How fast does a 125cc dirt bike go? If you have this type of bike or are interested in getting one, keep in mind that a 125cc motorcycle has an average speed of around 55 to 60mph. Additionally, 10 to 15 horsepower is a 125cc engine’s HP.
However, there are factors that will influence the dirt bike’s speed. You may also increase its average speed by upgrading your dirt bike or working on your skills.
Continue reading below to know more!
Table of Contents
How Fast is a 125cc Dirt Bike?
Although the average speed of a 125cc dirt bike is only around 55 to 60mph, it can go as fast as approximately 70-80mph. In km, it’s 112.7 to 128.5 per hour. If you are an experienced rider, you can reach the maximum speed in an hour.
However, the speed of different 125cc bikes may vary depending on their model. For instance, a Yamaha 125cc top speed (specifically YZF R125) is around 75mph while a CRF125F’s top speed is about 50-55mph.
You can take a look at the chart below for more examples:
| Dirt Bike | Top Speed |
| Husqvarna TC-125 Bike | 70 mph |
| Kawasaki KLX 12 | 45 mph |
| Yamaha YZ125X | 60 mph |
| KTM 125 SX | 85 mph |
| Suzuki DR-Z125L | 45 mph |
Speed of 2-stroke and 4-stroke 125cc Dirt Bike
Depending on the model you have, 2-stroke 125cc dirt bikes are designed to generally be a bit faster than 4-stroke ones. The max speed of a 2-stroke motorcycle is around 70 mph, while it is only 35 to 55 mph for 4-stroke 12cc motorcycles.
In addition, 2-stroke dirt bikes can reach their top speed faster (i.e., in under 5 seconds) than 4-stroke dirt bikes in general.
Factors That Affect a 125cc Dirt Bike’s Speed
How fast or slow your 125cc dirt bike is will depend on a lot of factors. I listed some examples below.
1. Stroke types: Four-Stroke vs. Two-Stroke
The type of stroke your bike has can impact its performance. For instance, a 125cc 2-stroke dirt bike is often faster than a 125cc 4-stroke dirt bike.
You may watch this video to see how fast a 125cc 2-stroke dirt bike can go.
2. Engine size
Your engine size or cc (cubic centimeters) determines the power and size of your dirt bike’s engine. Thus, different sizes have various maximum speeds. The rule of thumb is that the higher the cc is, the faster your motorcycle is.
A 50cc dirt bike has an average speed of 25-40mph, while a 250cc dirt bike can go as fast as 80mph.
Take a look at the chart below for the average speeds for different engine sizes.
| Engine Size | Average Speed |
| 80cc | 45-55 mph |
| 100cc | 50-80 mph |
| 110cc | 50-55 mph |
| 150cc | 50-60 mph |
| 200cc | 60 mph (approx.) |
| 400cc | 87 mph (approx.) |
| 450cc | 90 mph (approx.) |
3. Tires
If you have lightweight and quality tires, you can reach higher speeds. In contrast, if you have bulky tires, your dirt bike will run much slower because your dirt bike is heavier.
4. Modifications
Modifications are critical to how fast or slow your dirt bike can go. If your 125cc motorcycle is highly modified, it’s more likely to have more speed than regular 125cc bikes.
By upgrading your sprocket, you can increase its speed due to improved torque acceleration.
Another example is replacing your exhaust pipe. Adding a pipe to a 2-stroke dirt bike can allow your dirt bike to increase its speed.
5. Fuel type
Depending on the type of fuel that suits your engine, such as 87-Octane, 90+ Octane, and 85 Octane, your fuel will impact the speed of the bike. For instance, choosing high-quality fuel will make it run much faster.
6. Environment
Environmental factors will affect your dirt bike’s speed. FIY, riding your motorcycle on a wet road with no traction will not allow your bike to pick up much speed.
Thus, it’s important to assess your environment first if you plan to go faster or reach your dirt bike’s maximum speed.
Tips to Increase a 125cc Dirt Bike’s Average Speed
The top speed of a 125cc dirt bike that was ever recorded was around 100mph. If you want to reach the same speed or at least increase how fast you go with the same bike, here are some tips to help you.
1. Become fitter
A rider’s weight can influence the speed of their dirt bike. Thus, to increase the bike speed, it’s recommended to work on your physical fitness.
2. Upgrade exhaust
You can cover much more distance if you replace or upgrade the exhaust of your dirt bike. It will become more lightweight by improving the air circulation of your motorcycle, thus allowing it to go faster.
3. Modify suspension
Aside from allowing you to have a much more comfortable ride on terrains, adjusting your suspension will improve the average speed. The reason is that you can better manage your motorcycle, allowing you to have a smoother and faster ride.
4. Improve skills
Even if your dirt bike has the right modifications to go faster, you cannot increase your speed if you don’t know how to handle your dirt bike.
As such, to improve the average speed of a 125cc motorcycle, it’s best if you practice more to become more comfortable riding your bike. As you become an expert in riding your dirt bike, you can drive it faster while being safe as well.
5. Avoid having a full tank
As having a full tank will make your motorcycle heavier, try to avoid a full-fueled tank to make your dirt bike less heavy. This way, not only will it allow more speed, but it’ll also make your bike more stable.
Things to Consider When Going the Maximum Speed
Driving at high speed feels exhilarating, but your safety should always be a priority.
Thus, always wear complete gear and appropriate clothing to avoid injuries. Also, take into consideration the capacity of your engine and your skills as a rider to avoid any accident or damaging your motorcycle.
In addition, you need to thoroughly check your dirt bike before going on a ride and assess your environment to avoid injuries or even death.
FAQs
What is the cost of a 125cc dirt bike?
This type of bike usually costs around 3,000 to 8,000 dollars. Please check the chart below for examples.
| Model | Approximate Price |
| Honda CRF125 | $3,199 |
| Yamaha TT-R125LE | $3,349 |
| Suzuki DR-Z125L | $3,349 |
| Yamaha YZ125X | $6,699 |
| KTM 125 SX | $7,399 |
Is a 125cc dirt bike good for beginners?
First off, please keep in mind that 55 to 60 miles per hour is 125cc’s average speed. Thus, it can be too big and powerful for a kid who has no prior experience riding a motorcycle.
However, if you’re an adult who’s starting to get into dirt bikes, this bike engine would work for you.
Who should ride a 125cc dirt bike?
These bikes are for people who are between 5 foot 5 to 5 foot 11. Generally, if you’re a kid with prior experience (ideally with experience riding 80cc dirt bikes), it is ideal if you want to upgrade.
In addition, if you’re an adult who wants to learn to ride a dirt bike, a 125cc motorcycle will provide you with great performance and test your skills.
How to convert 125cc to horsepower?
To easily convert 125cc to horsepower, you may check this online calculator. 125cc in HP is approximately 10 to 15 HP.
Conclusion
The answer to your question, “How fast does a 125cc dirt bike go”, is 55 to 60mph. Given your dirt bike’s capacity, the top speed of a 125cc motorcycle can reach around 70-80mph. In addition, you can expect around 10-15 HP for 125cc horsepower.
Lastly, keep in mind that there are factors that affect the average speed of a dirt bike, such as its engine, tires, certain modifications, and fuel. If you’re interested in increasing its average speed, you may work on your physical health, upgrade your exhaust, modify your suspension, and improve your skills as a rider.
Happy riding!
