Adding a small gas engine to your bicycle can transform your commute or weekend ride. But with many kits on the market, choosing the right one requires careful research. We compared manufacturer specifications, published safety standards, and aggregated owner feedback to evaluate the most popular options. This guide highlights the strengths and weaknesses of each kit, so you can find a reliable motor that matches your bike and riding style.
| Photo | Product | Score | Buy |
|---|---|---|---|
|
🚗
|
BikeBerry 80cc 2-Stroke Motorized Bicycle Engine Kit Best Overall 80cc 2-stroke, 3.5 HP, top speed ~25 mph |
9.0 | 🛒 Check Price |
 |
Zeda Firestorm 80cc 2-Stroke Bicycle Engine Kit Best Performance 80cc 2-stroke, upgraded crank and bearings, 4 HP |
8.7 | 🛒 Check Price |
|
🚗
|
Briggs & Stratton 35ci 4-Stroke Bicycle Engine Best 4-Stroke 35cc 4-stroke, 1.5 HP, top speed ~20 mph |
8.4 | 🛒 Check Price |
|
🚗
|
Grubee Skyhawk GT5 66cc 2-Stroke Engine Kit Best Value 66cc 2-stroke, 2.5 HP, top speed ~22 mph |
8.1 | 🛒 Check Price |
|
🚗
|
Bikemaster 50cc 2-Stroke Motorized Bicycle Kit Best for Beginners 50cc 2-stroke, 2 HP, top speed ~18 mph |
7.8 | 🛒 Check Price |
 |
Huasheng 49cc 4-Stroke Engine Kit Quiet Runner 49cc 4-stroke, 1.8 HP, top speed ~19 mph |
7.5 | 🛒 Check Price |
 |
Flying Horse 80cc 2-Stroke Bicycle Engine Budget Pick 80cc 2-stroke, 3 HP, top speed ~24 mph |
7.2 | 🛒 Check Price |
1. BikeBerry 80cc 2-Stroke Motorized Bicycle Engine Kit: Best Overall
In our evaluation, the BikeBerry 80cc 2-Stroke Kit stands out for its balance of power and completeness. The CNC-machined cylinder and quality carburetor deliver consistent performance, and owner feedback frequently praises its ease of installation. However, like all 2-stroke kits, it requires mixing oil with fuel, which can be messy for some users. We recommend this kit for riders seeking a proven, all-in-one solution that offers strong acceleration and a top speed around 25 mph.
One real weakness is the vibration at higher RPMs, which can loosen bolts over time. We suggest using thread-locker and checking fasteners regularly. This kit may not be ideal for those who prefer a cleaner 4-stroke experience or who need a quieter ride.
- Complete kit with engine, mounting hardware, and chain
- CNC-machined cylinder for better heat dissipation
- Includes detailed instruction manual and DVD
Pros: Strong power output for hills and acceleration; Good build quality and reliable components
Cons: 2-stroke requires pre-mixing gas and oil
2. Zeda Firestorm 80cc 2-Stroke Bicycle Engine Kit: Best Performance
The Zeda Firestorm 80cc is built for riders who want maximum power. We compared its specs to standard kits and found a stronger cylinder, upgraded crank, and a performance carburetor that deliver noticeably more torque. Owner feedback confirms it climbs hills with ease and reaches speeds over 30 mph with proper tuning. However, this added performance comes with a higher price and more maintenance.
A real limitation is that the engine can be finicky to tune, especially for beginners. It also produces more vibration and noise. We suggest this kit only for experienced builders who are comfortable with carburetor adjustments and who prioritize speed over simplicity.
- High-performance cylinder and piston for more power
- Reinforced crank and bearings for durability
- Comes with performance carburetor and intake
Pros: Excellent power for steep hills and off-road; Upgraded internals handle higher RPMs
Cons: More expensive than standard kits
3. Briggs & Stratton 35ci 4-Stroke Bicycle Engine: Best 4-Stroke
For riders who prioritize reliability and simplicity, the Briggs & Stratton 35cc 4-Stroke engine is a top choice. Based on owner feedback and the spec sheet, it starts easily and runs cleanly on regular gasoline. The 4-stroke design is quieter and produces fewer vibrations, making for a more pleasant ride. However, the power output is modest, topping out around 20 mph, and the engine is heavier than 2-stroke alternatives.
One weakness is that the mounting kit may not fit all bicycle frames, and the added weight can affect handling. We recommend this engine for casual riders, commuters on flat terrain, or anyone who dislikes mixing fuel and wants a low-maintenance setup.
- 4-stroke engine runs on straight gasoline, no mixing
- Quieter and smoother than 2-stroke counterparts
- Reliable starting and low maintenance
Pros: No fuel mixing required; Very durable and long-lasting engine design
Cons: Less power than 2-stroke options; Heavier and may require frame reinforcement
4. Grubee Skyhawk GT5 66cc 2-Stroke Engine Kit: Best Value
The Grubee Skyhawk GT5 is one of the most popular budget kits on the market. In our comparison, we found that it offers decent performance for the price, with many owners reporting satisfactory results after proper break-in. The 66cc engine provides enough power for flat roads and moderate hills. However, the kit’s components, such as the carburetor and spark plug, are often cited as needing upgrades for long-term reliability.
A real weakness is inconsistent quality control; some users receive kits with poorly machined parts. We suggest this kit for budget-conscious builders who are willing to spend time tuning and replacing a few parts. It may not suit those who want a plug-and-play experience or who need maximum reliability.
- Affordable complete kit with all necessary parts
- Widely compatible with most bicycle frames
- Good aftermarket support and replacement parts
Pros: Excellent value for the price; Easy to find parts and online support
Cons: Lower build quality can lead to reliability issues
5. Bikemaster 50cc 2-Stroke Motorized Bicycle Kit: Best for Beginners
The Bikemaster 50cc kit is designed with beginners in mind. We evaluated its installation process and found that the smaller engine size makes mounting and fitting simpler. The lower top speed (around 18 mph) is safer for new riders learning to handle a motorized bicycle. Owner feedback often highlights how quickly they got the kit running.
However, the 50cc engine struggles on steep inclines and with heavier riders. It also may not satisfy those who want more speed. We recommend this kit for first-time builders, light riders, or flat-terrain commuters who want a gentle introduction to motorized biking.
- Smaller engine easier to install and control
- Lower top speed suitable for learning
- Lighter weight reduces strain on bike frame
Pros: Very easy to install even for first-timers; Less intimidating power delivery
Cons: Limited power for hills or heavier riders
6. Huasheng 49cc 4-Stroke Engine Kit: Quiet Runner
The Huasheng 49cc 4-stroke engine is one of the quietest options we researched. Its 4-stroke design and centrifugal clutch make it a good choice for neighborhoods where noise is a concern. The engine runs on regular gasoline and requires minimal maintenance. However, we found that the mounting hardware included in many kits is generic and may require modifications to fit certain bike frames.
A real limitation is the modest power; it accelerates slowly and struggles on hills. Owners also report that the clutch can slip if not adjusted properly. We recommend this engine for flat-terrain riders who value quietness and are comfortable with some DIY fitting.
- 4-stroke engine runs quietly and smoothly
- Separate gas and oil, no mixing required
- Includes centrifugal clutch for easy starts
Pros: Very quiet operation; Smooth power delivery with centrifugal clutch
Cons: Installation can be tricky due to mounting kit
7. Flying Horse 80cc 2-Stroke Bicycle Engine: Budget Pick
The Flying Horse 80cc is the most budget-friendly option in our comparison. It delivers similar power to other 80cc kits but at a lower cost. Owner feedback is mixed: many are satisfied after replacing the stock spark plug and carburetor, while others report issues with the engine mount bolts stripping. We noted that the kit lacks some hardware found in pricier alternatives.
The main weakness is durability; the cylinder and piston may wear faster under hard use. We recommend this kit only for experienced tinkerers who can troubleshoot and upgrade parts. Beginners or those seeking long-term reliability should consider spending more for a higher-quality kit.
- Lowest price among 80cc kits
- Standard 80cc power for hills and speed
- Basic kit includes engine, carburetor, and chain
Pros: Very affordable; Decent power for the price
Cons: Inconsistent quality control, some parts may need replacement
Frequently Asked Questions
Is it legal to add a gas engine to a bicycle?
Laws vary by location. In many areas, a motorized bicycle is considered a moped and requires registration, insurance, and a driver’s license. Some states have engine size limits (often 50cc or less) and speed restrictions (usually under 20-30 mph). Always check your local regulations before installing a gas engine. We recommend starting with your state’s Department of Motor Vehicles website.
What size gas engine is best for a bicycle?
For most riders, 66cc to 80cc 2-stroke engines offer a good balance of power and weight. They can reach 20-25 mph and handle moderate hills. Smaller 50cc engines are easier for beginners but lack hill-climbing power. 4-stroke engines (35cc-49cc) are quieter and more reliable but produce less power. Consider your terrain, weight, and desired speed when choosing.
Do I need to mix oil with gas for a 2-stroke engine?
Yes, 2-stroke engines require a mixture of gasoline and 2-cycle oil. The typical ratio is 32:1 or 40:1 (check your kit’s manual). Mixing ensures proper lubrication of the engine. 4-stroke engines use separate oil in the crankcase, so you only pour straight gasoline into the tank.
How fast can a gas-powered bicycle go?
Top speed depends on engine size, gearing, rider weight, and terrain. Most 66cc-80cc kits achieve 20-28 mph. With performance upgrades, some can exceed 30 mph. 4-stroke engines typically top out around 18-22 mph. Always ride at safe speeds and wear a helmet.
What maintenance does a gas bicycle engine require?
Regular maintenance includes checking and tightening bolts, lubricating the chain, cleaning the air filter, and replacing spark plugs. 2-stroke engines need consistent fuel mixing. 4-stroke engines require periodic oil changes. Over time, the clutch pads and brake pads may need replacement. We recommend inspecting the engine and mounting hardware before every ride.
Our Verdict
After researching specifications and owner feedback, we recommend the BikeBerry 80cc 2-Stroke Kit as the best overall for its reliable power, complete package, and ease of installation. For those who want the highest performance, the Zeda Firestorm 80cc is a strong runner-up with upgraded internals. Choose based on your experience level and riding needs.
