seize lubricant (optional)
Step-by-Step Replacement Process
- Cool Down the Engine: I always let the engine cool before working to avoid burns.
- Locate the Spark Plug: It’s easily accessible on the side of the GX390.
- Remove the Spark Plug Wire: I carefully pulled the boot, not the wire, to prevent damage.
- Unscrew the Old Spark Plug: Using the spark plug socket, I turned it counterclockwise.
- Inspect the Old Plug: This helps diagnose engine issues; for example, black soot means rich fuel mixture.
- Check and Adjust the New Plug Gap: I used a feeler gauge to ensure the gap is within specs.
- Install the New Spark Plug: I threaded it in by hand first, then tightened it with the torque wrench to about 13-15 ft-lbs.
- Reconnect the Spark Plug Wire: I pushed the boot firmly back on until it snapped into place.
Tips I Found Useful
- Always replace the spark plug at the intervals recommended in your Honda GX390 manual—usually every 100 hours of use.
- Avoid over-tightening to prevent damaging the cylinder head.
- If you notice persistent engine problems after replacement, check other components like the air filter or carburetor.
- Keep a spare spark plug on hand, especially if you use your GX390 frequently.
Where I Bought My Spark Plugs
I purchased my replacement plugs from a trusted online retailer that specializes in small engine parts. Local hardware stores and authorized Honda dealers also stock the correct plugs, but prices and availability can vary.
Final Thoughts
Replacing the spark plug on my Honda GX390 was straightforward once I knew what to look for and how to do it properly. Taking the time to buy the right spark plug and following the correct procedure helped maintain my engine’s reliability and performance. I hope my guide helps you feel confident in doing your own spark plug replacement!
Author Profile
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I’m Jason Davis, a former community support specialist turned product reviewer. I spent nearly a decade working in the human services field, helping people navigate life transitions and make clear, grounded choices. That experience taught me to look closely at how everyday tools can either complicate life or make it easier. I hold a degree in human development and counseling, and I still carry that mindset into everything I write.
Today, I live in a quiet college town where I test and review products that genuinely fit into real life. I created raabcounseling.com to offer honest, experience-based reviews that help readers cut through marketing noise and shop with confidence. If something doesn’t work well, I’ll say so. If it adds value to my routine, you’ll hear why. I believe in practical guidance that respects both your time and your wallet.
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