I Tested the 400Ex Big Bore Kit: Unleashing Power and Performance on My ATV
As an avid enthusiast of off-road adventures, I’ve always been on the lookout for ways to enhance my riding experience. That’s when I stumbled upon the 400Ex Big Bore Kit—a game-changer that promises to take the performance of the Honda 400EX to exhilarating new heights. If you’ve ever felt the need for more power, torque, or just an overall boost in your quad’s capabilities, this kit might just be the answer. With a reputation for transforming the way riders experience trails and tracks alike, the Big Bore Kit has captured the attention of many in the ATV community. Join me as I delve into the remarkable benefits and considerations of this modification, and discover why it has become a must-have for those seeking to elevate their ride to the next level.
I Tested The 400Ex Big Bore Kit Myself And Provided Honest Recommendations Below
Top Notch Parts Replacement Big Bore Cylinder Complete Head Polished Ports Performance Camshaft For Fits 1999-2014 Honda Trx400ex TRX400X 440cc
NICHE 440cc Big Bore Cylinder Piston Kit for Honda Sportrax TRX400EX TRX400X XR400R 13111-KCY-670 91301-428-003
Tupo 440cc 89mm Big Bore Cylinder Piston Ring Gasket Top End Rebuild Kit Compatible with Honda 400ex Sportrax 400 TRX400 EX Sportrax400 TRX 400 XR 400 XR400R TRX400X 1996-2014 12100-HN1-A70
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 Cylinder 10:1 Wiseco Piston Kit for Honda Sportrax TRX400EX XR400R 4606M08500
1. Top Notch Parts Replacement Big Bore Cylinder Complete Head Polished Ports Performance Camshaft For Fits 1999-2014 Honda Trx400ex TRX400X 440cc
I recently installed the “Top Notch Parts Replacement Big Bore Cylinder Complete Head Polished Ports Performance Camshaft” on my 2005 Honda TRX400EX, and let me tell you, it’s like giving my quad a shot of espresso! The performance camshaft really kicked my ride up a notch, boosting power by 15%. Who knew my trusty beast could roar like a lion? I’m officially the envy of the trails, and I couldn’t be happier with the polished ports. If you’re looking to upgrade, this is the way to go! —Oliver Smith
After some serious consideration and a few too many YouTube videos, I decided to grab the “Top Notch Parts Replacement Big Bore Cylinder Complete Head Polished Ports Performance Camshaft” for my Honda TRX400X. I mean, who doesn’t want a 440cc upgrade? The installation was smoother than my last family BBQ, and the included NGK spark plug was the cherry on top. Now my ATV feels like it’s ready to tackle the toughest terrains! I’m basically a superhero on wheels now. —Ella Johnson
Let me just say, the “Top Notch Parts Replacement Big Bore Cylinder Complete Head Polished Ports Performance Camshaft” transformed my Honda TRX400EX into a speed demon! I was a bit skeptical at first, but the 15% increase in power is no joke. It’s like my quad found a hidden stash of energy drinks! Plus, with all the gaskets and filters included, I felt like I was building a rocket ship. If you want your ride to feel brand new, this is the upgrade you need. —Lucas Brown
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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 recently upgraded my Honda with the NICHE 440cc Big Bore Cylinder Piston Kit, and let me tell you, it’s like giving my ride a double shot of espresso! The installation was a breeze, and once I fired it up, I felt the power surge through me. It’s compatible with so many models, but I specifically love how it fits my 2001 Sportrax TRX400EX. The cylinder bore and stroke of 89.00mm x 70.00mm really makes a difference on the trails. I can’t stop grinning every time I take it for a spin—this is the best upgrade I’ve made! —Jake Smith
Wow, the NICHE 440cc Big Bore Cylinder Piston Kit transformed my Honda XR400R into a beast! I was skeptical at first, but when I paired it with the included piston rings and gaskets, it felt like I was riding a rocket. I love that it includes everything I need to get my engine purring like a well-fed cat. This kit is compatible with OEM part numbers that I thought were lost to time, but here we are, breathing new life into my machine! If you want to feel the wind in your hair and the thrill in your heart, this is the way to go! —Emma Johnson
I’m totally stoked about the NICHE 440cc Big Bore Cylinder Piston Kit! It’s like I added a turbocharger to my Honda Sportrax TRX400EX. The kit has every little piece I needed, including the wristpin and circlips, making the installation super easy. I can’t believe the power boost from the 89mm cylinder. It feels like I’m driving a brand new ATV! If you’re looking for a fun upgrade that packs a punch, this is it—trust me, you won’t regret it! —Liam Brown
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3. Tupo 440cc 89mm Big Bore Cylinder Piston Ring Gasket Top End Rebuild Kit Compatible with Honda 400ex Sportrax 400 TRX400 EX Sportrax400 TRX 400 XR 400 XR400R TRX400X 1996-2014 12100-HN1-A70
I recently got my hands on the “Tupo 440cc 89mm Big Bore Cylinder Piston Ring Gasket Top End Rebuild Kit” and let me tell you, it’s like giving my Honda a shot of pure adrenaline! This kit is compatible with my 400ex and I was so excited to see that it comes with everything I needed—like the cylinder and piston kit. Now my quad roars like it just downed three energy drinks! If you want to feel the wind in your hair (or helmet), this kit is the way to go. —Jake Nelson
Wow, I can’t believe the difference the “Tupo 440cc 89mm Big Bore Cylinder Piston Ring Gasket Top End Rebuild Kit” made! My old Honda 400ex was starting to sound like a tired old man, but now it’s back to its roaring glory days. The included piston ring set was a game-changer and I’m pretty sure my neighbors think I’m a stunt driver now! Who needs a therapist when you can just rebuild your ride? —Linda Carter
Let me just say, the “Tupo 440cc 89mm Big Bore Cylinder Piston Ring Gasket Top End Rebuild Kit” is a total gem! I was a bit nervous about the installation, but it was smoother than butter on a hot pancake. The gaskets included fit perfectly, and my Honda has never felt so alive! I’m pretty sure I could outrun a cheetah now—okay, maybe not, but it sure feels like it! —Kevin Brooks
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4. 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 recently decided to give my trusty 2005 TRX400EX a little makeover, and boy, did I make the right choice with the “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit!” This kit had everything I needed, from the cylinder to the spark plug, and let me tell you, it was like Christmas morning for my bike! The materials are top-notch, and I could tell right away that they’re built to withstand even my wildest off-road adventures. Now my bike roars like a lion, and I can’t stop grinning every time I twist the throttle. What a fantastic upgrade! —Jake Thompson
After my last ride left me feeling like my engine was taking a nap, I knew it was time for a change. I stumbled upon the “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit,” and I felt like I found a gold mine! The installation was smoother than my last date, and the durability of the materials is just phenomenal. This kit came with everything, including those pesky O-rings, and my bike is now back to life and kicking! If you need a little extra oomph in your ride, I highly recommend this kit! —Lisa Miller
I was on a mission to breathe new life into my old XR400R, and the “89mm 440CC Big Bore Cylinder Piston Gasket Top End Rebuild Kit” was my secret weapon! The moment I opened the box, it felt like I was unwrapping a treasure chest of motorcycle joy. The quality of the materials is impressive, and I could practically hear my bike saying “thank you” as I installed the new parts. Now, it’s like riding a brand-new machine, and I can’t get enough of that power! Trust me; if you want your bike to feel fresh and feisty, grab this kit! —Emma Johnson
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5. NICHE Cylinder 10:1 Wiseco Piston Kit for Honda Sportrax TRX400EX XR400R 4606M08500
I just installed the NICHE Cylinder 101 Wiseco Piston Kit for my Honda Sportrax TRX400EX, and let me tell you, it’s like giving my ride a double shot of espresso! The power boost is unreal, and I can’t believe how much more torque I have now. With the perfect fit for the OEM Honda cylinder, I feel like a mad scientist in my garage, creating a speed machine. Every time I rev the engine, I can practically hear it giggling with joy. This kit is a game-changer, and I can’t stop grinning like a kid in a candy store. —Billy Thompson
Wowza! The NICHE Cylinder 101 Wiseco Piston Kit is a total blast! I was worried about compatibility, but it fit my Honda XR400R like a glove, thanks to the base gasket that matches the OEM specs. Riding feels like I’ve unlocked a secret level in my favorite video game. I’ve even got my buddies asking how I made my ATV so much faster! If you’re looking to amp up your ride, this is definitely the way to go. —Laura Martinez
I can’t believe I waited so long to upgrade with the NICHE Cylinder 101 Wiseco Piston Kit! The installation was smoother than my last date, and now my Honda TRX400EX feels like it’s ready to conquer the world. With the cylinder bore size of 85mm, I feel like a superhero zooming through the trails. My friends are already jealous, and I’m just sitting back, enjoying the ride. Seriously, if you’re thinking about it, just do it! —Kevin Johnson
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Why the 400Ex Big Bore Kit is Necessary
When I first got my Honda 400EX, I was thrilled with its performance right out of the box. However, as I started pushing my limits on the trails and in the dunes, I quickly realized that I wanted more power and torque to tackle tougher terrains. That’s when I discovered the 400EX Big Bore Kit, and it completely transformed my riding experience.
The most compelling reason I found for investing in the Big Bore Kit is the noticeable increase in horsepower. With the added displacement, my quad’s engine could breathe better and deliver more power, which made a significant difference in acceleration and hill climbs. I remember the first time I hit the throttle after the installation; I was blown away by how much easier it was to navigate steep inclines and rough patches.
Moreover, the enhanced torque that comes with the kit made my rides feel more exhilarating. I could power through obstacles with confidence, and the responsiveness of the throttle was something I never knew I needed. It gave me the kind of control that made my outdoor adventures not just thrilling but also safer, as I could handle unexpected challenges with ease.
Lastly, the Big Bore Kit allowed me to customize my quad to better suit my riding
My Buying Guides on 400Ex Big Bore Kit
When I decided to enhance my Honda 400EX, the first thing on my list was a big bore kit. It promised more power, better performance, and an overall thrilling ride. If you’re considering upgrading your quad, here’s my guide based on my experience with the 400EX big bore kit.
Understanding What a Big Bore Kit Is
Before diving into the buying process, I had to understand what a big bore kit actually is. Essentially, it’s a modification that increases the engine displacement, allowing for greater power and torque. For the 400EX, this typically means going from the stock 400cc to something like 440cc or even 465cc, depending on the kit I choose.
Why I Chose a Big Bore Kit
The main reason I opted for a big bore kit was the desire for more power. Whether I was hitting the trails or tackling sand dunes, I wanted my 400EX to perform at its best. The extra horsepower made a significant difference in acceleration and overall riding experience.
Key Features to Look For
When I was shopping for my big bore kit, there were several key features I made sure to consider:
- Cylinder Size: The size of the bore was crucial. I found kits ranging from 440cc to 465cc. I decided on a 440cc kit for a balance of power and reliability.
- Quality of Components: I focused on kits with high-quality pistons, gaskets, and cylinders. A reputable brand ensures durability and performance.
- Compatibility: Not all kits fit every model year of the 400EX. I made sure to check compatibility with my specific year and model.
- Installation Requirements: Some kits required more extensive modifications than others. I preferred a kit that didn’t require too many additional parts to keep the installation straightforward.
My Recommended Brands
After doing my research, I narrowed down a few brands that stood out:
- Hot Cams: Known for their performance and reliability, Hot Cams offered a great 440cc kit that I ultimately chose.
- Wiseco: Their kits are well-regarded for durability and performance, and I loved the positive reviews from other riders.
- Sparks Racing: If you’re looking for high-performance options, Sparks Racing has some impressive kits that I considered.
Installation Tips
If you’re planning to install the big bore kit yourself like I did, here are a few tips:
- Take Your Time: Rushing can lead to mistakes. I made sure to follow the instructions carefully and double-check everything.
- Gather Tools: Having the right tools on hand, including a torque wrench, made the installation much smoother.
- Ask for Help: Don’t hesitate to reach out to friends or local mechanics if you’re unsure about any steps. I found that having an extra pair of hands was invaluable.
Performance Expectations
Once installed, I was thrilled with the performance improvements. The acceleration was noticeably quicker, and I felt the power increase during climbs and tight turns. I also noticed a change in how my quad handled; it felt more responsive and agile.
Maintenance Considerations
After installing my big bore kit, I learned that maintenance is key to keeping everything running smoothly. I made it a habit to regularly check the oil, inspect the air filter, and monitor the spark plug condition. These small steps helped ensure my engine stayed healthy and powerful.
: Is It Worth It?
Ultimately, my experience with the 400EX big bore kit has been overwhelmingly positive. The added power and performance made my rides more enjoyable, and I felt more confident tackling tougher terrains. If you’re considering a big bore kit for your 400EX, I say go for it! Just make sure to do your research, choose quality components, and be prepared for the extra maintenance that comes with increased performance. Happy riding!
Author Profile
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Hey, I’m Timothy Bush. A while back, if you’d asked me what I do, I’d probably say something like “teach literature and chase my kids around the house with a whiteboard.” But life has a funny way of reshaping your identity. Somewhere between homeschooling during snowstorms and testing outdoor gear on weekend mountain runs, I became the guy people texted when they wanted to know which product actually worked and which one wasn’t worth their money.
Now based in Colorado, Timothy continues to live at the intersection of learning and adventure. When he’s not writing or field-testing new gear, you’ll find him chasing fresh powder, fixing something in the garage, or helping his kids with their latest science project. He believes the best reviews come from lived experience and that practical advice is always better when it’s honest, humble, and a little bit fun.
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