How Fast Can 125cc Dirt Bikes Go?

You should be aware that dirt motorcycles first gained popularity in the 1960s. Since then, as more riders have taken to the notion of dirt bikes, they have spread more widely. In an effort to outdo possible bike opponents, individual riders began altering their bikes for off-road capabilities.

So how fast can 125cc dirt bikes go? 125cc dirt motorcycles reach 55 to 60 mph. Heavy riders and downhill roads may surpass this range. Dirt bike manufacturers warn riders not to do this on purpose for safety reasons.

Further in this article, I will teach you all in detail about the speed of 125cc dirt bikes, so stay with me if you want to learn more.

How Fast Can 125cc Dirt Bikes Go?

Off-road motorcycling aficionados decided to ride conventional street motorbikes over difficult terrain before off-road bikes began to be mass-produced in the middle of the 20th century.

Riding in off the paved roads presented a lot of challenges because it was the only choice. For instance, most riders would experience a high likelihood of becoming stuck when riding in muddy or sandy terrain.

These issues forced motorcycle makers to come up with a practical fix. And when World War II was at its worst, dirt bikes were all the rage.

Bikers were inspired to take their excursions anywhere, including woods and unpaved places, by their capacity to be driven in nearly any terrain. More light motorcycles were produced as the conflict progressed.

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Nevertheless, the development of dirt motorcycles has always been a slow process. Speed is now the most important feature, but there are still other things that make dirt bikes the preferred option for individuals who want to explore off-road. And this raises the issue of how quickly a 125cc dirt bike can ride.

According to reports, the highest speeds of dirt bikes with 125cc engines range from 55 to 60 mph. Heavy riders and downhill road conditions may enable the operating speed to exceed this range. However, for safety concerns, dirt bike manufacturers do not advise riders to let this happen on purpose.

The majority of dirt motorcycles with 125 cc engines have horsepower ranging from 5.9 to 7.8 at a mind-blowing 7500 revolutions per minute (rpm). The most contemporary kind of engines one can imagine are single-cylinder, 4-stroke ones seen on these bikes.

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Intake, compression, power, and exhaust are the four main stages of these engines, in that order. In the parts that follow, you may read more about what causes these bikes to reach speeds of up to 60 miles per hour.

What Determines a 125cc Dirt Bike’s Speed?

Do you enjoy watching dirt bike races? If so, you must have heard rumors and claims about which rider or dirt bike was the quickest on a certain surface. These motorcycles come in a variety of sizes and power outputs.

The average speed of these bikes varies, though, depending on the size of the engines, the gearing of the sprockets, customizations, and several other underlying elements. Here is a thorough explanation of how dirt bikes, especially ones with 125cc engines, calculate their speed.

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Engine Dimensions

All sorts of motorcycles have varied engine sizes, as was previously explained. This element is highly important in determining the bike’s speed and horsepower.

Naturally, ordinary dirt bikes feature engines that range in size from 50 ccs to 140 ccs. Most companies go above and beyond by creating additional models with 175- to 250-cc engines, however, these engine sizes are far larger than the typical dirt bike motorcycle class.

Dirt bikes are built to achieve the maximum revolutions per minute (rpm) in each gear more quickly than other bike categories, including bit bikes. If it is a 50cc bike, the peak speed may range between 15 and 25 miles per hour when going on short parts utilizing the lowest gears. The bike can reach a peak speed of around 50 miles per hour on longer parts, though.

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When riding a 125cc dirt bike in high gear and using the factory sprocket gearing, you may anticipate reaching a peak speed of 70 mph. Because of this, the size of the engine plays a crucial role in determining how fast your dirt bike will ride.


When it comes to changing your dirt bike’s speed, adjustments are essential. The only positive perspective, in this case, is one of rising speed. Everyone wants their dirt bike to ride somewhat more quickly than their rivals, after all.

How would you do it if you wanted to boost your bike’s average speed without sacrificing its low-end torque acceleration? It’s an easy question to answer. The first thing you’ll do is swap out one of the factory sprockets on your dirt bike.

To reach the bike’s peak speed, for instance, you may completely swap out the conventional 14-tooth drive sprocket for a 15-tooth one. Similar to changing your bike’s factory 42-tooth rear sprocket to a 32-tooth one, doing so will increase speed but have an impact on low-end torque acceleration.

Many 50cc race technicians want an increase in the bike’s top speed to no more than 3 mph in order to increase the bike’s speed. Given that dirt bikes are generally made for the most challenging terrain that regular bikes cannot survive, that is not a terrible concept.

You may decide whether you’ll be in the first group of riders on a dirt bike trip by adding 5 miles per hour to your 125cc average speed of 35 miles per hour.

To put it another way, knowing how the sprocket gearing operates can help you determine how to raise the average speed of your motorcycle without really lowering torque acceleration.

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In this regard, torque acceleration is essential for your bike to reach high speeds in a matter of seconds or minutes. Your dirt bike’s speed may be significantly increased by modifications, giving you a significant advantage over other riders.

Timed Events

You may use time trials to determine the dirt bike’s average speed. This kind of test was created to assist riders in determining the precise speed their dirt motorcycles can go at.

You must first define a route (of a specified length) before enrolling a beginner dirt bike rider, a timekeeper, and an experienced rider in order to achieve the best results.

To get the average statistics, let each rider complete at least three laps of that specific course. After completing this exercise, you will be shocked to learn that the data you have gathered is probably going to match up with the estimates based on the size of the engine and the sprocket gearing on your dirt bike.

You may eventually reach the conclusion that the rider’s experience and level of competence closely correlate with the dirt bike’s average speed in miles per hour.

The slower speed of dirt bikes, in comparison to the bigger bikes, can be readily said to be an intentional choice on the part of the makers, which is good news for the safety element of these motorcycles.

Simply put, your safety concerns when riding a dirt bike rely on the manufacturer’s standards for that particular kind of bike. These time trials are essential for guaranteeing that, no matter where you ride your 125cc dirt bike, you are aware of its maximum average speed.

Sprocket Gearing

You must be aware that the basic ratio gear for your dirt bike may be created using the smaller front drive sprocket and bigger rear sprocket gearing. The producers do this in an effort to reach more customers on the market today.

Simply equipping dirt bikes with a sprocket gearing arrangement capable of giving you the desired performance will yield the base gear ratio.

The typical sprocket gearing configuration is typically 14/42. This indicates that your bike’s 14-tooth driving sprocket gear is positioned in the front while the 42-tooth sprocket gearing is in the back.

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Using the engine rotations per minute red line as a guide, you’ll see that the average speed of a 50cc dirt bike runs from 22 to 25 miles per hour.

This conclusion is primarily based on the first gear’s maximum speed of 15 miles per hour.

However, if you use the gear, you may reach the peak speed of 50 mph. This indicates that your 125cc dirt bike’s average speed is probably going to be 35 miles per hour when you apply the same red line benchmark to it. This information makes it clear that a 125cc dirt bike’s sprocket gearing is one of the factors that determine how quickly it can go.


You can simply determine the speed of your 125cc dirt bike from the conversation. Based on the surface, this sort of bike may reach an average speed of 55 to 60 miles per hour.

If you are riding downhill, the speed may even exceed 60 mph, however, the producers of these bikes advise users against exceeding the average peak speed for security reasons.

You must take into account a few things in order for your dirt bike to go at such speeds. These variables include, among others, the engine size (which in this case is 125cc), sprocket gearing, adjustments, and time trials.


Hello there fellow motorcycle enthusiasts; I’m Mihael. The first motorcycle I had was a scooter Gilera vxr 200 from 2003. This is the motorcycle I fell in love with, which brought me into the moto world. Since then, I have been riding many kinds of bikes, from dirt bikes to race bikes. At the moment, I have a Kawasaki Z750 from 2004, and all I can say is that it is a hell of a bike. I have been riding motorcycles for the last 10 years, and during this period, I have been to many locations where I would probably not be without my bike. My goal is to give you the best advice and tips possible that I have been using myself and that all of my biker friends find helpful to them as well.

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