Best 4 Stroke Bike Engine Kit To Motorize Your Two Wheels

I love cycling. Yet, every now and then, I love the benefits of an electric bike. Getting an electric bike is simple but if besides cycling you also love mechanics, maybe you’d like to consider getting a 4 stroke bike engine kit to motorize your two wheels.

If you have no clue on why you should do that but fancy the idea, read through this guide. If you already know you want to do it, click on the links below to see which are the best 4 stroke bike engine kits on the market.

Transforming your traditional bike into a motorized vehicle is a load of fun. That is if you have a few mechanic skills. If you’re wondering why not invest in an e-bike from the start, the answer is simple. You already own a bike. By getting only an engine kit, you’ll be able to save a lot of money.

A thing to keep in mind before jumping into the process is to check the laws in your state and make sure that converting your bike into a motorized vehicle comply with the local regulations.

Why Should You Motorize Your Bike?

An electric bike is great for both leisure and commuting. When the distance is long or the slope too steep, you can simply switch to electric aid, reducing the pedaling effort and improving your performance.

In simple words, an electric bike can help you move faster with less effort. But this is not the only reason to motorize your bike. After all, you could invest in a bike that already comes with an engine, saving you the hassle.

Apart from the financial considerations, converting a bike to a motorized vehicle gives you more options in terms of bike features and performance. Moreover, you’ll also be able to choose between electric and gas engines.

As it is clear from the title, this guide is dedicated to the 4-stroke bike engine kits. Although gas engines are less green than electric engines, there are some advantages that made me consider them.

Looking at the dark side, putting an engine on the bike means increasing the weight of your vehicle. If you like pedaling uphill, you might hate the extra weight. But then, you’ll always be able to switch on that engine whenever you feel too tired.

Why Choose A 4 Stroke Bike Engine Kit

On the market, there are many types of bike engine kits. So, why choose a 4-stroke engine? Or why choosing gas in the first place?

To answer these questions, I’m going to start with the latter. If the gas bike engine kits are legal in your area, investing in one could mean a lower initial investment cost compared to the electric models. On the other hand, gas engines are more powerful than electric ones and they don’t need a battery. This usually means that they have a lower weight.

Of course, there are some disadvantages too. Gas engines generate more pollution, they are louder and are generally less discrete than electric engines.

Regarding the types of gas bike engine kits, there are two categories, 2-stroke and 4-stroke engines.

2-stroke engines are usually faster than the 4-stroke models, but they have a long list of disadvantages. They require more mechanical assistance, are louder than their 4-stroke counterparts and require the user to mix gas and oil.

A 4-stroke engine is usually controlled by valves that regulate the inflow and outflow of the fuel. In this way, 4-stroke engines produce more torque and are quieter compared to the 2-stroke engines. They also have a separate oil reservoir and you’ll not have to mix oil and gas anymore.

4-stroke engines also resist longer, produce fewer vibrations and are more comfortable during a ride.

How To Choose A 4 Stroke Bike Engine Kit

  • Terrain: one of the main things to consider when choosing a 4 stroke bike engine kit is the characteristic of the area where you live. If the terrain is flat, a smaller engine could be sufficient. If the area where you live is hilly, consider a larger motor that can generate more torque.
  • Speed: when choosing the bike engine kit, you should also consider the top speed you’re aiming to reach. Larger motors reach higher speeds, but remember to check the legislation in your area if you want to ride legally. Since the whole purpose of installing a motor on the bike is that of having only some support, I’d say you should go with the smallest motor that is right for you, considering your weight and the terrain.
  • Torque: a motor with a higher torque is suitable for hilly terrains or heavy riders. This characteristic is less important on flat terrains.
  • Your weight: yes, you read it right. Your weight is a thing to consider when choosing the motor. If you weigh less than 200 lbs., pick the smallest motor size that matches the characteristics of the terrain. For average riders, a 50cc motor is usually just right. If you weigh more than 200 lbs., go for a motor of at least 60cc. You can still choose a smaller motor if you are happy to achieve lower top speeds.

Best 4 Stroke Bike Engine Kit To Motorize Your Bike

1. 49cc Flying Horse 5G Pull Start Bicycle Engine Kit- 4 Stroke

If you’re an average rider, riding on mainly flat terrains, the Flying Horse 5G Pull Start Bicycle Engine Kit- 4 Stroke might be the right bike engine kit.

This kit contains a 49cc motor that features a centrifugal clutch and pull start enhancements designed to start the engine faster, compared to its older versions. This 4 stroke engine is easy to start with just a starter pull and a hit on the throttle.

49cc Flying Horse 5G Pull Start Bicycle Engine Kit- 4 Stroke

The engine is also equipped with an automatic transmission, which is ideal for those looking for a reliable and easy to use kit. Moreover, you’ll also be able to forget about premixing oil and fuel thanks to the separate oil reservoir.

With this engine on, your bike will become similar to a scooter, with the advantage of being able to exercise or ride your bike without aid whenever you please.

Things We Liked
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    Perfect for commuters: this 49cc 4 stroke bike engine kit is perfect for commuters and not only. The engine will help you get to your destination faster and with less effort.
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    Easy to start: the engine features a centrifugal clutch and a pull start that starts in seconds. Particularly useful if you want to switch between modes while riding.
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    Automatic transmission: this engine is similar to that of a scooter and is equipped with automatic transmission that changes the gears as needed.
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    Long life: thanks to the separate oil reservoir, your engine will stay lubricated at all times. This increases the motor’s lifespan.
Things We Didn't Like
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    This 4 stroke bike engine kit doesn’t come with paper instructions.

2. Flying Horse 49cc 5G Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke

Flying Horse 49cc 5G Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke

The 49cc 5G Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke by Flying Horse is a compact 4 stroke bike engine kit designed to fit on almost all bikes with standard tires. Moreover, this is a friction drive motor that mounts directly over the wheel and not on the frame.

There are many advantages in mounting the engine over the wheel rather than in the center of the frame. In fact, this engine is more discrete on the bike and it doesn’t really change its aesthetics.

Thanks to this feature, it is also easier to mount the engine on a wider range of bikes, including bikes that have non-standard frames.

Moreover, because the engine mounts over the wheel, you’ll not have to install a rear drive sprocket on the bike.

Things We Liked
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    Speed: this 49cc 4 stroke engine is designed to reach speeds of 15 mph. It boasts 4 horse power and it can travel up to 100 miles per gallon.
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    Easy to mount: the engine kit mounts over the wheel and it is easier to install compared to the other models.
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    Compatibility: thanks to the mounting characteristic, the engine kit is compatible with almost all bikes with standard tires. It is compatible tires up to 3 inches wide.
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    Size: the engine is compact and discrete. It measures 9x9,5x7 inches and it won’t have a major impact on the aesthetics of the bike.
Things We Didn't Like
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    The engine kit can be delivered incomplete.

3. Flying Horse 38cc Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke

If you live in an area with flat terrain, then a 38cc 4 stroke engine might deliver enough power for your needs. In this case, an engine kit to consider is the Flying Horse 38cc Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke.

This 4 stroke bike engine kit is part of the Lock-N-Load friction drive kits manufactured by Flying Horse. One of the main advantages of the kit is that it mounts over the wheel and it is, therefore, compatible with a wide range of bikes.

Flying Horse 38cc Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke

In fact, the engine kit is suitable for bikes with non-standard frames, such as women’s bikes, touring or cruiser bikes. The engine is compact and designed to become a discrete presence on the bike. The gas tank is built right on the engine, minimizing the aesthetic impact.

Thanks to the over the wheel installation, the engine will also help you avoid installing a rear drive sprocket.

Things We Liked
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    Compact design: this friction drive bike engine kit has a compact design that fits discretely over the wheel. In detail, the engine measures 8x10x9,5 inches.
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    38cc: this engine is perfect for riders living in an area with flat terrain. Despite its capacity, the engine can reach over 15 mph in a blink of an eye.
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    Fuel consumption: you’ll be able to travel around 100 miles with one gallon of fuel.
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    Air cooled: the engine uses an air cooling system that prevents it from overheating. This prolongs the engine’s lifespan.
Things We Didn't Like
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    The engine doesn’t have enough power to move the bike on hilly terrains.

4. 49cc Flying Horse 5G 4-Stroke Bicycle Engine Assembly Motor + Carb + Exhaust

49cc Flying Horse 5G 4-Stroke Bicycle Engine Assembly Motor + Carb + Exhaust

This 49cc Flying Horse 5G 4-Stroke Bicycle Engine Assembly Motor + Carb + Exhaust is not a complete 4 stroke bike engine kit. The package only contains the assembly motor, the carburetor, and the exhaust, but the transmission and other components are not included.

Nevertheless, this is a great replacement kit for a 49cc pull start bike engine kit if you only have to replace one of the listed components.

The components included in the purchase are also compatible with transmissions manufactured by other brands, as long as they comply with the Flying Horse’s specifications.

The engine uses a forced air displacement cooling system and its 49cc provide 10.2 KW of power. The motor can reach 15 mph in a blink of an eye and it has a great performance on hilly terrains.

Things We Liked
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    Capacity: the engine is powerful enough to move the bike uphill and it is suitable for overweight riders.
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    Compatibility: the engine, carburetor, and exhaust included in this package are also compatible with parts manufactured by different brands.
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    Reliability: Flying Horse is a reliable bike engine kits manufacturer. Its products are made to last and the engines usually have long lives.
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    Cooling system: the engine has a forced air displacement cooling system that prevents the overheating.
Things We Didn't Like
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    It is easy to get confused and mistake this package for a full bike engine kit.

5. GOWE 4-Stroke 49cc Gas Motorized Bike Engine Kit

GOWE 4-Stroke 49cc Gas Motorized Bike Engine Kit is a reliable 4 stroke bike engine kit to consider if you want to motorize your two wheels. This bike engine kit boasts a 49cc pull start engine that is easy to mount on the frame.

The motor is reliable, quiet, and durable. It reaches a top speed between 27 and 32 mph, depending on the characteristic of the terrain and rider’s weight, while the gas tank has a capacity of 2 liters.

GOWE 4-Stroke 49CC GAS PETROL MOTORIZED BICYCLE

This bike engine kit contains everything needed for mounting and installation, including universal brackets and other required hardware. It is suitable for bikes with 26-inch frames or similar bikes, although it might not fit on models with non-standard frames.

The engine has a single bore & stroke cylinder and it is air cooled. Thanks to the torque, displacement, and compression ratio, this engine is designed to provide a superior performance when compared to similar models available on the market.

Things We Liked
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    Top speed: despite having only 49cc, this engine is capable of reaching a top speed between 27 and 32 mph.
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    Air cooled: to prevent overheating, the engine is cooled by air when traveling. The system is great because it doesn’t require any cooling liquids.
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    For adult bikes: the engine is compatible with almost all adult bikes with a 26-inch frame or similar models.
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    Easy to mount: the kit includes all parts and components necessary for mounting a fully functional kit.
Things We Didn't Like
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    This 4 stroke bike engine kit is expensive. Unless you’re planning to transform your bike into a scooter, the price is unjustified.

Conclusion & Final Pick

Choosing the best 4 stroke bike engine kit is often a hassle. You have to consider your weight, the terrain, and a bunch of other variables. Nonetheless, in my opinion, the 49cc 5G Lock-N-Load Friction Drive Bicycle Engine Kit- 4-Stroke by Flying Horse is the best.

This bike engine kit impresses with its characteristics. It contains a friction drive engine which is mounted over the rear wheel. In this way, it doesn’t occupy the space on the bike’s frame, which is a great advantage. Moreover, the engine has a capacity of 49cc and it can reach a speed of 15 mph even on hilly terrains.

All this, together with the fact that it has a minimal impact on the aesthetics of the bike, make me consider it one of the bests on the market. What do you think? Is this a 4 stroke bike engine kit you would consider?

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