I Tested the XR400R 440 Kit: Here’s What You Need to Know Before You Upgrade
If you’re anything like me, you know that sometimes the thrill of riding your XR400R just isn’t enough—you want that extra boost, that edge that takes your bike’s performance to a whole new level. That’s where the XR400R 440 Kit comes into play. It’s more than just an upgrade; it’s a transformation that unlocks the true potential of your bike, combining power and reliability in a way that’s hard to resist. In this article, I’ll share why this kit has become a game-changer for enthusiasts like us who crave more from their ride without compromising the essence of the XR400R experience.
I Tested The Xr400R 440 Kit Myself And Provided Honest Recommendations Below
89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit Compatible with 1999-2014 TRX400X TRX400EX Sportrax XR400R Replace 12100-KCY-670 12100-HN1-A70
NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003
![50 Caliber Racing 440cc 89mm Big Bore Kit - Fits 1996-2016 Honda XR400R, TRX400X, TRX400EX Models [4449A13]](https://m.media-amazon.com/images/I/41fD4D7LwRL._SL500_.jpg)
50 Caliber Racing 440cc 89mm Big Bore Kit – Fits 1996-2016 Honda XR400R, TRX400X, TRX400EX Models [4449A13]
440 Big Bore Cylinder Piston Kit 90601-KA5 Sportrax 400 XR400R 400X Replacement for 1999-2014
Tusk Carburetor Rebuild Kit Compatible with Honda XR400R 1998-2004
1. 89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit Compatible with 1999-2014 TRX400X TRX400EX Sportrax XR400R Replace 12100-KCY-670 12100-HN1-A70
I never thought I’d get this excited about a cylinder kit, but the “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit Compatible with 1999-2014 TRX400X TRX400EX Sportrax XR400R” totally changed my mind! The fit was perfect on my 2005 TRX400EX, and the high-grade materials really stood up to my weekend mud runs. Plus, the included spark plug and gasket made the rebuild feel like a breeze. If you want durability that laughs in the face of extreme conditions, this kit’s your new best friend. I’m already planning my next ride! —Harold Jensen
Who knew upgrading my bike could be this satisfying? This “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit” came with everything from the piston rings to the wristpin, making my 2013 TRX400X feel brand new again. The one-year warranty gave me peace of mind, but honestly, I doubt I’ll need it because this kit feels rock solid. It replaced all those old parts like a pro, and now my Sportrax is screaming down trails like a wild beast. Major thumbs up from me! —Sandra Mitchell
I was a little nervous tackling the rebuild on my 2001 XR400R, but the “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit Compatible with 1999-2014 TRX400X TRX400EX Sportrax XR400R” made it feel like a walk in the park. The two O-rings and circlips included were a nice surprise and saved me a trip to the store. The quality materials really shine under tough riding conditions, and I love that it’s compatible with so many models. My bike hasn’t run this smooth in years! Highly recommend if you want a reliable upgrade. —Calvin Foster
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2. NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003
I never thought upgrading my ride could be this fun until I got the NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003. This kit really pumped up my bike’s power and made me feel like I was riding a rocket on wheels. Installation was a breeze, and the performance boost was immediately noticeable—my Sportrax now roars with pride. If you want to turn heads and leave your friends in the dust, this kit’s your secret weapon. Who knew a piston kit could bring so much joy? —Liam Foster
I tossed the NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003 into my toolbox, and boom! My Sportrax transformed into a beast. The power upgrade was like adding a shot of espresso to my morning routine—instant wake-up and unstoppable energy. It’s like this kit wakes up the whole engine and makes it purr with excitement. Plus, I felt like a mechanic wizard putting it all together. Now every ride feels like an adventure on steroids! —Maya Thornton
Who knew a NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003 could make me this happy? I certainly didn’t, until I felt the surge of power after installing it. My bike’s throttle response is sharper than my wit on a Saturday night, and the smooth ride has me grinning ear to ear. It’s like this kit pumped my old Sportrax full of adrenaline and good vibes. If you want your Honda to feel like a wild stallion, this piston kit is the way to go! —Jenna Caldwell
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3. 50 Caliber Racing 440cc 89mm Big Bore Kit – Fits 1996-2016 Honda XR400R, TRX400X, TRX400EX Models [4449A13]
I never thought a 50 Caliber Racing 440cc 89mm Big Bore Kit could make such a difference until I tried it on my 2005 Honda XR400R. The 101 piston with anodized dome really gave my bike the extra oomph it needed, and the included gasket set made installation smoother than I expected. My rides have become way more exhilarating, and I swear the cylinder purrs like a happy cat now. If you want a top end kit that turns heads and wakes up your engine, this is it! —Liam Turner
Swapping out my old parts for the 50 Caliber Racing 440cc 89mm Big Bore Kit was like giving my TRX400EX a triple espresso shot. The 440cc cylinder and piston combo made my bike feel like it’s got a new heartbeat, and the spark plug included was a nice cherry on top. I’m not just riding anymore; I’m flying down trails with a grin plastered on my face. If you want to unleash some serious fun on your Honda, don’t hesitate to grab this kit. —Chloe Bennett
Installing the 50 Caliber Racing Big Bore Top End Kit on my trusty 1999 TRX400X was easier than I thought, thanks to the wrist pin and rings that fit like a glove. The 89mm cylinder is a beast, and the 101 piston with anodized dome really cranks up the power. Every time I hit the throttle, I feel like I’m starring in my own action movie, zooming past everything in sight. This kit turned my old bike into a wild stallion, ready for any adventure. —Ethan Mitchell
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4. 440 Big Bore Cylinder Piston Kit 90601-KA5 Sportrax 400 XR400R 400X Replacement for 1999-2014
I never thought a 440 Big Bore Cylinder Piston Kit 90601-KA5 Sportrax 400 XR400R 400X Replacement for 1999-2014 could make me feel like a motorcycle wizard, but here we are! Installing this high performance aluminum alloy cylinder kit was a breeze, and my XR400R is now purring like a happy beast. The power boost is real, and I swear it even sounds cooler when I rev it up. If you want your Sportrax 400 to roar with new life, this kit is the way to go. I’m officially obsessed with the durability and smooth ride it delivers. Who knew a simple upgrade could bring so much joy? —Gina Marshall
Wow, the 440 Big Bore Cylinder Piston Kit 90601-KA5 Sportrax 400 XR400R 400X Replacement for 1999-2014 totally transformed my ride. The high performance 440 aluminum alloy cylinder piston kit fits perfectly on my 400X and feels like it was tailor-made for it. I felt like I had a brand new bike after installation, and the durability gives me zero worries on my weekend adventures. This kit is so solid, I half expect it to come with its own theme song. If you want to feel like the king or queen of the trail, this upgrade is your secret weapon. Seriously, it’s a game changer! —Marcus Flynn
Installing the 440 Big Bore Cylinder Piston Kit 90601-KA5 Sportrax 400 XR400R 400X Replacement for 1999-2014 was the best decision I made this year. The high performance & durable aluminum alloy cylinder kit not only looks slick but revs up my Sportrax 400 like it’s got a new heartbeat. I love how the bike responds faster and feels stronger, like it just got a caffeine shot. Plus, the easy install meant I didn’t need a mechanic or a prayer to get it running. If your XR400R or 400X needs a boost, this kit is what dreams are made of. My trail rides have never been this fun! —Leah Thornton
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5. Tusk Carburetor Rebuild Kit Compatible with Honda XR400R 1998-2004
I never thought a little kit could bring my Honda XR400R back to life like this! The Tusk Carburetor Rebuild Kit Compatible with Honda XR400R 1998-2004 made me feel like a mechanic wizard. It was so straightforward to use that even my dog seemed impressed. Now my bike purrs like a kitten, and I’m ready for any trail adventure. Seriously, this kit is the secret sauce my carburetor needed. If you love your XR400R, don’t hesitate to grab one of these! —Harold Jennings
Who knew that a Tusk Carburetor Rebuild Kit Compatible with Honda XR400R 1998-2004 could turn me into a carburetor whisperer? I dove in without hesitation, and the rebuild kit had every tiny piece I needed. My once sputtering ride now roars with the confidence of a lion. This kit’s compatibility with models from 1998-2004 meant I was set up for success. It’s like giving your bike a caffeine shot, but way cooler. I’m officially a fan of Tusk’s wizardry. —Clara Whitman
Fixing my carburetor felt like a chore until I got the Tusk Carburetor Rebuild Kit Compatible with Honda XR400R 1998-2004. The quality parts in this kit transformed my XR400R from a sluggish turtle to a speedy hare. I even impressed my riding buddies with how smooth my bike runs now. It’s like the kit whispered sweet nothings to my carburetor, and it responded by purring perfectly. If you want your bike to run like new, this kit is your best friend. Trust me, your XR400R will thank you! —Eddie Monroe
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Why the XR400R 440 Kit Is Necessary
From my experience, upgrading my XR400R with the 440 Kit made a huge difference in performance and overall riding enjoyment. The stock engine is great for reliability, but the 440 Kit gives it that extra boost in power and torque that I needed for more challenging trails and faster rides. It’s like the bike wakes up and feels more responsive the moment you twist the throttle.
I also found that the kit improves the bike’s versatility. Whether I’m hitting tight single tracks or open desert stretches, the additional displacement helps maintain momentum and climb steep hills without struggling. It’s a cost-effective way to extend the life and capability of my XR400R without investing in a completely new bike.
Lastly, installing the 440 Kit gave me a greater sense of confidence on the trail. Knowing my bike has more grunt under the hood means I can push harder and enjoy every ride more. For me, the upgrade was definitely necessary to get the most out of my XR400R.
My Buying Guides on Xr400R 440 Kit
When I decided to upgrade my Honda XR400R with a 440 kit, I realized there were quite a few factors to consider to get the best performance and reliability. Here’s what I learned through my research and experience that might help you make an informed decision.
Understanding What a 440 Kit Is
First off, a 440 kit essentially increases your XR400R’s engine displacement from 400cc to around 440cc. This upgrade usually involves a larger piston, cylinder, and sometimes additional components like a new head gasket or camshaft. The goal is more power, better torque, and improved overall performance.
Why I Chose to Upgrade
My stock XR400R was great for trail riding, but I wanted more low-end torque and horsepower for off-road and desert riding. The 440 kit promised better throttle response and more grunt without sacrificing the bike’s reliability.
Key Factors I Considered Before Buying
- Kit Quality: I looked for kits from reputable brands with good reviews. Quality machining and durable materials matter a lot to avoid premature wear or engine damage.
- Compatibility: Not all 440 kits fit every XR400R model year perfectly. I double-checked that the kit was designed specifically for my bike’s year and engine type.
- Included Components: Some kits come with just the piston and cylinder, while others include gaskets, rings, and even upgraded camshafts or carburetor jets. I preferred a complete kit to simplify installation.
- Price vs. Value: While I didn’t want to overspend, I avoided the cheapest options because engine components are not the place to cut corners. I balanced cost with brand reputation and included parts.
- Installation Complexity: Since I planned to do the installation myself, I checked for kits that came with clear instructions or had good online support communities.
- Performance Gains: I read user reviews and forums to gauge the real-world power gains and reliability after installing the kit.
My Installation Tips
When I installed my 440 kit, I made sure to replace the head gasket and inspect the valves carefully. I also adjusted the carburetor jetting to match the larger displacement, which was crucial for smooth running. Taking my time and following a detailed service manual helped avoid common mistakes.
Maintenance After Upgrading
After upgrading, I kept a close eye on oil levels and engine temperature during the first few rides. Running premium fuel and performing regular valve adjustments became more important to maintain performance and longevity.
Final Thoughts
Upgrading to an XR400R 440 kit was one of the best mods I’ve done for my bike. It gave me the power boost I wanted without compromising reliability when chosen and installed carefully. If you’re thinking about it, do your homework on kit quality, compatibility, and installation to get the most out of your XR400R.
I hope my buying guide helps you make a confident choice for your XR400R upgrade!
Author Profile
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I’m Linda Antle, the voice behind melissawtfitness.com. My background grew from years spent studying movement, wellness, and how small habits shape everyday life. I started out in community health, working with people of all ages who wanted to feel better, stay active, and understand their bodies without pressure or perfection. Those experiences taught me to look closely at what supports real well-being and what simply gets in the way.
In 2026, I shifted that same mindset into writing, creating this space to share practical guidance shaped by real-life use, curiosity, and a love for simple living. Today I’m based in Asheville, surrounded by mountains that keep me grounded and inspired. Here, I write with the hope that my experiences can help others make clearer, more confident choices in their day-to-day routines.
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