How Fast Does a 125cc Dirt Bike Go? Because We Need It Faster!

Dirt bikes are more than a hundred years old but With the evolution in science and technology, Dirt bikes have evolved significantly too. Whether we are talking about design & body, speed, weight, or engine, everything has been upgraded to give the best results and experience to the rider.

125cc dirt bike
Source: Pexels.com

A 125cc gives an average of 50-60 miles/hour maximum/top speed. A 125cc Dirt bike can go even faster than this with different physical and mental factors. Below listed are some of the factors which can affect the speed of your 125cc dirt bike.

Factors Influencing the speed of a 125cc Dirt Bike 

2-stroke vs 4-stroke engine

A dirt bike has two types of engines. A 2-stroke engine and a 4-stroke engine, both of which have different working and give different results in terms of speed, power, acceleration, and fuel consumption. The upward and downward movement of the pistol in the engine is called a stroke.

  • 2-stroke dirt bike engine

In a two-stroke dirt bike, the engine is started by igniting the fuel with two strokes (The upward and downward movement of the pistol in the engine). Because a two-stroke engine does not require heavy machinery or advanced technology for its functioning, 2-stroke dirt bikes are light weighted and cheaper. They are also convenient and easy to clean due to their simple Designs. The only limitation of a 2-stroke Dirt bike is that they require maintenance on a very regular basis, and also cause heavy pollution to the environment.

  • 4-stroke Dirt bike engine

In a four-stroke Dirt bike, the engine is started by igniting the fuel with four strokes (The upward and downward movement of the pistol in the engine). The four steps involved are intake, compression, combustion, and exhaust. Unlike a two-stroke dirt bike, a four-stroke Dirt bike does not cause much pollution to the environment and gives a manageable power output.

Also, they are easy to ride and are less shifting. A four-stroke Dirt bike involves the use of advanced technology and heavy machinery therefore they are heavier in weight and require skills and experience for riding. Also, though they don’t require maintenance as regularly as a two-stroke dirt bike, the maintenance of a four-stroke Dirt bike is costly as it needs professional assistance.

To know further about the merits and demerits of two-stroke and four-stroke engines, read this article.

Wind drag

Wind drag is one of the Features which affect the speed of a dirt bike. It’s related to aerodynamics therefore not many pay attention to it but a headwind can lead to reduction in the speed of your bike while a tailwind can help you speed up. Side winds do not usually have any effect on the speed of the bike.

Weight of the bike

The speed of your dirt bike reduces if you have a heavy Dirt bike because more power is required to drag a heavy object. This energy can be used to speed up more if you have a light weighted dirt bike. Also, you can reduce the weight of your dirt bike by reducing the number of dirt bike accessories like slime or mousse in the tires (Although it can increase risk).

Weight and height of the rider

The weight and height of the rider also affect the speed of the dirt bike. If the rider is heavy then it adds more weight to the bike and more power and fuel are required to overcome the weight. This energy can be used to speed up more if you have a light weighted rider. The taller the body of the rider, the more push is required through the air and it leads to a reduction in the speed of the Dirt bike.

Rear sprocket

A large rear sprocket leads to more acceleration and reduction in speed. You can increase the speed of your dirt bike by using a smaller rear sprocket. Using smaller rear sprocket results in tall gearing and more speed.

Riders’ skills and experience

The skills and experience while riding a dirt bike also affects the speed of the bike as the rider is the one in charge. If the rider is lacking skills and experience, no matter how good the features of the dirt bike are, it will not deliver the ideal results.

Motocross tracks layout

There are many different types of motocross track layouts. They can be straight, curvy, plain, Muddy, bumpy, rocky, dusty, natural, artificial, with or without obstacles. The speed of the dirt bike also depends on the type of track you are riding. Each track has a different effect on the speed of the dirt bike.

Fast Speed 125 cc Dirt Bikes

KTM 125 SX

KTM 125 SX
Source: KTM.com

The KTM 125 SX is famous for features such as its 6 -speed manual transmission and WP XAct racing suspension. The bike has a 125cc, 1-cylinder, and 2-stroke engine. It has a Kick Start only. It consists of a Multi-plate clutch with Brembo hydraulics. The front suspension is WP XACT-USD, Ø 48 mm and the rear suspension is WP XACT Monoshock with linkage. The front brakes are 260 mm and the rear brakes are 220 mm Disc brakes. The bike has a seat height of 950 mm with a wet weight of 87.5 kg. The model is available in two colors i.e black and orange.

HUSQVARNA TC 125

Husqvarna Bike
Source: HusqvarnaMotorcycles.com

The Husqvarna TC 125 has a two-stroke, single-cylinder engine. It has a Kick Start only. It consists of a Carburettor fuel system, MEDJ digital ignition, and 6 -speed gearbox. The front suspension is WP-USD, AER 48, Ø 48 mm and the rear suspension is a WP shock absorber with linkage. The front brakes are 260 mm, Single disc with Brembo twin-piston floating calipers and the rear brakes are 220 mm, Single disc with Brembo single-piston floating calipers. The bike has a seat height of 950 mm with a dry weight of 87.5 kg. The model is available in three colors i.e Blue, yellow, and white.

YAMAHA YZ 125

Yamaha YZ 125
Source: Youtube.com

The Yamaha YZ 125 has a 125cc liquid-cooled 2-stroke, reed-valve-injected engine. The bike has a Constant-mesh, 6-speed-multi-plate wet clutch. The front suspension is a KYB® Speed-Sensitive System inverted fork and fully adjustable with 11.8-in travel, and the rear suspension is a KYB® single shock and fully adjustable with 12.4-in travel. The front brakes are 270 mm Hydraulic discs, and the rear brakes are 240 mm Hydraulic discs. The bike has a seat height of 38.6 in with a wet weight of 209 lb. 

TM MX 125 2S

TM MX 124
Source: TMRacing.com

The TM MX 125 2S has a Perimetral Aluminum frame. The bike has a Kickstart starting only. It has a 6- speed gearbox. It consists of a  Multiple-disk in an oil bath with a hydraulic control clutch. The bike has a liquid cooling system. The front tyre is 80/100-21 and the Rear tire is 100/90-19. The front brakes are 270 mm with Nissin pump and Braking caliper, disk brakes. And the rear brakes are 245 mm with Nissin Braking pump and caliper, disk brakes. The bike has a fuel capacity of 9.5 L.

Honda CRF 125

Honda CRF 125
Source: UltimateMotorcycling.com

The Honda CRF 125 has a 124.9cc air-cooled 25º, single-cylinder four-stroke engine. It has a constant-mesh and 4-speed return, manual transmission. The bike has a fully transistorized ignition. It has both electric as well as a Kickstart starter. The bike has a Multi-plate clutch. The front suspension is a 31mm conventional telescopic coil-spring fork with 5.2 in. travel. The rear suspension is Pro-Link system w/ single shock and 5.5 in. travel. The front brakes are single 220mm disc, hydraulic brakes. The rear brakes are 95mm leading trail drum Mechanical brakes. The bike has a seat height of 29.1 in. and weighs 194 lbs.

Suzuki DRZ 125

Suzuki DRZ 125
Source: TopSpeed.com

The Suzuki DRZ 125 has a Compact, 124cc, four-stroke, single-cylinder, SOHC, air-cooled engine. It has a wet Multi-plate clutch. The bike has a Telescopic, coil spring, oil damped front suspension, and a link type, coil spring, and oil damped rear suspension. It has a 5-speed constant mesh transmission. The seat height is 775 mm (30.5 in) and the bike weighs 88 kg (194 lbs). It has a fuel tank capacity of 4.8 L. The front tyres are 70/100-17 and the rear tyres are 90/100-14. It has a 5- speed gearbox. The bike has a High rigidity steel pipe frame and a Carburettor. Mikuni VM20SS fuel system.

Beta RR 125 2T

Beta RR Bike
Source: Bike4sale.com

The Beta RR 125 2T has a 2-stroke engine.

Single-cylinder engine. The bike has a digital AC CDI ignition manufactured by Kokusan And Keihin PWK 36mm diameter carburetor intake. The front suspension is a Hydraulic fork with a ø48 mm shaft. The rear suspension is a Monoshock with a progressive compound lever. The front brakes are 260 mm (10.2 inches) single disc brakes. The rear brakes are 260 mm (10.2 inches) single disc brakes. The bike has a Kick Start starter. The seat height is 930 mm (36.6 inches) with a dry weight of 94.0 kg (207.2 lbs). The bike consists of a wet multi-disc clutch and a 5 gear transmission.

To know more about dirt bikes, click right here.

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