How Fast is a 125cc Dirt Bike? [Top Speed Explored]

The 125cc dirt bikes are popular machines. This is where raw power meets adrenaline-fueled excitement. For many younger riders, the 125cc dirt bikes are their introduction to 4-stroke bikes. This means less power, torque and responsiveness compared to motocross bikes with 2-stroke engines. Many brands also offer the faster 2-stroke engines though. But, how fast is a 125cc dirt bike?

Man riding his dirt bike with beautiful sky in the background

A 125cc dirt bike will go as fast as 70-80 mph (113-129 km/h). This speed is fast enough for the bikes to maneuver rough terrains. Yet not too fast for the adult beginners who usually start with this bike engine class.

Some 125cc dirt bikes can be used in motocross racing. They are also a popular choice for many riders. They combine the lightweight feature with speed and agility.

What Determines How Fast Can a 125cc Dirt Bike Go?

The 125cc dirt bike moves as fast. But this speed is subject to change. So, what determines exactly how fast can a 125cc dirt bike go? 

Man on motocross riding his dirt bike in the mud

The top speed of a bike can be determined by factors such as the model of the bike, its power, and terrain type. Even variable conditions like the weight and skills of the rider can affect a bike’s top speed.

Speed Determinant of a 125cc Dirt Bike

When it comes to the speed of a 125cc dirt bike, several factors affect how fast a 125cc dirt bike can go. Some of these factors include:

Engine power and torque

The engine is the heart and soul of any dirt bike. The 125cc dirt bike is no exception. Even though two bike brands may be classified as 125cc, their power outputs vary. This power output is what determines how fast a dirt bike can go. 

Invariably, a higher power output translates to a higher speed. Also, the torque produced by an engine can determine how fast it accelerates. A higher torque allows for a quicker burst of speed.

Rider’s riding skills, Rider’s weight, Bike weight

Man jumping off his dirt bike

Believe it or not, your skills as a rider have a significant impact on how fast your 125cc dirt bike can go. It takes good skills for proper bike handling and cornering techniques. When you have a grip on these skills, you can optimize the bike’s performance. 

Yes, as you may have guessed, weight matters too. A heavier rider will have slower acceleration and reduced top speed. They may even find it challenging to pull off some riding techniques. But adjustable suspension systems can help with this. You can also weigh and unweight your dirt bike.

Type of terrain and track

It’s a no-brainer that the type of terrain you ride on can influence your bike’s speed. A smooth, flat-surfaced track allows for top speed to be reached even faster. This is when compared to the speed attained on a rough, uneven track as typical in off-roading. The presence of obstacles, jumps and tight corners impact how fast you can ride.

Average Speed Range of 125cc Dirt Bikes

The 125cc engine dirt bike delivers impressive power. But its speed cannot be expected to rival that of bikes with higher engine class. The average speed for a 125cc dirt bike is 50-60 mph (80-97 km/h). 

This speed covers the range that different brand models of this class have. The 125cc dirt bike top speed is usually around 70-80 mph. How fast does a 125cc dirt bike go in km/h? This speed is around 113-129 km/h. As stated earlier, the top speed you get from a bike can depend on your riding skills. It can also depend on your weight and the kind of terrain you ride on. 

These factors all interact to contribute to the top speed you can grind out of your bike.

Comparison with other Motorcycle Classes

The 125cc dirt bike is a popular engine class for young and adult beginner riders. But it is not the only dirt bike class in the market. But there are a few other classes that can give it a good run. This is in terms of speed and performance. 

These other motorcycle classes include:

85cc Dirt bikes

The 85cc dirt bikes usually come in 2-stroke engines. Their engines are compact and offer riders great control and balance. Some of them have the option of having their smaller wheels swapped for bigger ones. 

While the 85cc dirt bikes do not have the brute force of larger bikes, they pack a bunch.

“the 125cc bikes have increased power and better suspension”

Ricky Johnson maintains

Still, kids aged 9-14 years old can have a thrilling experience riding this bike. 

250cc Dirt Bikes

The 250cc dirt bikes are less popular than their 85cc or 125cc counterparts. This difference in demand is however not a reflection of its top speed. So, how fast is a 250cc dirt bike? While the top speed varies according to the brand model, it’s around the 70-78 mph (113-126 km/h) mark range. Some are as fast as 80-90 mph (129-145 km/h). 

450cc Dirt Bikes 

Man riding his dirt bike in fast speed

450cc dirt bikes are large and powerful. What they add up in weight, they make up for with speed. Thus, it is no surprise the fastest dirt bike in the world is a 450cc dirt bike. These bikes are used in professional racing by professional riders. Its top speed can be as high as 123 mph (198 km/h).

Top 125cc Dirt Bike Contenders

As a well-known class with great utility, many brands produce several models of 225cc bikes. Here are some of the top 125cc dirt bike contenders in the market:

Overview of Some 2023 Models of Motocross and Full-Size MX Bikes

Many models of 125cc dirt bikes cut across different categories. These categories include enduro, motocross, and even cross-country bikes. Some top contender bikes are:

Motocross KTM 125 SX

This bike features a 2-stroke engine that maintains an exceptional power-to-weight ratio. It has race-ready components that can grind to a top speed of 80 mph (130 km/h).

Motocross Yamaha YZ125

When compared to the KTM 125 SX, the Yamaha YZ125 has a better overall performance. Its clutch action is better and thus, less mistake-prone. The suspension systems of both bikes are arguably equal in performance. But this is weight-dependent. Still, the YZ125 has a top speed of 70 mph (112 km/h).

GasGas MC 125

The GasGas is a motocross bike. It has low-end and peak power when compared to most of its competitors. Additionally, it is lightweight and fast. Not too fast for beginners and or too slow to bore fast riders. For many riders, the GasGas MC 125 is a great balance between affordability and performance.

Motocross Husqvarna TC 125

Enough has been said about 125cc dirt bikes. But it would mean little if the Husqvarna TC 125 is not mentioned.

‘‘ It’s fun to ride a 125cc two-stroke for 30 minutes. But after that, it is tough”.

Jason Thomas – GNCC champion cyclist

Yet, he raced a TC 125 in the XC3 Pro-Am class mud race and attests to it that the bike ‘floats’. This bike dazzles in performance and is renowned for its agility.

Isolated image of Husqvarna TC 125 dirt bike in aqua blue background

Honda CRF125F

The Honda CRF 125F is a trail bike. It offers riders the versatile option of trail and track riding. Unlike the other contenders, the CRF125F has a 4-stroke engine. 

How fast is a 125cc 4-stroke dirt bike? Many riders have said the CRF125F  throttle response is CRISP. It’s great for beginners who can keep up with its 55 mph (89 km/h) top speed. This bike is ideal for off-road excursions.

Comparison Table of the Top Dirt Bike Contenders in the 125cc Class

125 SX
Yamaha YZ125GasGas
MC 125
Husqvarna TC 125 Honda
CRF 125F
Engine 125cc,
Power 30.9Hp 33.5 Hp38.25 Hp40 Hp8.85 Hp
Weight 204 Lbs (92.4 Kg)209 Lbs
(95 Kg)
193 Lbs (87.5 Kg)204 Lbs (92.5 Kg)194 Lbs (87.9 Kg)
Dimensions N/A84.1 in x 32.6 in x
51 in
Top Speed 80 mph
(130 km/h)
70 mph
(112 km/h) 
50-60 mph (80-97 km/h)70 mph
(112 km/h)
55 mph
(89 km/h)

Analysis of the Comparison Table

The KTM 125 SX stands out with its higher top speed of 80 mph (130 km/h). Its speed is an answer to how fast is a 125cc 2-stroke dirt bike. 

But in terms of power, how much hp does a 125cc dirt bike have? While the Husqvarna TC 125 has the highest horsepower of 40hp, its top speed is the same as the Yamaha YZ125. The Honda CRF 125F offers a more modest power output suitable for trail riding.

Pros and Cons

KTM 125 SXLightweight chassis 
Long travel suspension 
Swift response throttle
More expensive than competitors
Stiff clutch
Yamaha YZ125Adjustable shock suspension 
Better gear spacing 
Good combustion efficiency
Performance may be too advanced for beginner riders
Difficult cornering capacity
GasGas MC 125Impressive top-end pull
Flexible chromoly steel frame
Not ideal for less experienced riders
Lingers too long at higher rpm before signing off
Husqvarna TC 125Smooth gear shifts
Exceptional performance
Top-notch handling and control
Dealers are not widespread 
Fragile sub-frame
Honda CRF 125FLong travel suspension
Easy maintenance
Smooth stopping power
Less speed than other competitors in the same class
Mid-range performance

Final Thoughts

The KTM 125 SX is the fastest 125cc dirt bike. From our comparison of top contender bikes in the 125cc class, the GasGas MC 125 and Honda CRF 125F are lighter options weight-wise. This elevates them potentially to offer better maneuverability. 

When looking into how fast is a 125cc dirt bike is, riders should consider all factors that impact speed. This is along with their preferences and riding style. 

Related Article: How Fast Does a 150cc Dirt Bike Go?


How fast can a 125cc bike go?

A 125cc dirt bike can go as fast as 70-80 mph (113-129 km/h).

What age is a 125cc Dirt Bike for?

A 125cc dirt bike is suitable for riders aged 12 years and above.

Can a 125cc go 100 mph? 

No, it is not typical for a 125cc dirt bike to reach a speed of 100 mph. Most stock 125cc bikes cannot reach this speed. But such a speed for a 125cc dirt bike has been recorded before. The average speed for a 125cc dirt bike is 50-60 mph (80-97 km/h). Its top speed hovers around 70-80 mph (113-129 km/h).