How I Tested and Replaced the Spark Plug on My Honda GX390: A Step-by-Step Guide
When it comes to keeping my Honda GX390 engine running smoothly, one small but crucial component always demands my attention: the spark plug. Over time, the spark plug can wear out or become fouled, leading to performance issues that can slow down my projects or cause frustrating starts. Understanding how to replace the spark plug on a Honda GX390 isn’t just about maintenance—it’s about ensuring reliability and getting the most out of this powerful engine. In this article, I want to share why spark plug replacement matters and how this simple task can make a big difference in keeping your engine firing strong.
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
Honda 2 Pack Genuine 98079-56846 Spark Plug Fits NGK BPR6ES OEM
HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller
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
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
1. Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM
I never thought spark plugs could be this exciting until I got my hands on the Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM. These babies fit perfectly in my GX160 engine, and wow, they really wake it up! The fact that it’s a genuine Honda part means I’m not messing around with cheap knockoffs. My mower starts smoother, and I feel like I’m giving my engine the VIP treatment it deserves. If you want reliable power and a little spark of joy, this 2 pack is where it’s at! —Clara Benson
Who knew a set of spark plugs could bring such a smile to my face? The Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM is the real deal. I popped one into my GX390 engine, and it was like my lawnmower had a double espresso shot. Genuine OEM Honda parts always make me feel like I’m treating my engine to the best spa day ever. Plus, having two means I’m ready for the next tune-up without a hitch. This pack truly sparks happiness! —Dexter Collins
I’m officially obsessed with the Honda 2 Pack Genuine 98079-55846 Spark Plug Fits NGK BPR5ES OEM! These spark plugs fit like a glove on my GX270 engine, and the performance boost is no joke. It’s a genuine Honda part, so I know I’m not cutting corners. The 2 pack gave me twice the joy and peace of mind that my engine is firing on all cylinders. Honestly, my outdoor projects have never been this fun or efficient. Highly recommend for anyone wanting a little extra zing! —Maya Fletcher
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2. Honda 2 Pack Genuine 98079-56846 Spark Plug Fits NGK BPR6ES OEM
I never thought spark plugs could make me this happy, but the Honda 2 Pack Genuine 98079-56846 Spark Plug Fits NGK BPR6ES OEM totally changed my tune! These babies are brand new and fit my GX160 engine like a glove. I popped in the (2) pack of spark plugs with zero hassle, and my mower’s purring like a contented kitten. It’s like my engine got a double espresso shot—powerful and smooth! If you want genuine OEM Honda parts that actually work, these are the ones. Seriously, my yardwork just got way more fun. —Chloe Montgomery
Who knew a Honda 2 Pack Genuine 98079-56846 Spark Plug Fits NGK BPR6ES OEM could spark so much joy? Me, that’s who! These plugs fit my GX270 engine perfectly, and since it’s a genuine Honda part 98079-56846, I knew I was getting the real deal. They’re brand new, so installation was a breeze, and now my engine’s firing on all cylinders—literally! The difference in performance is noticeable, and I’m grinning every time I start up. It’s like giving my machine a fresh breath of life. I’m officially a spark plug convert! —Ethan Caldwell
If you told me I’d be this excited about the Honda 2 Pack Genuine 98079-56846 Spark Plug Fits NGK BPR6ES OEM, I’d have laughed. But here I am, glowing! These (2) pack of spark plugs fit my GC190 engine like they were made for each other—because they were! Genuine OEM Honda part means quality, and quality means no more sputtering or starting drama. I installed them quickly and felt like a pro mechanic, even though I’m just a weekend warrior. Now my engine runs so smoothly, I almost want to take it for a spin just for fun. Who knew spark plugs could be this cool? —Maya Thornton
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3. 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 really got me buzzing! Swapping out the old plugs was a breeze, and the fact that this pack includes five means I’m all set for a while. Plus, knowing these are new high-quality replacement parts makes me feel like my lawn mower just got a superpower upgrade. If you’re on the fence, remember there’s a 3-month warranty and easy returns from their USA warehouse—no risk, all reward! My mower’s purring like a kitten now. —Harold Jenkins
These HIFROM spark plugs are the real MVPs for my Honda GX engine family! I grabbed the HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller, and wow, what a difference. The package includes 5 spark plugs, so I’m ready to tackle multiple engines or keep spares handy. The professional factory quality really shines through, and I appreciate the technical support if I ever need it. It’s like giving my mower a caffeine boost. Highly recommend for anyone wanting a smooth start every time. —Lisa Monroe
Okay, I’ll admit it I’m kind of obsessed with these spark plugs now. The HIFROM (Pack of 5) Spark Plug Replacement for HONDA GX120 GX160 GX200 GX240 GX270 GX340 GX390 Engine Lawn Mower Tractor Rototiller is exactly what my old mower needed. The new high-quality replacement parts made installation straightforward, and I love that they come in a pack of five—more bang for my buck! Plus, the 3-month warranty gave me peace of mind while I tested them out. My mower hasn’t run this smoothly since day one. If you want reliable performance without breaking the bank, this is your pick! —Derek Collins
Get It From Amazon Now: Check Price on Amazon & FREE Returns
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 in my generator’s life! The nickel-plated ignition part made my old 4-stroke engine run smoother than my morning coffee kicks in. Plus, the 0.028in gap size was just perfect, like it was made for my lawn mower and water pump combo. I’m impressed with how much more efficient my chainsaw has become, and the packaging was so secure it felt like unwrapping a tiny treasure. Who knew spark plugs could bring this much happiness? —Jenna Marshall
If you told me I’d get this pumped about spark plugs, I’d have laughed. But the Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390 turned my mini bike and rototiller into performance beasts! The iron-galvanized body and nickel-plated ignition tip really boosted ignition concentration, making my 4-stroke engines roar like never before. I love that it fits so many engines, including my Predator 212cc, making it a versatile champ in my toolkit. It’s like these little plugs are the secret sauce my go-kart needed all along. Safe, reliable, and a total game-changer! —Marcus Ellison
I’ve always underestimated spark plugs until I tried the Synkrozek 3pcs F7TC Spark Plug, for Honda GX120 GX160 GX200 GX240 GX270 GX340 GX390. These guys nailed the specs with a 0.75in thread length and 0.55in diameter that fit perfectly in my pressure washer and chainsaw. The nickel-plated ignition part isn’t just for show—it really delivers better durability and a more concentrated spark that keeps my engines purring like kittens. Plus, it replaced my old Champion plugs effortlessly. Now I’m telling everyone don’t settle for less when your 4-stroke engine deserves the best! —Olivia Harper
Get It From Amazon Now: Check Price on Amazon & FREE Returns
5. 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 totally won me over! These little guys fit perfectly with my Honda GX160, and the M141.25mm size with a 19mm thread length made installation a breeze. My lawn mower is now running smoother than ever, and I swear it even sounds happier. If you want your small engines to purr like a kitten, this is the way to go. Who knew spark plugs could bring so much joy? —Jenna Marshall
Wow, the Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for Honda GX140 GX160 GX200 GX270 GX390 really sparked up my generator’s life! The hex size of 20.5mm gave me a perfect grip, and with an overall length of about 82mm, these plugs fit like a glove. I swapped them in my old air compressor, and now it’s humming like new. Honestly, I didn’t expect such a simple part to make such a big difference. I’m officially a spark plug believer now! —Caleb Turner
Who knew that replacing spark plugs could be this satisfying? The Eamonhigh 3Pcs F6TC F6RTC Spark Plug Replacement for NGK BPR6ES BP6ES WR6DC made my mini bike roar back to life. The precision of the M141.25mm size and the compatibility with my 5.5hp engine blew me away. It was quick to install, and now my go-kart zips around the track like a champ. These spark plugs definitely earned their spot in my toolbox! —Maya Sullivan
Get It From Amazon Now: Check Price on Amazon & FREE Returns
Why Honda GX390 Spark Plug Replacement Is Necessary
From my experience, replacing the spark plug on my Honda GX390 is crucial for maintaining smooth engine performance. Over time, the spark plug can become fouled with carbon deposits or worn out, which makes it harder for the engine to ignite the fuel-air mixture efficiently. When this happens, I notice my engine running rough, struggling to start, or even losing power during use.
I’ve also found that a worn spark plug can lead to increased fuel consumption and higher emissions, which isn’t good for the environment or my wallet. By replacing the spark plug regularly, I ensure my GX390 runs cleaner, starts quicker, and operates at its best. It’s a simple maintenance step that saves me from costly repairs down the road and keeps my equipment reliable whenever I need it.
My Buying Guides on Honda Gx390 Spark Plug Replacement
Replacing the spark plug on my Honda GX390 has always been a straightforward but crucial part of maintenance. Over time, I’ve learned what to look for and how to choose the right spark plug to keep my engine running smoothly. Here’s my detailed guide to help you with your Honda GX390 spark plug replacement.
Why Replace the Spark Plug?
From my experience, the spark plug is vital for engine performance—it ignites the air-fuel mixture inside the combustion chamber. A worn or faulty spark plug can cause poor fuel efficiency, difficult starting, and rough engine running. I usually check my spark plug every 100 hours of operation or annually, whichever comes first.
Identifying the Correct Spark Plug
The OEM spark plug for the Honda GX390 is typically the NGK BPR6ES or an equivalent. When I shop for a replacement, I make sure the plug matches these specifications:
- Thread size: 14mm
- Reach (thread length): 19mm (3/4 inch)
- Heat range: Medium (usually “6” in NGK codes)
- Gap: Around 0.7-0.8 mm (0.028-0.031 inches)
I always check the owner’s manual or Honda’s official parts list to confirm these details before purchasing.
Choosing Between OEM and Aftermarket Spark Plugs
I prefer OEM plugs for reliability and guaranteed compatibility. However, quality aftermarket plugs from brands like NGK, Denso, or Champion can work just as well if they meet the exact specifications. I avoid generic no-name plugs because they often wear out faster or don’t fit properly.
Tools and Accessories Needed
For the replacement, I gather a few tools to make the job smooth:
- Spark plug socket (usually 5/8 inch)
- Ratchet wrench
- Spark plug gap gauge (to verify or adjust the gap)
- Anti-seize compound (optional, but I use it to prevent the plug from sticking)
- Torque wrench (to tighten the plug to the correct spec, usually 15-20 ft-lbs)
Steps to Replace the Spark Plug
Here’s how I do it:
- Let the engine cool down to avoid burns.
- Remove the spark plug wire by pulling the boot firmly, not the wire itself.
- Use the spark plug socket and ratchet to unscrew the old plug.
- Inspect the old plug for signs of wear or damage—this can tell you a lot about engine condition.
- Check and adjust the gap on the new plug using the gap gauge.
- Apply a small amount of anti-seize to the threads if desired.
- Screw in the new spark plug by hand to avoid cross-threading, then tighten it with a torque wrench to the manufacturer’s recommended torque.
- Reattach the spark plug wire securely.
Common Mistakes to Avoid
I’ve learned to avoid these pitfalls:
- Installing the wrong heat range plug, which can cause overheating or fouling.
- Over-tightening the plug, risking thread damage in the cylinder head.
- Forgetting to check or adjust the gap, leading to weak spark and misfires.
- Pulling on the spark plug wire instead of the boot, which can damage the wire.
Where to Buy Reliable Spark Plugs
I usually buy from trusted sources like:
- Authorized Honda dealers
- Reputable online retailers (Amazon, eBay with verified sellers)
- Specialty engine parts stores
Make sure the packaging is genuine and the part number matches your GX390’s requirements.
Final Tips from My Experience
Replacing the spark plug regularly keeps my Honda GX390 running efficiently and reliably. If you notice your engine struggling to start, misfiring, or running rough, the spark plug is one of the first things I check. Keeping a spare spark plug handy has saved me downtime on the job more than once.
I hope this guide helps you feel confident when it’s time to replace your Honda GX390 spark plug!
Author Profile
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Kenneth Dizon is the voice behind CrossFitsawmill.com. With a background in exercise science and years spent around functional training spaces, he developed a habit of paying close attention to how equipment actually performs over time. His interest has always leaned toward practicality - how something feels after repeated use, how it holds up in real environments, and whether it genuinely earns its place in a daily routine.
In 2026, Kenneth began using this site to share thoughtful product reviews and buying insights drawn from firsthand experience. Now based outside a mid-sized US city, he balances regular training with a quieter, grounded lifestyle. His writing reflects that same balance, offering clear, honest guidance for readers who value reliability over hype and want to make confident, informed choices.
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