Honda 400EX Top Speed – Everything You Need to Know

The Honda 400EX is a high-performance machine that has gathered fame in the ATV world. Many off-road enthusiasts praises its engine performance, haulage power, and a wide range features. However, the speed performance of the machine is one aspect that is often downplayed.

In this article, I will discuss all there is to know about the top speed of the 400EX and simple tips that can help you get the best out of the utility machine.

How Fast Does a Honda 400EX Go?

According to the manufacturer, the Honda 400EX can deliver between 65 to 72 miles per hour. However, the average top speed reported by most riders is 68 mph. That said, several factors can impact the speed of the 400EX including the riding conditions, year of manufacture, and modifications made to the vehicle.

How Many Miles Can I Get Out of Honda 400EX?

There is no one-size-fits-all answer to this question. But, like any other vehicle, the lifespan and mileage you will get from your Honda 400EX depends on many factors. These include how well you maintain the vehicle, the type of riding you put it through, and how frequently you use it.

With proper maintenance and regular servicing, you can get over 10,000 miles or 16,093 kilometers from the ATV. That said, here are a few ways you can get the best performance from your Honda 400EX:

Honda 400EX Top Speed

Avoid Difficult Trails

It is a no brainer that many people go for an ATV because they love adventures. But, as the popular saying goes, too much of everything is bad.

In this case, frequent riding and the constant aggressive use of your ATV can lead to unwanted wear and tear. As such, it is always a good idea to use your ATV on light terrains as much as possible to preserve its life.

Use High-Quality Fuel

Ideally, low-quality fuel can affect your Honda 400EX’s performance. As such, avoid using contaminated or old fuel in your machine to keep it going for a long time. In addition, ensure you stick to the best fuel quality.

Proper Tire Care

Another area where you should pay special attention is the tires of your Honda 400EX. A well-maintained tires allows you to get better traction when riding on different terrains. Ensure to conduct routine tire inspections for visible signs of wear and tear, before they lead to more problems.

Watch Your Gear Selection

Now, the gearbox is another area to pay close attention to. Ensure that you select the right gear for your specific riding condition.

Stay on low gears when riding on steep roads. With lower gears, you can get better torque, which will help you climb steep terrains better.

As for flat surfaces, any high gear will be fine. Generally, higher gears provide smooth acceleration and better speed on flat terrains.

To get the best speed out of your Honda 400EX, you will need to mind what gear you use and where.

Routine Maintenance

One of the easiest way to get more mileage from you ATV is by performing a routine maintenance. Ensure to Inspect and replace your air filters when necessary, check for tire pressure, and regularly change the engine oil.

How Much Power Does A Honda 400EX Have?

The Honda 400EX comes with an impressive 397cc four-stroke engine. This engine generates an average of 34 horsepower at its top performance.

With this power output, you are guaranteed ample torque and acceleration, allowing you to ride long distances and navigate rough terrains if you like. This contributes to its agility and top performance, making it popular among ATV enthusiasts.

How to Improve the Honda 400EX Top Speed

Even though the factory standard top speed for 400EX is 72 mph, some riders may still yearn for more speed. If you belong to this category, I have put together a few tips to help with your Honda 400EX speed upgrade:

Upgrade Your Performance Exhaust System

Upgrading the regular exhaust system to a high-performance option can make all the difference with your ATV. Using a free-flowing exhaust, allows your engine to breathe better, which adds more horsepower and torque to your machine. These, in return, improve the overall speed and power of your 400EX engine.

Modify the Air Intake System

The standard air intake system is made up of an air filter and air box. These components allow clean air to enter the engine which control how much fuel the engine receives. In the end, this affects the average speed and power your Honda 400EX produces.

Switching this stock air filter with a high-flow air intake filter means more air can enter the engine. The more air goes in and out of your engine, the more speed and power it will reach.

Try Rejetting the Carburetor

Apart from upgrading the exhaust and air intake system, you also need to increase fuel flow. This way, your air-to-fuel ratio can align for better results. The best way to increase fuel flow on your Honda 400EX is to re-jet the carburetor.

Rejetting a carburetor means changing the size of your carburetor jets so that the engine can get the right amount of fuel it needs. For best performance, consider updating your pilot and needle jets. For the main jet, you only need a turning adjustment.

Switch to High-Performance Tires

The wheel tires on your machine are another parts you need to upgrade to enjoy higher speed levels. For best results, you may need to replace the follow-come tires with aftermarket high-performance ones. With high-performance tires, you can get a better grip and traction, ensuring your machine’s stability when running on top speed. In addition, premium tires will give you more control and stability, thus, improving your overall riding experience.

Cut the Weight

The lesser your Honda 400EX weighs, the better it can perform. So, consider switching its heavier components like the suspension and wheels for lighter alternatives to help reduce the ATV’s total weight. With this, you will get a better power-to-weight ratio, faster acceleration, and better speed.

Note: If considering upgrading your Honda 400EX, pay close attention to local laws and regulations, especially regarding speed limits. Also, consider that a speed upgrade can alter your ATV’s regular functioning. So, you will need to get used to the modifications in a controlled environment before putting the ATV on the road.

Finally, get an experienced mechanic or ATV expert to do this installation. That way, you can rest assured that your modifications are done properly for the best performance.


The Honda 400EX specs are nothing short of a game changer. Whether you want an exhilarating high-speed adventure or a simple off-the-road ride – this ATV promises a memorable riding experience. Although the top speed is around 72 mph, you can surpass this limit by upgrading the exhaust and air intake systems, rejetting the carburetor, cutting the weight, and switching to high-performance tires.

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