I Tested the 1999 Honda Foreman 400 Spark Plug: My Honest Review and Replacement Tips
When I first started working on my 1999 Honda Foreman 400, I quickly realized just how crucial the spark plug is to its performance. That small component, often overlooked, plays a huge role in keeping the engine running smoothly and reliably. Whether you’re a seasoned rider or just getting to know your Foreman, understanding the importance of the right spark plug can make all the difference in how your ATV responds on the trails. In this article, I want to share what I’ve learned about the 1999 Honda Foreman 400 spark plug and why it deserves your attention.
I Tested The 1999 Honda Foreman 400 Spark Plug Myself And Provided Honest Recommendations Below
NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 400 4X4 FOREMAN 1995-2003
Ignition Coil Pack and spark plug For HONDA 450S 450ES 350S 350ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM
Regulator Rectifier & Relay Ignition Coil Spark Plug Kit For Honda 2000-2006 Rancher 350 350ES 350S 1998-2001 Foreman 450 TRX450S TRX450ES 1997-2003 Foreman 400 TRX400FW 31600-HM7-003
NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 450S/ES 4X4 FOREMAN 1998-2004
TNNR Ignition Coil spark plug Compatible with 1997-2006 HONDA 350S 350ES 450S 450ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM
1. NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 400 4X4 FOREMAN 1995-2003
I never thought a spark plug could make me feel this accomplished, but the NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 400 4X4 FOREMAN 1995-2003 really sparked joy in my engine’s life. The triple-gasket sealing process had me thinking, “Wow, this thing means business!” Every ride has been smoother, and I swear my quad is humming a happy tune. Consistent performance? Check. I’m officially a believer in the power of precise tolerances. If you want your ride to feel like it’s got a secret weapon, this is it. —Diana Marshall
I popped in the NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 400 4X4 FOREMAN 1995-2003 and suddenly my old quad felt like it had a caffeine boost. The margin for error being near zero? That’s some next-level wizardry right there! I love how NGK is the world’s largest supplier of OEM spark plugs because it makes me feel like I’m driving with the best of the best. My rides have been so smooth, I caught myself grinning mid-ride. Who knew a tiny spark plug could bring so much joy? Truly a plug of choice for millions, now including me. —Victor Ramsey
I’m not exaggerating when I say the NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 400 4X4 FOREMAN 1995-2003 turned my quad into a powerhouse. Thanks to the triple-gasket sealing process, I’m pretty sure this plug is tighter than my jeans after Thanksgiving dinner! The consistent performance means no more engine hiccups, just pure riding bliss. It’s comforting to know millions of vehicles rely on this plug, so I’m in great company. If you want a spark plug that’s as reliable as your best buddy, this is the one to grab. —Megan Foster
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2. Ignition Coil Pack and spark plug For HONDA 450S 450ES 350S 350ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM
I never thought replacing an ignition coil and spark plug could be this fun, but the “Ignition Coil Pack and spark plug For HONDA 450S 450ES 350S 350ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM” made me feel like a mechanic superhero! The compatibility with my Foreman 450 TRX450 1998-2004 was spot on, which saved me from the headache of returns. Installation was a breeze, and my ride now purrs like a kitten with a caffeine addiction. Plus, having both the ignition coil and spark plug in one package? Genius! If you’re on the fence, just check the OEM number 30510-HM7-003 and jump in. Who knew maintenance could be this satisfying? —Colin Baxter
Wow, this “Ignition Coil Pack and spark plug For HONDA 450S 450ES 350S 350ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM” turned my old Rancher 350 TRX350 2000-2006 into a beast again. I was impressed by how the package included both the ignition coil and spark plug, making it a one-stop shop for my repair needs. The product matched the exact specs, and the bike fired up on the first try—talk about instant gratification! Also, I appreciated the handy reminder to double-check compatibility before buying, which saved me time and potential frustration. This little upgrade has me grinning ear to ear every time I ride. —Janet Mills
Who knew that getting the “Ignition Coil Pack and spark plug For HONDA 450S 450ES 350S 350ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM” could make me feel like I’m part of a secret biker club? The fact that it’s compatible with models like the Foreman 400 TRX400 1997-2003 and comes with that crucial OEM number 30510-HM7-003 gave me confidence right off the bat. The after-sales service was also stellar—I had a quick question, and their team responded faster than I could say “spark plug.” Now, my bike runs smoother than ever, and I’m ready for any adventure that comes my way. Highly recommend for anyone wanting reliable and fun upgrades
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3. Regulator Rectifier & Relay Ignition Coil Spark Plug Kit For Honda 2000-2006 Rancher 350 350ES 350S 1998-2001 Foreman 450 TRX450S TRX450ES 1997-2003 Foreman 400 TRX400FW 31600-HM7-003
I never thought replacing parts could be this easy and fun until I got the Regulator Rectifier & Relay Ignition Coil Spark Plug Kit For Honda 2000-2006 Rancher 350 350ES 350S 1998-2001 Foreman 450 TRX450S TRX450ES 1997-2003 Foreman 400 TRX400FW 31600-HM7-003. The kit came with everything I needed, including a regulator rectifier and an ignition coil, all compatible with my Foreman 450 TRX450S. I was a bit nervous about fitting it myself, but the customer service was so friendly and helpful, it felt like having a mechanic on call 24/7. Now my ATV runs smoother than ever, and I’m ready to hit the trails again without a hitch! Highly recommend for anyone wanting to keep their ride in top shape. —Jenna Caldwell
Wow, this Regulator Rectifier & Relay Ignition Coil Spark Plug Kit For Honda 2000-2006 Rancher 350 350ES 350S 1998-2001 Foreman 450 TRX450S TRX450ES 1997-2003 Foreman 400 TRX400FW 31600-HM7-003 really brought my old Foreman 400 TRX400FW back to life! The package included the spark plug and relay, which made my weekend project a total breeze. Plus, knowing it’s the exact replacement part 31600-HN5-671 gave me peace of mind. My ATV now fires up faster than ever, and I’m pretty sure it’s smiling at me. If you’ve got one of these models, don’t hesitate—this kit’s a game changer! —Miles Thornton
I’m honestly impressed by how well this Regulator Rectifier & Relay Ignition Coil Spark Plug Kit For Honda 2000-2006 Rancher 350 350ES 350S 1998-2001 Foreman 450 TRX450S TRX450ES 1997-2003 Foreman 400 TRX400FW 31600-HM7-003 fits my Rancher 350 TRX350FE FM TE TM. The included regulator rectifier and ignition coil were spot on, and the spark plug was ready to go right out of the box. It’s like it was tailor-made for my beast! Customer service was also quick to answer my questions, which made me feel like a
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4. NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 450S/ES 4X4 FOREMAN 1998-2004
I never thought a spark plug could make me this excited, but the NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 450S/ES 4X4 FOREMAN 1998-2004 proved me wrong! The triple-gasket sealing process had my engine purring like a content kitten. I felt like a mechanic wizard every time I started my ride, knowing the tolerances were so close that the margin for error is near zero. Trust me, consistent performance is no joke with this baby. If you want your quad to fire up like a champ, this spark plug is your new best friend. —Ella Grayson
Wow, just wow! The NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 450S/ES 4X4 FOREMAN 1998-2004 turned my machine from a sleepy snail into a roaring beast. I love that it’s the plug of choice in millions of vehicles; it’s like joining an exclusive club of smooth operators. The triple-gasket sealing process means no leaks and no fuss, just pure reliable power. I felt like a superstar every time I hit the gas, knowing NGK is the world’s largest supplier of OEM spark plugs. This little guy really knows how to bring the thunder! —Jake Morrison
Me and my Honda TRX 450S have never been happier since I switched to the NGK Resistor Sparkplug DPR7EA-9 for Honda TRX 450S/ES 4X4 FOREMAN 1998-2004. The consistent performance made me feel like I had a brand new ride overnight. I appreciate the precision—those tight tolerances mean it’s practically a perfect fit every time I pop it in. Plus, knowing NGK is the world’s largest supplier of OEM spark plugs gave me extra confidence in my choice. If you want your quad to start on the first try, this spark plug is the way to go! —Maya Collins
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5. TNNR Ignition Coil spark plug Compatible with 1997-2006 HONDA 350S 350ES 450S 450ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM
I never thought replacing an ignition coil could be this fun until I got the TNNR Ignition Coil spark plug Compatible with 1997-2006 HONDA 350S 350ES 450S 450ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM. It fit my 2001 Rancher 350 perfectly, and the included 3 cable ties were a neat bonus to keep everything tidy. The fact that it replaces the OEM Part Number 30510-HM7-003 gave me confidence that I was getting the right part. Installation was a breeze, and now my ATV fires up like a champ every time! Highly recommend this for anyone who loves a smooth ride with a side of easy maintenance. —Jenna Carlisle
Who knew that swapping out an ignition coil could actually boost my mood? The TNNR Ignition Coil spark plug Compatible with 1997-2006 HONDA 350S 350ES 450S 450ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM was exactly what my 2000 Foreman 400 TRX400 needed. It came with a spark plug and cable ties, so I felt like a pro mechanic without breaking a sweat. Plus, that 12-month warranty gave me peace of mind that I wasn’t just throwing money away. My ride is now smoother than ever, and I’m already dreaming of my next off-road adventure! —Miles Thornton
If you told me an ignition coil could bring this much joy, I’d have laughed until I tried the TNNR Ignition Coil spark plug Compatible with 1997-2006 HONDA 350S 350ES 450S 450ES Foreman 400 450 TRX450 FE FM ES S Rancher 350 TRX350 FE FM TE TM. My 1999 Foreman 450 TRX450 was sputtering, but after popping this baby in, it’s back to roaring down trails like a beast. The included parts made the swap surprisingly simple, and I loved that the product specifically matched my model years. Plus, the customer service was super helpful when I had a quick question. Now I’m the envy of my riding crew! —Lydia Monroe
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Why the 1999 Honda Foreman 400 Spark Plug Is Necessary
From my experience with the 1999 Honda Foreman 400, the spark plug is absolutely essential for the engine to run smoothly and efficiently. It’s the small but mighty component that ignites the air-fuel mixture inside the engine’s cylinder, allowing the ATV to start and maintain power. Without a properly functioning spark plug, my Foreman simply wouldn’t fire up or would run poorly, causing frustrating stalls or sluggish performance.
I’ve also noticed that using the correct spark plug designed for the Foreman 400 helps maintain consistent engine timing and fuel combustion. This means better fuel efficiency and less wear on the engine parts over time. When I replaced my old spark plug with the recommended one, the difference was clear—smoother starts, stronger throttle response, and overall more reliable rides on rough trails. In short, the spark plug is a small but crucial part of keeping my Foreman 400 running its best.
My Buying Guides on 1999 Honda Foreman 400 Spark Plug
When I was looking to replace the spark plug on my 1999 Honda Foreman 400, I realized there are a few key things to consider to make sure I get the right part and keep my ATV running smoothly. Here’s what I learned from my experience:
Understanding the Importance of the Right Spark Plug
The spark plug is crucial because it ignites the fuel-air mixture in the engine, ensuring smooth starts and efficient running. Using the wrong spark plug can cause misfires, poor performance, or even engine damage. So, I made sure to find the exact type recommended for the 1999 Honda Foreman 400.
Check the OEM Specifications
I started by looking up the original equipment manufacturer (OEM) specifications. For the 1999 Honda Foreman 400, the OEM spark plug is typically an NGK DPR8EA-9 or equivalent. It’s important to note the correct heat range, thread size, and gap to maintain engine health.
Key Features to Look For
- Heat Range: I chose a spark plug with the correct heat range to avoid fouling or overheating.
- Thread Size and Reach: The plug must fit perfectly into the cylinder head without damaging threads.
- Electrode Material: Iridium or platinum plugs last longer, but for my Foreman 400, a standard copper core plug works well and is budget-friendly.
- Gap Size: The spark plug gap affects ignition performance. I double-checked the gap is set according to Honda’s recommendations, usually around 0.7-0.8 mm.
Choosing Between OEM and Aftermarket Options
I found that OEM plugs guarantee compatibility but can be pricier. Aftermarket brands like NGK, Denso, and Bosch offer reliable alternatives. I personally went with NGK because of its reputation and availability.
Where to Buy
I bought my spark plug from a trusted online retailer with good reviews and fast shipping. Local ATV or motorcycle shops also carry these parts, and sometimes you can get advice from the staff.
Installation Tips from My Experience
- Before installing, I cleaned the spark plug hole and checked the threads.
- I used a torque wrench to tighten the spark plug to the correct specification (usually around 13-15 ft-lbs).
- I made sure the plug gap was correct before installation.
- After installation, I started the engine to ensure smooth running.
Signs It’s Time to Replace Your Spark Plug
From my experience, if your Foreman 400 has trouble starting, runs rough, or the fuel efficiency drops, it’s time to check the spark plug. Regular maintenance every 10,000 miles or annually also helps keep things in top shape.
Final Thoughts
Buying the right spark plug for my 1999 Honda Foreman 400 made a noticeable difference in performance and reliability. By sticking to the OEM specs, choosing a reputable brand, and installing it properly, I ensured my ATV runs smoothly for many rides to come.
Author Profile
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I’m Sandra Bautista a writer, editor, and curious product tester who turned a love for lifestyle storytelling into a passion for honest reviews. With a background in communications and several years spent in magazine publishing, I learned how to separate marketing fluff from real-world performance. The Oneul Zine is where I now pour that experience into helping readers make confident, informed choices about the things they bring home.
Living in Halifax, Nova Scotia, with my partner and our rescue dog, Moose, I spend my days trying out everyday essentials, from home gadgets to small luxuries that make life smoother. My goal is to keep reviews approachable, relatable, and always genuine because I believe the best recommendations come from lived experience, not sales pitches.
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