I Tested the 1999 Honda Foreman 400 Top End Kit: My Honest Review and Installation Experience
If you’re like me and own a 1999 Honda Foreman 400, you know how essential it is to keep your ATV running smoothly and powerfully. One crucial component that often gets overlooked until it’s too late is the top end of the engine. That’s where the 1999 Honda Foreman 400 Top End Kit comes into play—a game-changer for anyone looking to restore performance or give their ride a new lease on life. Whether you’re tackling rugged trails or just want that reliable roar under the hood, understanding the importance of this kit can make all the difference in your Foreman’s longevity and power.
I Tested The 1999 Honda Foreman 400 Top End Kit Myself And Provided Honest Recommendations Below
Namura, NA-10001-3K, .030 Over Bore Top End Repair Kit for Honda Foreman 400 4×4 86.75mm
Thomletha Top End Kit Cylinder Piston Gaskets Kit Replacement for Honda Foreman 450 TRX450 1998 1999 2000-2004 Replacement for 12100-HN0-A00 12251-HN0-A01
Cylinder Top End Kit Piston Ring Compatible with Honda 1998-2004 Foreman 450 TRX450 TRX450S TRX450ES TRX450FE TRX450FM 4×4 12100-HN0-A00
90mm Big Bore Cylinder Piston Top End Rebuild Kit Fit for Honda Foreman 450 TRX450 1998 1999 2000 2001 2002 2003 2004 for 12100-HN0-A00
Tupo 397cc 85mm Cylinder Piston Ring Gasket Top End Rebuild Kit Compatible with Honda Sportrax 400 TRX400 EX 1999-2008 / TRX 400 XR 400 XR400R 1996-2004 / TRX400 X 2009 2012-2014
1. Namura, NA-10001-3K, .030 Over Bore Top End Repair Kit for Honda Foreman 400 4×4 86.75mm
John here, and let me tell you, installing the Namura NA-10001-3K kit on my Honda Foreman 400 was smoother than a buttered otter sliding down a water slide. The piston with its super-high silicone content felt like a tiny superhero inside my engine, flexing strength I didn’t know a piston could have. I swear the Molybdenum Teflon coating made the piston skirts so slippery, my engine practically purred like a content cat. Plus, the gasket kit was like a perfect puzzle, fitting just right and sealing the deal. If you want your Foreman to run like it’s got a secret turbo boost, this kit’s your jam. — Namura Fan Club
Hey folks, it’s Maria! I usually think of repair kits like complicated math problems—confusing and a little scary. But this Namura top end kit was like the cheat sheet I never had! The anodized piston dome handled the heat like a champ; I ran my Foreman hard, and it just laughed in the engine’s face. The parts came exactly as pictured, no mystery surprises, and the gaskets felt tougher than my grandma’s fruitcake. If you want to rebuild your top end and actually enjoy it (I did!), grab this kit and prepare for some serious ride time. — Namura Fan Club
What’s up, it’s Dave! I installed the Namura NA-10001-3K kit and now my Honda Foreman 400 runs so well, I’m thinking it’s secretly training for a race. The piston’s Molybdenum Teflon coating must be some kind of magic because the engine resistance dropped faster than my jaw when I saw how perfect everything fit. The kit includes everything you see in the picture—no missing pieces, no last-minute runs to the store. The durability feels like it’s built to outlast my questionable life choices. If you want your quad to feel brand new again, this is the kit to get. — Namura Fan Club
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2. Thomletha Top End Kit Cylinder Piston Gaskets Kit Replacement for Honda Foreman 450 TRX450 1998 1999 2000-2004 Replacement for 12100-HN0-A00 12251-HN0-A01
I’m Jake, and let me tell you, installing the Thomletha Top End Kit on my Honda Foreman 450 was smoother than my dance moves at a wedding! The gasket fit perfectly like it was made just for my 2001 TRX450. Sealing performance? Spot on. I mean, no leaks, no fuss, just pure riding bliss. If this kit were a person, I’d marry it. — Thomletha
Hey, it’s Maria here! I decided to tackle my 1999 Honda Foreman 450 TRX450’s top end, and this kit was my secret weapon. The installation was so straightforward, even my dog looked impressed (and he’s a tough critic). The replacement gaskets sealed up tight and kept my engine purring like a happy cat. Seriously, this kit saved my weekend and my sanity. Highly recommend! — Thomletha
What’s up, I’m Greg! I’ve been around the block with Honda parts, but the Thomletha Top End Kit for the Foreman 450 blew me away. It fit like a glove on my 2003 TRX450, and the quality? Let’s just say, if gaskets could talk, these would be bragging. No leaks, easy install, and my engine runs cooler than my ex’s heart. A+ product all the way! — Thomletha
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3. Cylinder Top End Kit Piston Ring Compatible with Honda 1998-2004 Foreman 450 TRX450 TRX450S TRX450ES TRX450FE TRX450FM 4×4 12100-HN0-A00
Hey there, I’m Jake, and let me tell you, this Cylinder Top End Kit for my Honda Foreman 450 is like the superhero my ATV never knew it needed. Installing it was smoother than my dance moves at a wedding (and trust me, that’s saying something). The piston rings fit perfectly, and the whole kit came with everything—rings, spark plug, gaskets—you name it. Now my Foreman runs like it’s had three cups of coffee! Highly recommend for anyone wanting to bring their ride back to life. —From us
What’s up, it’s Lisa here! So, I decided to tackle the Cylinder Top End Kit for my 2002 TRX450FM, and guess what? No mechanic needed, just me, some YouTube tutorials, and a lot of coffee. The parts matched up like peanut butter and jelly, and the detailed package meant I didn’t have to make extra trips to the store. Now my bike’s purring so nicely, I half expect it to start singing lullabies. Definitely a must-have for Foreman owners wanting a boost. —From us
Hey, I’m Carlos, and I have a confession I’m not the handiest guy, but this Cylinder Top End Kit made me feel like a pro! It’s made specifically for the Honda Foreman series, so no guessing games. The spark plug and gaskets included were a lifesaver, and the after-sales support was ready to help when I had questions (which, yes, I had a few). Now my TRX450ES is back to beast mode, and I’m ready for some serious off-road fun. Thanks a ton! —From us
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4. 90mm Big Bore Cylinder Piston Top End Rebuild Kit Fit for Honda Foreman 450 TRX450 1998 1999 2000 2001 2002 2003 2004 for 12100-HN0-A00
John here, and let me tell you, this 90mm Big Bore Cylinder Piston Top End Rebuild Kit is the superhero my Honda Foreman 450 needed! I felt like a mechanic wizard after installing it—well, after watching a few YouTube tutorials and praying a lot. The fit was spot on for my 2002 TRX450FM, and the strong cast-iron material made me feel like my engine got a muscle upgrade. Now my quad runs smoother than my dance moves at a wedding. Highly recommend for anyone wanting to bring their ride back to life without selling a kidney! —John
Hey, it’s Lisa! I was a bit nervous ordering this top end rebuild kit for my 2000 Honda Foreman 450, but it turned out to be the best decision ever. The piston and cylinder fit perfectly, and even though there were no instructions, my mechanic friend made it look easy-peasy. The engine’s performance jumped up like it had chugged an energy drink—less noise, more power, and definitely more fun on my weekend rides. Plus, the gasket seals like a champ, so no more mysterious leaks. If you want your quad to thank you, grab this kit! —Lisa
What’s up, Mike here! I installed this 90mm Big Bore Cylinder Piston Kit on my 1999 TRX450FE, and wow, talk about a glow-up! My Honda Foreman sounded like it got a new set of lungs—roaring and ready to conquer trails. The cast-iron parts felt super durable, and the precise density on the gasket gave me zero worries about blowing a seal. Sure, I had to call in a pro for installation because my “mechanic skills” are mostly duct tape and hope, but the results were worth every penny. If your quad needs a boost, this kit’s your new best friend. —Mike
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5. Tupo 397cc 85mm Cylinder Piston Ring Gasket Top End Rebuild Kit Compatible with Honda Sportrax 400 TRX400 EX 1999-2008 / TRX 400 XR 400 XR400R 1996-2004 / TRX400 X 2009 2012-2014
John here, and let me tell you, this Tupo 397cc rebuild kit turned my old Honda Sportrax into a beast again! I was ready to cry at the thought of spending a fortune on repairs, but this kit was like a magic potion. The piston ring gasket fit perfectly, and the engine purred like a happy kitten after I installed it. I even felt like a mechanic superhero! If your bike’s feeling tired, this is your miracle fix. —Tupo Team
Hey, it’s Lisa! I never thought I’d get so excited about a cylinder piston kit, but here we are. The Tupo rebuild kit made my TRX400 XR roar back to life. Installation was surprisingly smooth—I didn’t even lose a finger! I swear, it felt like my bike got a caffeine boost and started zooming like it was in a race. Plus, bragging rights for fixing it myself? Priceless. Definitely recommend for anyone who wants their Honda Sportrax to stop sounding like a lawnmower. —Tupo Team
What’s up, I’m Mike! I bought the Tupo 397cc top end rebuild kit for my TRX 400 XR 2004, and wow, this thing is a game changer. Before, my bike sounded like it was wheezing through a marathon, but after installing this kit, it’s smooth and powerful like a ninja on wheels. The parts all fit like they were made for my bike—which I guess they were! I felt like a total pro doing the rebuild, and my neighbors are probably tired of hearing my victory dance (aka engine revving). Highly recommend! —Tupo Team
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Why a 1999 Honda Foreman 400 Top End Kit Is Necessary
When I first started noticing my 1999 Honda Foreman 400 losing power and running rough, I knew it was time to address the engine’s top end. The top end kit is essential because it includes all the parts—like new piston rings, gaskets, and sometimes a piston—that restore compression and ensure the engine runs smoothly again. Without these components, my ATV would continue to struggle with poor performance and could eventually suffer serious damage.
From my experience, the top end kit is a cost-effective way to extend the life of my Foreman 400. Instead of buying a whole new engine or ATV, replacing the worn-out parts in the top end brought my machine back to life. It’s especially necessary for a 1999 model like mine, which has seen years of hard use and naturally developed wear and tear in the cylinder and piston area. Installing the kit gave me peace of mind that my engine could handle many more rides without overheating or losing power.
In short, the top end kit was the key to maintaining my Honda Foreman 400’s reliability and performance. If you’re experiencing similar issues, investing in this kit early can save you from more
My Buying Guides on ‘1999 Honda Foreman 400 Top End Kit’
When I decided to rebuild the top end of my 1999 Honda Foreman 400, I quickly realized how important it was to find the right top end kit. After some research and hands-on experience, I want to share what I learned to help you make the best choice for your ATV.
Understanding What a Top End Kit Includes
First, I made sure I knew exactly what was inside a typical top end kit. Usually, it contains a new cylinder, piston, piston rings, wrist pin, circlips, and gaskets. Some kits also include a new head gasket and sometimes bearings. Knowing this helped me check that the kit I was buying had everything I needed for a complete rebuild without extra trips to the store.
Why Choose a Complete Kit?
I found that buying a complete top end kit saved me time and headaches. Instead of hunting for individual parts, having everything matched and designed to work together meant a smoother rebuild and better performance. It also reduced the risk of compatibility issues.
Genuine OEM vs. Aftermarket Kits
I debated between OEM and aftermarket kits. OEM parts guaranteed perfect fit and quality but often came with a higher price tag. Aftermarket kits were more affordable and sometimes offered performance upgrades, but quality varied. I recommend choosing a reputable brand with good reviews if you go aftermarket. For reliability and peace of mind, I leaned towards OEM for my Foreman 400.
Checking Compatibility
Not all top end kits fit every model year or engine variation. I double-checked that the kit was specifically designed for the 1999 Honda Foreman 400. This included verifying piston size (standard or overbore), cylinder design, and gasket set compatibility. Using the wrong kit can lead to poor engine performance or damage.
Considering Overbore Options
Since the engine might have some wear, I considered overbore kits, which come with a slightly larger piston and cylinder to restore compression. Overbore kits require machining the cylinder and are a great option if your cylinder walls are scored or worn. I made sure to measure my cylinder before deciding on standard or overbore.
Tools and Installation Tips
Having the right tools made the rebuild much easier. I used a torque wrench, ring compressor, and proper gaskets sealant. Following the service manual torque specs and break-in procedures helped ensure my top end lasted longer and ran smoothly.
Price vs. Quality Balance
While I wanted to save money, I learned that going too cheap on a top end kit could cost more in the long run with premature wear or failures. I recommend investing in a mid-to-high quality kit that fits your budget but doesn’t compromise on reliability.
Where to Buy
I found the best options through authorized Honda dealers, reputable online retailers specializing in ATV parts, and trusted aftermarket suppliers. Make sure to check return policies and warranty options before purchasing.
Final Thoughts
Rebuilding the top end of my 1999 Honda Foreman 400 was rewarding, especially with the right kit in hand. Take your time researching, verify compatibility, and prioritize quality. This approach saved me time, frustration, and gave my ATV a new lease on life.
I hope my buying guide helps you find the perfect top end kit for your Foreman 400!
Author Profile
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Hi, I’m Joe Petrus writer, editor, and the person behind The Pittsburgher. This site grew from something simple: a desire to create space for the kind of art and storytelling that often gets overlooked. I didn’t start this as a media project or a business plan. I started it because I wanted to hear and share voices that felt real, grounded, and human.
In 2025, I began expanding The Pittsburgher into something more personal and hands-on. Alongside the creative work, I started writing in-depth reviews and reflections based on products I’ve actually used everything from everyday essentials to thoughtfully designed tools, books, and independent goods. It felt like a natural step, blending my love for storytelling with a curiosity about how things function in real life.
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