Dirt bikes, also known as motocross bikes give the rider a sense of freedom and exhilaration when they are driven off-road. These bikes are not usually made for achieving extreme speeds, rather they are designed to handle difficult navigating the terrain with ease. But it doesn’t necessarily imply that dirt bikes, especially 450cc ones, can not achieve high speeds.
But how fast can a 450cc dirt bike go? Although this depends on a few factors such as the engine of the bike, the rider, the bike’s weight, etc, the 450cc bikes in general can be as fast as 87 mph on average. But some bikes can even go to 90 mph.
Let’s take a look at the ins and outs of the max speed of 450cc dirt bikes and also see how they measure up against 500, 600, and 1000cc ones.
Max speed of 450cc dirt bikes: How fast can they go?
Dirt bikes are not meant for being driven on the highway at a breakneck speed for an extended amount of time. So these bikes don’t achieve as much speed as people do. But these bikes aren’t slow either. After all, they ARE meant for extreme sports.
But how fast does a 450cc bike go? The average top speed of a 450cc bike is around 87 mph. But models such as the KTM 450 SX-F can run as fast as 123 miles per hour, which in all honesty, is quite astounding for a dirt bike.
What is the top speed of a 500cc dirt bike?
Like 450cc dirt bikes, 500cc dirt bikes can also go fast depending on a lot of factors. But this speed can’t be maintained for a long time. Also, some bikers feel that 500cc bikes are too fast for dirt tracks, which are full of stones, rocks, bushes, etc. The 500cc bikes’ speed makes it harder to control them in these terrains.
So, how fast does a 500cc dirt bike go? Older models of 500cc bikes had a top speed in the region of 90mph. But newer models can attain a max speed of 120 miles per hour. Such new models are the Kawasaki KX500 and the SWM RS500.
Max speed of 600cc dirt bikes: How much is it?
The 600cc dirt bikes are very powerful machines. These bikes are so powerful, that experts forbid beginners from using them right away. So naturally, rookies ask veterans, how fast does a 600cc dirt bike go?
The answer is, too fast. Models like the YZF-R6 can attain an astounding top speed of 174 miles per hour like it’s nobody’s business. On the other hand, there are models such as the Kawasaki Vulcan S, which can attain a max speed of 112 miles per hour, which isn’t too shabby either. For comparison, the fastest that a 450cc dirt bike can go is 123mph, which is only a few mph more than the Kawasaki Vulcan S. All in all, the average top speed of a 600cc dirt bike is around 130mph.
1000cc dirt bikes: How much is their max speed?
It has been mentioned before that 600cc bikes are a no-go for beginners. So what about the 1000cc ones? Not only are 1000cc bikes forbidden for beginners, but even intermediate bikers are also suggested not to ride 1000cc bikes for their safety.
So how fast does a 1000cc dirt bike go for them to be exclusive to the most experienced of the bikers only? The average top speed of 1000cc bikes is approximately 188 miles per hour. If you think this is fast, you have heard nothing yet.
Almost all 1000cc dirt bikes have rev limiters placed on their engines. These limiters protect the engine from damage. Once these limiters are removed, some bikes such as the Dodge Tomahawk can reach extraordinary speeds of 420mph. No wonder these bikes are not fit for beginners as even experienced pros have a hard time controlling these.
But not all 1000cc bikes can attain the breakneck speed of 400mph odd. The 2018 Harley Commodus can attain a modest top speed of 110mph when its limiter is removed.
What affects the top speed of a dirt bike?
Now that you’ve known about the varying top speeds of bikes with different engines, naturally, it makes you wonder what makes these bikes go so fast. As mentioned before, not all bikes can reach their top speeds due to various reasons. Let’s take a look at these reasons :
1. The stroke of the engine
When it comes to reaching a top speed, a lot depends on the stroke of the engine of the dirt bike. This is quite a dilemma if I’m being totally honest. Because when the engine runs at a high speed, the 4-stroke engines outperform the 2-stroke engines.
But that is supposed to make things crystal clear, right? Well, not quite when it comes to dirt bikes. See, dirt bikes are not primarily built for high-speed racing. Speed is an important factor, yes, but what’s most important is the maneuverability and durability of the bike in harsh conditions. That’s why when it comes to dirt bikes, 2-stroke engines are considered better than 4-stroke ones.
4-stroke engines are heavier than their 2-stroke counterparts. This brings down the overall top speed of the bike. This is why when a, for example, 250cc bike has a 4-stroke engine in it, the fastest it can go is 80 miles per hour. On the other hand, the same bike can go as fast as 85 miles per hour with a 2-stroke engine.
But does the increase in speed make it the undisputed best for a dirt bike? Not necessarily. While the 2-stroke engine gives the rider an edge when speed is concerned, maintaining such a dirt bike is harder than maintaining a 4-stroke dirt bike.
2. The brand of the bike
This will sound a bit petty and presumptuous, but bikes with a higher brand as well as monetary value will always outperform and outrun a bike on the opposite side of the spectrum. Sometimes even a bike of a lower cc can easily outrun a bike of a higher cc just due to being from a much better brand.
Example: KTM 450SX-F has a max speed of 123 miles per hour, which can leave a Honda XR in the dust despite the latter having a 650cc engine. The Honda’s max speed is around 110mph, which is quite less than the max speed of the KTM.
3. Biker’s physicality
A vehicle is as good as the person driving it. The biker’s physical condition also plays a vital role in determining the bike’s top speed. When it comes to riders who have a bit more weight, their bikes tend to underperform when it comes to attaining top speed. This happens because the rider’s weight increases the overall weight of the bike, which makes it harder for it to reach its maximum speed.
Another thing that affects how fast the bikes will run is the height of the biker. If a biker is tall, their height makes wind crash against them more. This happens as tall people have more body area which can resist wind. As a result, the bike slows down.
4. Bike’s weight
This was hinted at in the previous points, as the overall weight of the bike plays a huge role in determining whether it will reach full speed or not. When I was talking about 4-stroke bikes, I said that they are not ideal for dirt bikes because of this very reason.
The heavier a bike is, the harder it is for it to move around. Since it can’t move around freely, it can’t reach the maximum speed. So if a bike has an engine of higher cc, it still can be outrun by a bike with a lower cc because of the weight difference.
5. Condition of the terrain
Another factor that plays a huge role in determining the top speed of a dirt bike is the terrain it has been driven on. Terrains such as wet roads or even ice will help the bike reach its top speed. Because the friction between the surface and the tire is quite low on these surfaces which makes the bike go faster.
On the other hand, mountainsides or tracks off-road are not suitable for attaining max speeds. These terrains have too many things in the way and cause a lot of friction. They also contain many twists and turns which is detrimental to reaching top speed for a dirt bike.
6. The direction of the wind
If the goal is to reach top speed, the direction of the wind is a very important factor. This is applicable in everything where speed is concerned. If the bike is driven along the wind direction, it will reach max speed faster. On the other hand, driving a bike opposite the wind direction will be a hindrance to the bike reaching its top speed.
7. Number of cylinders in the engine
Cylinders burn the fuels and create power for the engine. So it might be seen that the greater the number of cylinders in the engine is, the faster the bike will go. Then again, more cylinders mean that fuel is going to burn faster as well. So, it is not very fuel efficient to use an engine with too many cylinders. The optimum number of cylinders in an engine to attain the top speed of a dirt bike is 4.
How to make a dirt bike reach a top speed
Now that the factors affecting the top speed are known, it’s only fair that a biker should know how to deal with these to make their bike go faster. Here are a few tips that might help the cause:
1. Reducing the weight of the bike
It should be quite clear by now that a lighter bike has more chance of reaching its top speed than a heavier bike. So it is best to shed all the unnecessary weight from a dirt bike for it to go as fast as it can. There are quite a few ways you can do that.
First, you can make sure you aren’t the factor that is keeping the bike from reaching its full potential. If you are on the heavy side, try to lose as much weight as possible.
Next, the various parts of the bike such as nuts and bolts can be replaced with titanium parts. These titanium parts are lighter and more durable than steel-made parts. Although the price will be quite hefty.
Third, if the race isn’t too long, there is no point in having a full tank of gas. Just filling the tank up with the necessary amount of gas will do.
Finally, using 2-stroke engines is a great way of making the bike lighter. As I mentioned before, 4-stroke engines are heavier and so slow the bike down.
2. Changing the gearing
Changing the gearing of a bike means altering its specifications to suit a certain requirement. So making appropriate changes to a dirt bike so that it accelerates faster and reaches top speed earlier than ever before is a good way to go about it.
Examples of such gearing changes are installing a larger rear sprocket or a smaller front sprocket. This helps in getting faster acceleration. For higher top speed, however, the exact opposite arrangements have to be made.
3. Increasing the skill of the rider
A very good dirt bike with all of the best specifications in the world will not be able to attain top speed if the guy riding it isn’t up to the task. A skilled rider can squeeze the last bit of performance out of a bike. So it’s a must that the rider is as good as the bike itself to be able to gain maximum speed.
4. Performing regular maintenance on the dirt bike
Just having a good dirt bike isn’t enough. It has to be in tip-top shape to be able to perform at its best. And the best way to ensure that is to regularly maintain the bike. A regularly maintained bike will perform better than a bike with better specs but in worse shape.
How fast can a 450cc dirt bike go? How does it fare against bikes of similar or higher capacity? What makes the dirt bike go faster and what needs to be done to reach top speed? All these questions have to be answered before someone can think about choosing whether to go for top speed on their dirt bike or to go for efficiency.
Because dirt bikes prefer maneuverability over speed, they can’t attain top speeds on off-road terrains. So riders have to take everything into account if they want to reach their bike’s maximum speed.