How Fast is A 100cc Dirt Bike | Dirt Bikes Action

100cc is one of the most common and the 2nd most powerful dirt bikes right behind 125cc designed for novice, beginners yet passionate dirt bike riders. This is a great dirt bike size meant for newcomers and young riders looking to enhance their skills on a light, easy and speedy machine. However, it might not seem like a big machine because it is not meant for that even. If you are wondering How fast a 100cc dirt bike actually is, this is not alone!

A 100cc dirt bike is supposed to provide a speed of 40 to 60 MPH which translates into 65 to 80 km per hour. However, this thing can vary a lot from model to model and make to make. What makes the difference in actuality is the engine it comes with, the way you ride and the effort you put into its maintenance. This all combines and you get improved speed. There are a lot of things that you should look into in order to get the best of your dirt bike in terms of speed.

How Fast is A 100cc Dirt Bike | What Makes it Faster?

Technically, there are several things that boost or decrease the speed of your dirt bike. Generally, it’s a common thing in 100cc dirt bikes to have a speed of a minimum of 40 mph due to the room of this engine. The fastest or considerably high end 100cc dirt bike may hit the speed of 65 MPH even. That is around 100 km per hour and it is a massive thing for a 100cc engine capacity but in limited bikes!

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Normally, it would be around 55 MPH for max in other bikes but this one is still 90km per hour speed. So, what things affect the speed of your dirt bikes are the ones that we have listed here. Let’s take a detailed look at them one by one.

  • Rider Age and Height

Well, this is a thing you should prioritize before making any choice. A 100cc dirt bike is supposed to be a lightweight thing though, but it can be used both by kids and adults depending upon the seat height ratio of a dirt bike. Now, a 100cc engine doesn’t necessarily fit in mini dirt bikes only, it would be in a big body too, like an 18 inch dirt bike.  If you are an adult and you get a mini dirt bike, it’s not going to be a good and fast thing because it was not meant for adults but for kids.

There is no standard for how old a rider should be to ride that 100cc dirt bike. However, if you are looking to get 100cc for your kids, you should get a mini dirt bike as it would be enough for kids under 11 years, in terms of size and mobility.

If your boy or girl is around 4.5 feet tall, you should get a bike with a seat height between 24 to 26 inches or a maximum of 28 inches. It is an ideal size for kids looking to ride dirt bikes. Similarly, if you are an adult looking to get a 100cc dirt bike for yourself, you can opt for dirt bikes with 29 to 38 inches seat height, ideally enough for people with a height range of 5 to 5.5 feet.

  • Machine Weight and Limit

Well, this is a very basic thing that you should take seriously in your considerations if you want to see your dirt bike move faster to its limit. Dirt bike technically is a machine and every machine has its weight due to metal, accessories and a lot of different things that are used to construct it. All these things always have some density that moves the weighted needle upwards.

If your bike is heavy in weight, it is likely not to move much faster than a lightweight bike will. For example, dirt bikes with 4 stroke engines are bulky in weight due to engine design, hence they are slower. 2 stroke dirt bike engines, however, do not weigh too much and feature a potentially faster speed than a 4 stroke bike.

Generally, a 100cc dirt bike can weigh around 150 pounds to 190 or 200 pounds even. This is the lowest and highest limit you will get on these machines. Most 100cc dirt bikes are capable of handling around 100 to 130 pounds of weight. So, make sure it fits your limit. Otherwise, upgrade to 150, 250 or even 450cc.

  • Engine Displacement and Stroke

The size of an engine is measured by a term called CC which means per cubic centimeter or displacement of that engine. Technically, what it shows is the total amount of fuel the engine could pass through the gas cylinder along with the mixture of air to help in combustion. 100cc means the engine can give 100 cubic cm of gas with its cylinder air during a cycle in full output. Power, in simple!

So, a 100cc engine is more powerful than 40, 50, 60, 75, 80 and 85cc engines as it is capable of producing more horsepower than those low CC engines. A nice 100cc dirt bike is capable of producing around 20 to 35 or 50 HP even. This again depends on several things that increase or decrease its horsepower. The Minimum you will get is 6 HP, but the highest could exceed 40 HP even.

The engine stroke also plays a key role in that. A 100cc dirt bike with 4 stroke engine would generate less horsepower than a 2 stroke engine of similar size. This is due to the mechanism of a 2 stroke engine as it takes 2 fewer strokes to complete the combustion cycle allowing it to generate more power meanwhile than a 4 stroke. The 2 stroke engine not only powers well, but it also moves faster than that.

Also, two stroke engines completed the crank movement faster, but it could not provide a stable riding experience due to the bumpy ride. They are lightweight, however, and this is the reason why mini dirt bikes for kids have 2 stroke engines. In a nutshell, a two stroke 100cc dirt bike is faster than a 4 stroke 100cc dirt bike.

  • Engine Power and Rider Experience

What people do; is try to get the most powerful bike in that league aiming to get the best out of it. Agree and there is no problem with that. In fact, it’s a very good thing that I personally do. However, you need to have good control or make sure you are skillful enough to handle this machine nicely.

You need to have courage, confidence and handy skills on your bike so you can stand out. With all these sets, you are good to go. Just enjoy a good and fast ride in order to experience the best of both worlds with your fast 100cc dirt bike. Also, don’t forget to wear all the protective gear before you sit on your bike. Your dirt bike gear would include a helmet, grip, chest protector, boots, gloves and a jacket.

  • Terrain and Lump sum Speed

Where and how you ride, this factor also improves or slows your dirt bike speed. If you are looking to achieve and maintain the top speed whether it’s a Kawasaki KX 100, XR 100 of Honda or CRF 100, it’s only possible if you are on a slightly stable track with little bumps or obstacles in its way. We’re not talking about smooth or carpeted roads, anything could be stable even if it is an off-road track.

Along with obstacles, if the type of terrain is something else the bike speed could be different too. Like, if there are no obstacles but you are on a muddy road with mud and gravel, you still can’t hit the top speed because your bike could not ride stable and balanced. Otherwise, the tires might get damaged easily.

Some people think riding your dirt bike on asphalt is fun or adventurous or you can hit the top speed multiple times. But, this theory is not completely correct. Remember, a dirt bike is a motocross or an off road machine which is supposed to be off road for the maximum output. You can’t achieve top speed on a dirt bike due to dirt bike tires as they don’t establish a stable grip out there on asphalts.

  • Engine Health and Maintenance

Now, if you have a 100cc dirt bike but you don’t change its oil, its air filter is not clean anymore, and it’s been several months since you added new and fresh engine oil. If that is the case, you can’t get the full efficiency out of the engine or the top speed. In fact, it would only increase the stress on its engine, sadly!

So, the key to top speed is to maintain your dirt bike properly. Maintain your dirt bike by adding Amsoil oil to its engine. Get your bike tuned on proper time and after a specific set of kilometers. Change its oil filter, lubricate the chain and clean it as well. Just check out these things and you will get the max speed.

  • Fuel, Exhaust, Tire and Pressure

If you have a family car, you know the importance of putting the right kind of fuel into it. With the dirt bike as well, you should do the same. I mean, you should pick the nicest fuel out there, i.e, the high octane of 87 grade at least. 82 would be good too but I recommend going upward if you can find and afford it. Octane 95 is a great choice if you prefer economy over performance and adventure.

This fuel is what makes everything different, especially if you are looking to get the top speed out of it. You should never be amazed when it comes to a 2 stroke engine as you would need to mix oil in the fuel to get the best efficiency out of it. 

Along with fuel, you can let your bike push beyond its limit with the help of using nice and proper exhaust. Upgrading your bike’s exhaust can make a slight difference in terms of improving your speed. Along with a new air filter, your new exhaust helps improve the airflow creating room for the engine to fire better.

Another thing you can add is a nice pair of dirt bike tires. If it’s been several months since you have traveled at least 4000 kilometers without changing tires, you should do it now. Adding new tires will not only improve the speed, but it will also improve the grip on your routes generating balance and improving traction.

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Now, if you have mild tires or if they are still usable, you should try adjusting its tire pressure to anything between 8 to 16 or 20 PSI even, depending on the tracks you usually ride at. Because having the right tire pressure can do wonders in terms of rideability, performance, traction as well as in speed.

Who makes the Fastest 100cc dirt bikes?

Currently, there are a few limited brands making 100cc models. In the last decade, a few more options were available compared to today. The reason is, the manufacturers have discontinued those 100cc models and shifted them up to 125 and 150cc machines. 100cc however, is still a requirement and there’s a market as well. So, new entrants have captured that but a few could see success.

Personally, the first 100cc choice is the Kawasaki KX 100 which would come to mind no matter what. It is the fastest 100cc produced by Kawaski while the second one belongs to honda and we will get to it in a while. With the KX 100, you are supposed to hit up to 65 miles per hour speed in certain riding conditions, making it the fastest 100cc dirt bike currently on the market.

Although Honda is a reputable player in this market, they could not even break Kawasaki’s 65 miles per hour record. However, they managed to get somewhere around it or better to say right there where KX100 tops. But, in my view, 65 MPH on Kawasaki’s model is doable while Honda’s discounted CRF 100 may take effort.

However, Honda is in the lead due to their XR 100 making their debut in the league and making Honda the only player with two top class 100cc dirt bike models. Both these 100cc Honda dirt bikes feature 4 stroke 2 cylinders air cooled engines while Kawasaki’s is 2 stroke hence making it technically faster than both. The Kawasaki is a liquid cooled engine, the one of its kind in this 100cc league.

KTM, Yamaha and Husqvarns also make a few 100cc dirt bike models!

100cc Dirt Bike Frequently Asked Questions

  • What is the top speed of a 100cc dirt bike?

The top class and high end 100cc dirt bikes are capable of hitting 65 miles per hour as their top speed while you can maintain a speed of around 40 miles per hour on average. The highest you can touch is around 100 km per hour while 60 to 65 km per hour is the average speed with 100cc dirt bikes.

  • How fast is a 100cc 2 stroke dirt bike than a 4 stroke?

A two stroke dirt is much faster than a four stroke version of the same engine displacement. Generally, a 2 stroke engine is at least 20% faster than 4 strokes. For example, if you are supposed to get 40 miles per hour speed with a 4 stroke 100cc dirt bike, you may get around 50 MPH with its 2 stroke version. Because 2 stroke is lightweight and uses only 2 cranks movement, it is always faster than a 4 stroke.

  • How much does a 100cc dirt bike cost?

This also depends on many things, like which brand you opt for, what are the features and a few other things. A new dirt bike, however, is going to cost you at least $1500 or could go up to $8000. Kawasaki KX 100 for instance, would cost you anything between $4250 to $5000. So, it depends from brand to brand.

  • What age is a 100cc dirt bike for?

A 100cc dirt bike is slightly powerful and a little bit bulky too. It is generally good for at least 10 years old kids while the older the better. Make sure you guide your kids well in terms of safety and control before handing over a bike to them. Do keep an eye out and ensure they are traveling under your supervision. Try getting a speed limiter or throttle reduction kit to stop them from going on faster.

  • How fast is a Honda 100cc dirt bike?

Honda makes two great 100cc dirt bikes for this league. One is their flagship CRF 100 and it is supposed to provide a top speed of 65 miles per hour or 100 km/h. This is achievable in a technically set bike and in certain riding conditions. This one is now discontinued by Honda, however. You can enjoy Honda’s XR100 if you prefer older models with the top speed being stopped at 50 miles per hour.

  • Is a 100cc Dirt Bike Good for Off-Roading?

Yeah, a 100cc is definitely a good off road dirt bike aiming to provide the best suspension powered by a 2 stroke engine capable of producing 6 to 10HP.


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