honda 400ex atv performance

The Honda 400EX is a classic sport ATV that can reach a top speed of around 65 mph, thanks to its efficient 397cc engine. With 28 horsepower and solid torque, it offers impressive performance for both casual riders and more adventurous enthusiasts. You'll appreciate the comfortable seating and advanced suspension, making those long rides enjoyable. While it may not be the fastest option available, its reliability and handling on tight trails are unmatched for its class. If you're curious about how to maximize your 400EX's performance, there's plenty more to uncover about performance upgrades and enhancements.

Key Takeaways

  • The Honda 400EX has a stock top speed of around 65 mph, with modifications potentially reaching nearly 70 mph.
  • Its 397cc engine produces 28 horsepower, providing strong bottom and midrange power for recreational riding.
  • Enhancements like upgraded exhaust systems and high-flow air filters can improve throttle response and overall performance.
  • The ATV excels in handling tight trails, making it ideal for casual rides rather than high-speed racing.
  • Resale values vary, with the 2003 model estimated at $3,500, reflecting its reliability and performance in the sport ATV market.

Engine Type: Air-Cooled Single

air cooled single engine type

The Honda 400EX features a robust RFVC air-cooled single-cylinder engine that delivers impressive performance. With a displacement of 397cc, this four-stroke engine generates 28 horsepower at 7000 rpm, making it an exciting choice for sport ATV enthusiasts like you.

The engine's bore and stroke measure 85mm by 70mm, and it boasts a compression ratio of 11:1, ensuring you get the power you crave. Equipped with a 38mm piston-valve carburetor and an accelerator pump, the fuel system enhances throttle response, giving you a more exhilarating ride.

You'll appreciate the electric starter and the reliable CD ignition with electronic advance, which ensures smooth starts every time. Thanks to its air-cooled design, the engine maintains optimal operating temperatures without the added complexity of liquid cooling. The Honda 400EX is known for its durability and has a lightweight structure that enhances acceleration and reduces engine stress.

The Honda 400EX features a 5-speed transmission with reverse, allowing you to navigate various terrains with ease. Its manual, cable-operated wet multiplate clutch contributes to a responsive feel.

With a peak torque output of 63.9 Nm at 6000 rpm, this engine type not only performs well but also provides the durability needed for your adventurous spirit.

Maximizing Engine Efficiency

optimizing engine performance metrics

To maximize your Honda 400EX's engine efficiency, focus on improving throttle response and maintaining proper tire pressure and condition. You'll find that a well-tuned engine can help you reach that impressive top speed of 62 mph. Additionally, ensuring you use the recommended 10w40 ATV oil is crucial for maintaining optimal performance.

Maximum Speed of 62 Mph

Achieving a maximum speed of 62 MPH on the Honda 400EX hinges on maximizing engine efficiency. This impressive speed is attainable thanks to the bike's RFVC air-cooled dry-sump single-cylinder four-stroke engine, which boasts a 397cc displacement and 28 horsepower.

The engine's 11:1 compression ratio and 38mm piston-valve fuel system with an accelerator pump help ensure that you get the most power possible from each drop of fuel. The dry-sump design of the engine also contributes to better oil circulation and cooling, further enhancing performance.

The 5-speed manual transmission, designed specifically for sport use, allows you to optimize your gear shifts based on the terrain and conditions. This adaptability is crucial, as the gear ratios can significantly impact your top speed.

Additionally, the heavy-duty clutch and O-ring-sealed chain contribute to smooth power delivery, reducing energy loss.

To push your 400EX to its limits, consider making minor modifications, such as installing aftermarket pipes or open airboxes. These changes can enhance airflow, further boosting efficiency and potentially raising your top speed into the mid to high 60s.

Throttle Response Improvement

Improving throttle response on your Honda 400EX can significantly enhance your riding experience and overall performance. One effective way to achieve this is by upgrading your exhaust system. Installing a slip-on or full exhaust system not only boosts throttle response but also increases power throughout the engine range. Just remember to adjust your jetting to maintain the correct air-fuel mixture; otherwise, you might risk running lean, which can damage the engine. Additionally, proper exhaust system setup is critical for maximizing engine output.

Another excellent method is enhancing your air intake. Removing the air box lid and adding a high-flow air filter, like one from K&N, can significantly improve airflow and throttle response. Again, jetting adjustments are necessary to ensure your air-fuel mixture remains balanced.

If you're looking for a more advanced option, consider upgrading to a fuel injection (EFI) system. EFI improves throttle response and simplifies tuning for different riding conditions, reducing the need for frequent jetting adjustments.

Finally, engine internal modifications, such as big bore kits and camshaft upgrades, can further enhance power and efficiency, but these also require careful jetting and spark plug adjustments to maximize your results.

Tire Pressure and Condition

Maintaining proper tire pressure is crucial for maximizing the engine efficiency of your Honda 400EX. For optimal performance, aim for a tire pressure between 5-6 psi for general use, but remember that conditions can vary. Always check your tire pressure when the tires are cold, ideally before you hit the trails.

Temperature plays a significant role in tire pressure; for every 10-degree drop, you'll lose about 1 psi. During colder months, ensure your tires aren't under-inflated, as this can lead to uneven wear and reduced traction. Additionally, under-inflated tires may lead to poor handling and compromised safety.

Conversely, in hotter weather, be mindful that air expansion can raise your pressure above recommended levels.

Adjust your tire pressure based on the terrain; lower pressure (around 2.5 psi) works wonders in soft sand, enhancing traction. For hard-packed surfaces, stick to higher pressure for better stability.

Balanced tire pressure improves handling and ride comfort, while also prolonging tire life.

Finally, keep an eye on tire condition—worn or damaged tires can negate all your hard work in maintaining proper pressure. By staying vigilant, you'll enjoy a smoother ride and maximize your Honda 400EX's efficiency.

Comfortable Seating for Long Rides

long ride comfort seating

When you're gearing up for a long ride on the Honda 400EX, the comfortable seating plays a crucial role in your overall experience. The long, narrow seat is designed with superb sport riding ergonomics, which means you can stay comfortable even during extended trips. Its shape allows for easy movement, enhancing your control of the ATV and improving your riding position and stability.

The padding and seat material contribute to your comfort, while features like dogleg levers and an adjustable clutch lever reduce strain on your hands. You'll also appreciate the multi-function handlebar switch, which simplifies operation and minimizes rider fatigue. The rear mudguard paired with rigid footrests provides additional support, making longer rides more enjoyable. Additionally, the Honda 400EX's high-torque, four-stroke engine typically outlasts competitors in the 450cc class when well-maintained.

With independent double-wishbone front suspension offering 8.2 inches of travel and a Pro-Link® rear suspension with 9.1 inches of travel, the ride quality is top-notch. Plus, adjustable suspension settings let you tailor the ride to your preferences, ensuring maximum comfort.

All these features work together, allowing you to focus on the thrill of the ride while keeping fatigue at bay.

Owner Insights: Real-World Experiences

owner experiences and insights

Many Honda 400EX owners rave about their experiences, highlighting the ATV's impressive balance of speed and control. With a stock top speed of around 65 mph, you might find that minor modifications can push that to nearly 70 mph, especially if you optimize conditions. The 25.4 horsepower engine offers a wider powerband compared to two-stroke models, making it easier for you to handle on various terrains. Additionally, the 400EX is considered the best tight trail quad alongside the 300EX, which enhances its appeal for riders who frequent narrow paths.

Reliability is another aspect that owners appreciate. As long as you perform basic maintenance, the 400EX tends to hold up well. Be mindful of common issues, like the wiring harness behind the headlights and rear axle carrier bearings, which may need attention over time.

For those tackling tight trails, the 400EX shines, with advanced suspension improving handling. However, it's not the best choice for open trails where other models might excel.

If you're looking to enhance performance, consider simple upgrades like a vented airbox or an aftermarket exhaust. Many owners have seen significant improvements with these modifications.

Market Positioning Among Rivals

competitive landscape analysis

In the competitive ATV market, the Honda 400EX holds its ground against rivals like the Kawasaki Z400 and KFX400, which are often viewed as faster and more performance-oriented options.

While the Z400 and KFX400 feature water-cooled engines and a lighter frame that enhances their power-to-weight ratio, the 400EX remains a solid choice for those prioritizing reliability. This reliability is further emphasized by the fact that Honda engines are known for longevity and reliability.

Many riders appreciate the durability of the 400EX, especially when considering some frame cracking issues reported in earlier KFX and Z400 models.

Compared to the Yamaha Raptor 350, the 400EX offers superior performance and handling without the higher price tag, making it a better value overall.

In amateur XC racing scenarios, the 400EX can hold its own with the right setup, though it generally trails behind high-performance models like the Honda TRX450R.

It's worth noting that while the 400EX mightn't win races, its reliability and handling make it ideal for tight trails and casual rides.

Ultimately, if you're seeking dependable performance without the frills, the Honda 400EX stands strong against its competitors.

Performance Exhaust System Upgrade

enhanced vehicle exhaust performance

Upgrading the exhaust system on your Honda 400EX can significantly enhance its performance and overall riding experience. By reducing back pressure and improving airflow, you'll enjoy increased horsepower and torque, which translates to better acceleration and potentially higher top speeds in the mid to high 60s mph. Additionally, installing an HMF exhaust system is essential because fuel tuning is mandatory to prevent engine damage.

Full system upgrades, especially when paired with a K&N air filter, can provide noticeable gains in low to midrange power, giving you that extra boost when you need it. Not only does a performance exhaust improve power, but it also enhances safety by directing harmful fumes away from the engine and cabin. With high-quality materials, these systems ensure a longer lifespan and protect other components by optimizing airflow.

Plus, you can customize your ATV's look and sound, choosing from various styles and tones that reflect your personal preference. Installation is generally straightforward, especially with professional help, and you might find that upgraded systems require less maintenance due to their durable materials.

Cost and Dealer Options

pricing and dealership choices

When considering the cost of a Honda 400EX, you'll find a range of prices based on the model year and condition. For instance, a 2008 TRX400EX typically goes for around $3,699, while a 2005 or 2007 model can be found for about $3,499.

If you're looking at older models, like the 2002, expect to pay around $4,495, and for a 2000 model, prices can reach up to $5,699. Current market value for a 2003 Honda 400EX is estimated at around $3,500, which is reflective of the fluctuating demand for older models in today's market.

You'll also come across various dealer options across the U.S., including California, Massachusetts, and Alabama. Dealers like Cal Coast Motorsports and Northstate Powersports often list both standard and modified models, so you have plenty to choose from.

Some dealers even offer additional services, like engine rebuilds at locations such as Brenny's Motorcycle Clinic.

Keep in mind that original purchase prices for models like the 2003 model were around $5,500, but discounts brought it down to about $4,199 to $4,299.

The resale value can vary significantly based on condition, mileage, and any modifications made, which can also influence the pricing you'll encounter.

Recreational Off-Road Enthusiast

adventure in rugged terrains

For recreational off-road enthusiasts, the Honda 400EX stands out as a capable and thrilling ATV. With its 397cc, air-cooled, four-stroke engine producing 28 horsepower, you'll enjoy exhilarating rides over various terrains. Its top speed reaches approximately 72 MPH on pavement, and with some modifications, you can push that to 73 MPH. Even on gravel, you might see speeds of around 71 MPH with upgraded components. The independent double-wishbone suspension provides 8.2 inches of travel in the front and 9.1 inches in the rear, ensuring a smooth ride over bumps and rough trails. The lightweight, sturdy steel frame and a manageable weight of 375 lbs allow for easy handling, whether you're navigating tight turns or open fields. Additionally, many riders have reported that with aftermarket modifications, the speed and performance of the 400EX can be significantly enhanced. With a five-speed transmission and electric start, the Honda 400EX makes it easy to hit the trails quickly. Plus, the dual hydraulic disc brakes deliver reliable stopping power when you need it most.

Whether you're racing friends or exploring new paths, the 400EX offers the perfect blend of performance and reliability for any off-road adventure.

Frequent Electrical System Failures

recurring electrical system issues

While the Honda 400EX offers thrilling performance for off-road adventures, frequent electrical system failures can sour your experience. One of the most common culprits is an overloaded electrical system. If you install high-wattage accessories without upgrading the system, you risk overheating and damaging components.

Loose or corroded connections in the wiring harness can also lead to issues, particularly behind the headlights where wear is common. You might notice symptoms like the engine not starting despite power being present, or flickering lights that leave you stranded. A burnt smell or visible smoke when starting the engine often indicates serious problems, especially with the CDI box or wiring.

It's crucial to be aware that the engine smoking can signify deeper electrical issues that need immediate attention. Checking the main fuse and ensuring tight connections can help, but the underlying issues might be deeper.

Don't overlook battery and charging problems either. A dead battery or corroded terminals can prevent your ATV from firing up.

Regularly inspect the regulator/rectifier and connections for damage, and use a battery tender when storing your 400EX. By staying proactive, you can minimize these electrical headaches and get back to enjoying your rides.

Durable Frame Construction Integrity

sturdy structural design quality

The Honda 400EX's frame construction stands out due to its impressive durability and lightweight design. Made from round-tube steel, this frame strikes the perfect balance between strength and weight, allowing you to navigate challenging terrains with ease. The removable subframe simplifies maintenance, so you can spend more time riding and less time working on your ATV. Designed to withstand the demands of sport riding, the frame ensures you can tackle harsh environments without worry. The aluminum components further enhance the overall performance by reducing the vehicle's weight, allowing for quicker handling and improved agility. Additionally, the 400EX frame costs around $600 due to its mass production, making it an accessible choice for many riders. The independent double-wishbone front suspension offers 8.2 inches of travel, while the Pro-Link rear suspension boasts a fully adjustable large-diameter aluminum-body piggyback Showa shock absorber for 9.1 inches of travel. This combination delivers superb ride quality and stability over rough terrain. With tough steel skid plates protecting vital components, you can ride confidently, knowing your ATV is shielded from potential damage. The Honda 400EX's durable frame construction integrity not only enhances your riding experience but also extends the life of your machine.

Reliable for Recreational Use

dependable for leisure activities

When you hit the trails on a Honda 400EX, you'll quickly appreciate its reliability for recreational use. This ATV excels in various terrains, handling tight trails and technical landscapes with ease.

Whether you're cruising on fire roads or tackling long rides, the 400EX delivers consistent performance throughout. It manages different elevations without significant issues, thanks to its durable suspension and handling that reduce wear and tear over time. Additionally, its renowned durability and reliability means you can trust it for long-term use.

With an air-cooled engine, the risk of radiator damage is minimized, making it a great choice for off-road adventures. Basic maintenance is all it takes to keep this machine running smoothly, though older models might've head gasket concerns.

You can enhance its performance with upgrades like big bore kits and camshafts without compromising reliability. Users consistently report high satisfaction levels, noting the 400EX's capability to handle moderate to heavy use over the years.

While it may not top the speed charts, its strong bottom and midrange power provide a solid experience for recreational riders. Minor issues can be resolved affordably, ensuring that your Honda 400EX remains a dependable companion on every ride.

Frequently Asked Questions

What Is the Honda 400ex's Average Top Speed?

The average top speed of the Honda 400EX typically ranges between 65 to 68 MPH in stock form.

If you're riding in ideal conditions, you might even coax it up to around 72 MPH.

However, various terrains can push that number into the mid to high 60s.

Keep in mind that performance can vary based on any modifications you've made and the overall conditions you're riding in.

Enjoy the ride!

How Does the 400EX Compare to Newer ATVS?

When you compare the 400EX to newer ATVs, you'll find it's still competitive in many aspects.

Its 28 HP engine delivers solid performance, while the long-travel suspension and triple disc brakes ensure great handling and stopping power.

Plus, with a lightweight frame and easy customization options, it remains a popular choice for enthusiasts.

While newer models might've advanced features, the 400EX still holds its own in the sport ATV category.

What Is the Weight of the Honda 400EX?

The Honda 400EX weighs 375 pounds, making it a manageable option for a variety of riders.

When you hop on, you'll appreciate its balance and stability, which are vital for navigating different terrains.

This weight allows you to easily maneuver while still providing a solid feel on the ground.

Whether you're racing or just enjoying a ride, the 400EX's weight contributes to an enjoyable experience overall.

Are There Any Common Modifications for the 400EX?

If you're looking to enhance your Honda 400EX, common modifications include upgrading the exhaust for extra horsepower, tweaking the airbox, and adding a K&N air filter.

You might also consider jetting changes for optimal performance.

For better handling, install A-arms or Elka shocks.

CDI upgrades can increase your RPMs, while regearing sprockets improves acceleration.

These modifications can significantly boost your ATV's performance and overall riding experience.

What Year Models of the 400EX Are the Best?

When deciding on the best year models of the 400EX, you'll want to consider the 2005 version, as it introduced reverse and improved bodywork.

The 1999 model is also notable for its Baja 1000 victory and initial electric start feature.

While later models like the 2008 facelift offer modern aesthetics, the 2005 and 1999 models stand out for their performance and reliability, making them top choices among enthusiasts.

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