We researched and compared the top small engine kits for bicycles, evaluating manufacturer specifications, published safety standards, and aggregated owner feedback from hundreds of users. Our goal is to help you choose a reliable, legal, and safe motor for your bike conversion. Below are our top picks, each with honest strengths and limitations.
| Photo | Product | Score | Buy |
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BikeBerry 80cc 2-Stroke Bicycle Motor Kit Best Overall 80cc, 2-stroke, air-cooled, 40-50 mph top speed |
9.0 | 🛒 Check Price |
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Grubee Skyhawk 66cc 2-Stroke Bicycle Engine Kit Best Value 66cc, 2-stroke, air-cooled, 35-45 mph top speed |
8.7 | 🛒 Check Price |
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Bicycle-Engine.com 49cc 4-Stroke Motor Kit Best 4-Stroke 49cc, 4-stroke, air-cooled, 25-35 mph top speed |
8.4 | 🛒 Check Price |
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Flying Horse 80cc 2-Stroke Bicycle Motor Kit Best for Hill Climbing 80cc, 2-stroke, high-compression head, 45-55 mph top speed |
8.1 | 🛒 Check Price |
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Zeda Firestorm 80cc 2-Stroke Bicycle Engine Kit Best Performance 80cc, 2-stroke, balanced crank, 50-60 mph top speed |
8.8 | 🛒 Check Price |
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Bikemaster 50cc 4-Stroke Bicycle Engine Kit Best for Beginners 50cc, 4-stroke, automatic clutch, 20-30 mph top speed |
7.8 | 🛒 Check Price |
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Cooing 80cc 2-Stroke Bicycle Motor Kit Budget Pick 80cc, 2-stroke, basic components, 35-45 mph |
7.3 | 🛒 Check Price |
1. BikeBerry 80cc 2-Stroke Bicycle Motor Kit: Best Overall
Based on owner feedback and the spec sheets, the BikeBerry 80cc kit delivers robust performance for riders seeking a true motorized bicycle experience. Its 2-stroke engine provides plenty of torque for hills and speeds up to 50 mph, making it a favorite among enthusiasts. The kit includes quality components like a machined cylinder and a reliable CDI ignition system, which we compared favorably against other budget kits. However, the 2-stroke design means you must mix oil with fuel, and the engine can be noisy and smoky.
This kit is not ideal for noise-sensitive neighborhoods or riders wanting a low-maintenance option. If you prefer a cleaner, quieter ride, consider a 4-stroke kit instead. Also, local laws may restrict 2-stroke engines on bicycles, so check regulations before buying.
- Powerful 80cc engine with reliable pull-start and centrifugal clutch.
- Includes all mounting hardware, fuel tank, chain, and exhaust.
- Compatible with most standard bicycle frames (26-29 inch wheels).
Pros: Strong acceleration and hill-climbing ability.; Comprehensive kit with clear instructions.
Cons: 2-stroke engine requires premixing oil and gas.
2. Grubee Skyhawk 66cc 2-Stroke Bicycle Engine Kit: Best Value
In our evaluation of budget-friendly options, the Grubee Skyhawk 66cc stands out for its balance of performance and affordability. Based on aggregated owner feedback, this kit is known for starting easily and running smoothly after a proper break-in. The 66cc displacement offers a good compromise between power and fuel efficiency, making it suitable for commuting and recreational riding. We compared its components to those of pricier kits and found the quality to be satisfactory for the price point.
However, riders seeking maximum speed may find the 66cc underwhelming. Also, like all 2-strokes, it requires oil mixing and emits exhaust smoke. If you need a quiet, low-maintenance motor for daily use, this may not be the best choice. We recommend it for hobbyists on a budget who don’t mind tinkering.
- Proven 66cc engine with improved porting for better fuel efficiency.
- Upgraded NT carburetor and high-performance spark plug.
- Steel mounting bracket and heavy-duty chain included.
Pros: Excellent value for the price: reliable and well-reviewed.; Better fuel economy than many 80cc kits.
Cons: Lower top speed compared to 80cc kits.
3. Bicycle-Engine.com 49cc 4-Stroke Motor Kit: Best 4-Stroke
For riders who prioritize quietness and low maintenance, the 49cc 4-stroke kit from Bicycle-Engine.com is a top contender. We researched its compliance with EPA standards and compared it to other 4-stroke kits; its noise level is significantly lower than 2-strokes, and it runs on regular gasoline without oil mixing. Owner feedback highlights its reliability and ease of starting, even in cold weather. The kit includes a robust mounting system and a fuel tank that fits most frames.
That said, the 49cc engine produces modest power, making it less suitable for steep hills or high-speed cruising. If you need a motor for flat terrain and want to avoid the hassle of 2-stroke maintenance, this is a solid pick. But performance enthusiasts will likely find it underpowered.
- Quiet 4-stroke engine with automatic centrifugal clutch.
- Separate oil system: no premixing required.
- EPA compliant and street-legal in many areas.
Pros: Very quiet and clean operation.; Easy to maintain and fuel.
Cons: Less power than 2-stroke kits of similar displacement.
4. Flying Horse 80cc 2-Stroke Bicycle Motor Kit: Best for Hill Climbing
The Flying Horse 80cc kit is designed for riders who tackle challenging terrain. Based on manufacturer specs and owner reviews, its high-compression head and tuned exhaust deliver strong low-end torque, making hill climbing easier than with standard kits. We compared its power output to similar 80cc engines and found it superior in torque, though top speed is similar. The kit includes performance upgrades that enthusiasts appreciate.
However, the aggressive tuning leads to increased vibration and noise, which can be uncomfortable on long rides. Some owners report that the engine requires frequent tightening of bolts. If you ride mostly flat roads or value comfort, this kit may be too harsh. It is best for off-road or hilly areas where raw power is needed.
- High-compression cylinder head for increased torque.
- Reinforced crankcase and heavy-duty bearings.
- Includes upgraded carburetor and expansion chamber exhaust.
Pros: Exceptional torque for steep hills.; Aftermarket-compatible parts available.
Cons: Vibrates heavily at high RPMs.
5. Zeda Firestorm 80cc 2-Stroke Bicycle Engine Kit: Best Performance
In our evaluation of performance-oriented kits, the Zeda Firestorm 80cc stands out for its refined engineering. The balanced crankshaft and precision-machined cylinder result in smoother operation and higher RPMs than many competitors. Based on owner feedback and spec comparisons, it is one of the fastest kits available, with top speeds exceeding 50 mph. The kit includes robust mounting brackets and a reliable CDI ignition.
However, this performance comes at a premium price. Additionally, the 2-stroke engine still requires oil mixing and emits exhaust. If you are a speed enthusiast willing to invest in quality, this kit delivers. But for casual riders, the extra cost may not be justified.
- Balanced and trued crankshaft for smooth operation.
- High-performance cylinder with 6mm intake port.
- Includes CNC-machined mounting hardware and CDI.
Pros: Smooth power delivery and high top speed.; Quality components reduce vibration.
Cons: Price is higher than most 80cc kits.
6. Bikemaster 50cc 4-Stroke Bicycle Engine Kit: Best for Beginners
The Bikemaster 50cc 4-stroke kit is our top recommendation for first-time builders. Based on owner feedback, the kit is straightforward to install, with clear instructions and pre-assembled parts. The automatic clutch means no manual engagement: just twist the throttle and go. We compared its ease of use to other kits and found it the most beginner-friendly. The 4-stroke engine is quiet and runs on regular gas, making it ideal for neighborhoods.
However, the 50cc engine produces only modest power, struggling on hills and limiting top speed to around 30 mph. Experienced riders may quickly outgrow it. If you want a simple, low-hassle introduction to motorized biking, this is a great start. But if you need more performance, look at larger 2-stroke kits.
- Simple installation with pre-assembled components.
- Automatic centrifugal clutch: twist and go.
- Low noise and emissions, legal in many areas.
Pros: Very easy to install and operate.; No oil mixing required.
Cons: Limited power and speed.
7. Cooing 80cc 2-Stroke Bicycle Motor Kit: Budget Pick
The Cooing 80cc kit is the most budget-friendly option we researched. It provides the basic components needed to motorize a bicycle at a minimal cost. Owner feedback indicates that the engine can run well after some tuning, but many users report issues with carburetor adjustment, chain alignment, and loose bolts. We compared its components to higher-priced kits and found inferior casting and thinner mounting brackets.
This kit is best for experienced tinkerers who are comfortable with frequent maintenance and upgrades. It is not recommended for beginners or those seeking a reliable daily rider. If your priority is absolute lowest cost and you have mechanical skills, it can work. Otherwise, spending a bit more on a better kit will save frustration.
- Lowest price among 80cc kits.
- Includes all essential parts: engine, carburetor, chain, sprocket.
- Compatible with standard bicycle frames.
Pros: Very affordable entry point.; Decent power for the price.
Cons: Lower build quality; may need adjustments.
Frequently Asked Questions
Is it legal to put a small engine on a bicycle?
Laws vary by location. In many areas, motorized bicycles are classified as mopeds and require registration, insurance, and a driver’s license. Engine displacement limits (often 50cc or less) and speed limits (usually 20-30 mph) are common. Some states prohibit 2-stroke engines due to emissions. Always check your local regulations before purchasing and installing a kit.
How fast can a motorized bicycle go?
Speed depends on engine size, gearing, rider weight, and terrain. Typical 50cc 4-stroke kits reach 20-30 mph, while 80cc 2-stroke kits can achieve 35-55 mph. Performance kits with tuned exhausts and high-compression heads can exceed 60 mph. However, safety and legal limits often cap speed, and we recommend staying within safe braking and handling capabilities.
How difficult is it to install a bicycle engine kit?
Installation difficulty varies. Most kits require basic mechanical skills and tools like wrenches, screwdrivers, and a drill for mounting brackets. The process typically takes 2-6 hours. 4-stroke kits are generally easier because they have fewer tuning requirements. Beginners should watch online tutorials and follow the manual carefully. Some bike shops may install for a fee.
Do I need to mix oil with gas for a 2-stroke engine?
Yes, 2-stroke engines require a fuel-oil mixture (typically 32:1 or 40:1 ratio) for lubrication. Failure to mix properly can cause engine seizure. Use high-quality 2-stroke oil and measure accurately. 4-stroke engines have a separate oil system and use straight gasoline, which is simpler and cleaner.
Can I use a bicycle engine kit on any bicycle?
Most kits fit standard adult bicycles with 26-29 inch wheels and a diamond frame. Cruiser, mountain, and hybrid bikes work well. Bikes with unusual frame shapes, suspension, or disc brakes may require modifications or adapters. Ensure the bottom bracket has enough clearance for the engine and chain. Always measure your frame before buying.
Our Verdict
After researching and comparing specifications, owner feedback, and safety standards, our top pick is the BikeBerry 80cc 2-Stroke Bicycle Motor Kit for its proven reliability and strong performance. For a quieter, lower-maintenance alternative, the Bicycle-Engine.com 49cc 4-Stroke Kit is an excellent runner-up. Choose based on your power needs and local regulations.
