How Fast Does a 125cc Dirt Bike Go? Read the Ultimate Guide

How Fast Does a 125cc Dirt Bike Go? Read the Ultimate Guide

Suppliers are legally required to include that information with the dirt bike so the customer is aware of the limits and what the safest maximum speed is to travel. So, how fast does a 125cc dirt bike go?

A 125cc dirt bike’s top speed usually ranges between 55 and 60 mph. The majority of riders won’t achieve these top speeds because they haven’t yet mastered the art of dirt riding.

Keep reading.

How Fast Does a 125cc Dirt Bike Go?

A 125cc dirt bike’s top speed usually ranges between 55 and 60 mph. The majority of riders won’t achieve these top speeds because they haven’t yet mastered the art of dirt riding.

With a top speed of 100 mph, at least one other competitor will be competing. On the other hand, the dirt bike is being pushed too far. Compared to its larger competitors, the 125cc engine produces significantly less power. Although it’s slow, you can speed it up with a few performance adjustments and riding techniques.

How Fast Does a 125cc Dirt Bike Go Read the Ultimate Guide
How Fast Does a 125cc Dirt Bike Go? Read the Ultimate Guide

Factors That Determine the Speed of a 125cc Dirt Bike

Have you ever gone to a dirt bike race? If you have, then you’ve probably overheard rumors and claims about which rider or dirt bike was the fastest on a particular 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 sprocket gearing, modifications, and numerous other underlying factors. Here is a thorough explanation of how dirt bikes, especially those with 125cc engines, determine their speed.

The Engine Size

As was already mentioned, there are various engine sizes available for all types of motorcycles. This element is very important in determining the bike’s speed and horsepower.

The standard dirt bikes, it goes without saying, have engines that range in size from 50 cc to 140 cc. The majority of manufacturers go above and beyond by creating additional models with engines ranging in size from 175 cc to 250 cc, but these engine capacities are far above the typical dirt bike motorbike class.

Dirt bikes are made to rev as high as possible in each gear more quickly than other types of bikes, like bit bikes, in order to keep up with them. If it is a 50cc bike, the top speed may be between 15 and 25 miles per hour when riding on short sections using the lower gears. The bike’s top speed, however, is in the neighborhood of 50 miles per hour on longer sections.

You should anticipate a top speed of 70 miles per hour when riding a 125cc dirt bike in high gear with the stock sprocket gearing. Consequently, a major factor in determining how fast your dirt bike will go is the size of the engine.

Sprocket Gearing

You must be aware that the base ratio gear for your dirt bike can be created using the smaller front drive sprocket and larger rear sprocket gearing. The manufacturers are attempting to reach more consumers on the market today by doing this.

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

Typically, the standard sprocket gearing configuration is 14/42. This indicates that the 42-tooth sprocket gearing is located at the back of your bike, while the 14-tooth drive sprocket gear is in the front.

You’ll discover that the typical speed of, say, a 50cc dirt bike ranges from 22 to 25 miles per hour when you use the engine’s red line as your benchmark.

The only reference point for this observation is the first gear’s top speed of 15 miles per hour.

However, if you use the gear, you might reach the top speed of 50 mph. This indicates that your 125cc dirt bike’s average speed will probably be 35 miles per hour when you apply the same red line benchmark to it. A 125cc dirt bike’s sprocket gearing is one of the factors that determines how quickly it can travel, as is clear from the information provided.


When adjusting the speed of your dirt bike, modifications are essential. The only way to view it positively in this context is to increase speed. Everyone wants their dirt bikes to be moving a little bit more quickly than their rivals.

How would you manage 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 stock sprockets on your dirt bike.

To reach the bike’s top speed, for instance, you might completely swap out the stock 14-tooth drive sprocket for a 15-tooth one. Similar to changing your bike’s stock 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 mechanics favor a gain in the bike’s exceptional average speed of no more than 3 miles per hour as a way to increase its speed. Given that dirt bikes are primarily made to handle the toughest terrain that regular bikes cannot handle, that is not a bad idea.

You can decide whether you’ll be in the front group of bikers during a dirt bike expedition by adding 5 miles per hour to your 125cc average speed of 35 miles per hour.

In other words, knowing how the gearing on the sprockets works will help you determine how to increase the average speed of your bike without significantly reducing torque acceleration.

In this regard, the torque acceleration is essential for your bike to quickly reach top speeds. Your dirt bike’s speed can be significantly increased through modifications, which will put you far ahead of other riders.

Time Trials

You can use time trials to determine the dirt bike’s average speed. The purpose of this kind of trial is to assist riders in determining the precise speed at which their dirt bikes can travel.

To get the best results, you must first define a course (over a predetermined distance), then recruit an amateur dirt bike rider, a timekeeper, and an experienced rider.

To obtain the average data, permit each rider to complete a minimum of three laps on 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 calculations based on the size of the engine and the sprocket gearing in your dirt bike.

In the end, you might reach the conclusion that the dirt bike rider’s experience and level of expertise directly correlate with the average speed in miles per hour.

The slower speed of dirt bikes, when compared to the larger bikes, can be easily said to be a deliberate choice on the part of the manufacturers, which is good news for the safety aspect of these bikes.

Simply put, the manufacturer’s specifications for the same model of dirt bikes will determine your safety concerns while riding. These time trials are essential for ensuring that, no matter where you ride your 125cc dirt bike, you are aware of its maximum average speed.

How Fast Does a 125cc Dirt Bike Go Read the Ultimate Guide
How Fast Does a 125cc Dirt Bike Go? Read the Ultimate Guide

How Long Does It Take to Reach Top Speeds?

Since dirt bikes are constantly making turns on the track or traveling on rocky trails, they rarely reach their top speeds. In most cases, acceleration is more crucial than top speed alone, and the time it takes to get there will vary depending on whether you’re riding a 2-stroke or 4-stroke.

2-strokes are much quicker to accelerate compared to 4-strokes and that’s why they’re normally used on the track. A 125cc 2-stroke could easily reach its top speed in under 5 seconds while a 4-stroke would take a little bit longer. Additionally, it will depend on the weight and skill of the bikers.

A complete novice riding a 2-stroke dirt bike will probably be unable to handle the power and end up spinning out (taking much longer to reach top speed). Furthermore, if you weigh significantly more than the other person, it will take you a lot longer to reach your top speed. However, on the whole, the figures I mentioned appear to be the consensus.

The Dangers of Speed

Any rolling object can be hazardous if you lack experience, regardless of what you’re on. For older children (who typically lack much biking experience), a 125cc dirt bike is the best option. You’re just going to have to accept that if you buy your kid a dirt bike, they will fall.

Even a 50cc motorcycle can start moving, so there’s always a chance you’ll crash. Over the years, I’ve fallen a fair amount (on bikes of all sizes), but with each fall, I became aware of my mistakes. Provide your child with safety gear, demonstrate how to operate the bike correctly, and allow them to experience failure before trying again.

125cc Dirt Bike Performance Tips and Tricks

A 125cc bike is simple and frequently designed with beginners in mind, so we don’t expect much from it. However, there are a few things you can do to help it perform better, such as the following:

Work on Your Physical Fitness

To race at top speed on a track, you require more than just a dirt bike. Both mental and physical well-being are significant. Use this strategy to get your body ready for the ride’s demands. You can tell how fit you are by how easily you can accelerate to the top speed on the dirt bike.

One of the many skills you should be able to master is the proper stance. You can achieve the ideal balance while riding in this way. You distribute your weight evenly and improve the bike’s handling as a result.

It’s important to take care of your body. This will help you become stronger both mentally and physically. As a result, you’ll be more equipped to face the difficulties presented by the track and possess the mental clarity necessary to let your inner beast loose while riding a dirt bike.

Disconnect and Replace the Exhaust Pipe

Even if a rider is mentally and physically prepared, they won’t be as quick on a shoddy bike. The exhaust is among the most promising improvements you can make in light of this information.

Without a muffler, the exhaust system would not be complete. It is possible to increase speed gradually by adding a pipe to a two-stroke dirt bike engine or a slip-on to a four-stroke engine. This muffler upgrade is an easy and quick fix that takes no more than 15 minutes to complete.

Adjust the Suspension

A 125cc dirt bike aftermarket suspension may at first glance seem pricey. Once you realize how it can speed up things, you’ll realize it’s worthwhile. Your bike will be more comfortable because it reduces shock.

Even in the most difficult terrains, a vehicle can be driven with greater control thanks to better suspension. The bike’s speed can be increased with better control of the vehicle. It also enhances the balance of the bike as a whole.

Cleanliness is Key!

Even if you don’t have a lot of money to spend on aftermarket modifications, your dirt bike can still become faster. Regular cleaning can help you achieve this. Over time, a bike’s speed may decrease as mud and dirt accumulate on its tires and other parts.

If the dirt bike’s components are not properly maintained, they will deteriorate more quickly. As a result, speed is also negatively impacted. Any parts that are no longer functioning properly should be replaced in addition to cleaning.

Regular lubrication is also required in order to keep your dirt bike clean. Doing this will ensure that everything is operating without a hitch. As a result, the cycle might become slow and unresponsive.

How Fast Does a 125cc Dirt Bike Go Read the Ultimate Guide
How Fast Does a 125cc Dirt Bike Go? Read the Ultimate Guide


How Fast Does a 250cc Dirt Bike Go?

Going fast is fun in large part because of the acceleration. 250cc dirt bikes can achieve top speeds in as little as 4 seconds on average! That’s a ton of power!

How Fast Does a 450cc Dirt Bike Go?

110 mph is the top speed a 450cc dirt bike can travel.

Conclusion: How Fast Does a 125cc Dirt Bike Go?

Market share leadership belongs to the 125cc dirt bike category. It is a smaller bike with less power than the other types. However, a 125cc dirt bike can be a fun ride for beginners with the right gear, such as riding boots and a helmet.

If you have any questions, feel free to post a comment. I am thankful that you read.

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