9 Best Bicycle Motor Kits | Torque You Can Feel In Your Chest

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The biggest displacement and the highest weight in this lineup, and the two are related.

At 26.4 pounds this is the heaviest kit on the list, and the comparison with the Ktaxon hub kit is the clearest way to see what that means — the Ktaxon comes in at 21.4 pounds on the same scale. That gap is the physical reality of a cast-metal engine, fuel tank, and exhaust versus an electric hub. What you trade for it is range without a charging cable: the kit carries a 3L black teardrop fuel tank rated at 2.5L of fuel per 100km.

Under the tank sits a 2-stroke single-cylinder gasoline engine rated at 2kW at 6500rpm, fed by CDI ignition (a capacitor discharge setup that fires the spark without moving breaker points) and started by foot pedal. The drive side runs a 44-tooth sprocket with a 110-knot chain across 36 spokes. Engine displacement of 100cc sets the general power class — more cc means more pull, which is why this engine has a stronger reputation for torque than smaller kits in the same family.

Owners who keep it running tend to be the ones who respect the break-in. Owners put it this way: “iv had this kit for 5 months now, iv rode the bike pretty hard and the only problem I had was the chain tentioner, I bought the case mounted spring one and it runs flawless.” That experience is the pattern, not the exception — a well-assembled unit with an upgraded tensioner keeps going. First-time builders often find it harder than the listing suggests, and the honest read is that this is a kit for someone with a wrench set and patience, not a plug-and-play install. One buyer’s verdict lands the tone: “It’s not bad if you don’t mind the speed and vibrations.”

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A noiseless gearless hub that swings the weight balance back toward your charging port.

The number that sells this kit is on the scale. At 21.4 pounds it undercuts the IMAYCC 100cc gas kit’s 26.4 pounds, which matters the moment you have to lift the bike onto a rack. The trade you accept is a battery. Ktaxon does not include one, so the total build cost depends entirely on the pack you supply, and the kit expects 48V.

The motor itself is a 48V 1000W brushless, gearless hub — gearless meaning fewer moving parts inside the wheel to wear, at the cost of slightly lower torque from a standstill. It fits most 26-inch bikes with 3.93 inches of front dropout spacing, wraps the rim in lightweight aluminum alloy, and runs 36 high-carbon steel spokes rated for a 220-pound rider. A Pedal Assist Sensor reads your pedaling cadence and feeds power without you touching the throttle, and the LCD screen shows battery level, speed, mileage, mode, and error codes so you can troubleshoot without guessing. Four modes cover it: throttle, presets, pedal assist, and manual.

What buyers praise most is the install itself — a smooth bolt-on build with video help and a kit that plays nicely with a 48V battery. The recurring gripe is durability at the controller end, and it is worth naming honestly: occasional units have arrived that rattled and resisted the wheel, so buy from a seller with a clear return path and test the motor’s direction before you mount the tire. The written instructions have odd translations, so lean on the videos. Long-term riders rate it highly, with one calling it “a must to buy for your bike.”

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A smaller sprocket and a bigger bore, aimed at riders who want a fiddly build on a shoestring.

Two details separate this from the bigger 100cc kits. First, the sprocket: 36 teeth against the 44 teeth you will find on the IMAYCC 100cc kit. Fewer teeth on the rear gear means a taller final ratio, which is the usual way builders chase top speed at the expense of low-end pull. Second, the cylinder: a single-piece 50mm bore head, which the maker says increases load carrying capacity and reduces operating temperature.

The rest of the package is a complete conversion — a 2-stroke, air-cooled, single-cylinder engine, an adjustable high-performance carburetor with a rocker on the handlebar for on-the-fly mixture control, a red high-speed carburetor, and an upgraded capacitor discharge ignition. Four bolts tie the engine to the frame. The instructions walk through each assembly step, and the maker asks you to add lubricant to the cylinder before the first start — skip that and you risk a dry first stroke.

It fits most 26-inch to 28-inch V-frame bikes, mountain and road and cruiser shapes alike. Build quality lands where you would expect at this position on the list: owners are generally pleased with the result, with the recurring notes being a small pin hole in the gas tank on a unit or two and a foot pedal that broke on another. Neither is a systemic flaw, but both point to the same lesson — check every connection before your first ride and expect to fettle small parts.

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Quiet for a two-stroke, and built to carry more weight than most frames will allow.

The load rating is the standout figure — the maker lists support for up to 440 pounds, which is far above the 220 pounds the Ktaxon electric kit rates its wheel for. The engine uses a durable aluminum block with reinforced iron components, and the maker equates that to a sturdier build for heavier riders or a rider hauling cargo.

Noise is the second reason this one stands out. The maker rates operation at roughly 75 dB — the sound level of a normal conversation, which is unusually restrained for a two-stroke. A UV-resistant black tank cuts fuel evaporation, and the maker quotes approximately 100km of range per 0.66 gallons, with a 0.53-gallon tank on the bike. Rounded edges are there to prevent scratches, and the sandblasted, painted surfaces are meant to hold up over time.

Top speed is listed at 28 MPH. Install is designed for V-frame bikes and includes all hardware, but the honest pattern in owner experience is this: you will spend more time reading the manual than bolting parts on, and anyone without prior motorcycle knowledge will find the instructions confusing. The recurring advice from people who have done the build is to swap the sprocket and tensioner bolts for new hardware with threadlocker before your first ride, and to fit a new chain. Speed tolerance matters too — one rider with a 100cc engine measured about 25 MPH, well under the maker’s 28 MPH figure.

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The largest displacement in the lineup, with jetting notes that suggest it rewards a tinkerer.

Displacement is where this kit separates itself. It runs a 110cc engine with a bore of 52mm and a stroke of 40.2mm, delivering a maximum of 3.8Kw at 6000rpm, which the maker pegs at roughly 5.5 to 6.5 horsepower. That is the largest displacement here, and the maker claims 150 miles per gallon on top of it.

Fuel economy at that figure comes from the engine’s efficiency, but the maker is upfront that running it too long without attention can score the cylinder — the bore and stroke come together at the piston face where heat builds. The rule the maker sets is a mix of gasoline and two-stroke oil at 18:1 for new units, and lubricant oil added before every single start. Either two-stroke oil or general engine oil is acceptable for that lubrication. Air-cooling means no radiator to maintain, and the unit weighs 25.9 pounds.

The tuning reviews here are unusually detailed, and they tell you something honest about the kit’s ceiling. One owner reports that with a 66 main jet — the fuel-metering nozzle inside the carburetor — the engine revs to 7,000 RPM under load, reaching 28mph on a small wheel, and 11,500 RPM free revving. The stock jet, by contrast, held it to 5,000 RPM and 20mph. Clutch-in with no load, it hit 12,000 RPM. That is a kit with headroom, but you have to be willing to swap jets and pay attention to jetting to reach it.

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The value engine — cheap to buy, rebuildable, and full of upgrade potential.

This is the little brother to the 100cc IMAYCC kit, and it shares that kit’s frame requirements: 10 inches or more of clearance between the bottom bracket and the top bar of a 26-inch to 28-inch V-frame bike. Its engine is a 2-stroke, 80cc single-cylinder unit rated at 2.1Kw at 5000rpm, running a 44-tooth sprocket and a 110-knot chain on 36 spokes. It carries a 2.5L black teardrop tank.

The fuel story is straightforward: 90-octane gasoline mixed with engine oil at 16:1 when new and 20:1 after the first 500km of run-in riding. On a smooth road at 20-25Km/h, the maker quotes 2 to 2.5L per 100km of fuel consumption. Slower than the 100cc kit, and lighter on the wallet as a result.

There is one clear cultural fact about this kit that experienced builders repeat: it is a base engine meant to be modified, not ridden stock. The tweaks that show up again and again are an upgraded carburetor and exhaust, a 32-tooth sprocket for higher top speed, and a piece of inner tube under the engine mounts to damp vibration. The chain is the part that bites builders — it is wider than a standard bicycle chain, so a standard chain breaker will not cut it, and it needs careful alignment plus a good tensioner, since the stock one is a known weak spot. The 80cc displacement means less power than the 100cc kits, but proportionally less heat and stress too, and the seller’s 30-day return window softens the learning curve. Test-fit everything on the frame before you commit to tightening.

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A 1500W hub at a 20-inch wheel — small diameter, big climbing torque.

A 20-inch wheel mated to a 1500W hub is a specific recipe: smaller tires spin up faster and multiply torque at the contact patch, which is why this combination turns up on fat-tire and snow builds. The motor is brushless and gearless, rated at over 82% efficiency, and built from rust-resistant rubber, stainless steel, aluminum, and copper. The load rating sits at roughly 330.69 pounds, well above the 220 pounds the Ktaxon wheel is rated for.

Control is thoughtful for the price. A Pedal Assist Sensor takes over the pedaling, cycling, and climbing load, cutting fatigue on long climbs. The LCD shows speed, battery level, mode, and faults, so you get warning before a problem strands you. A power-off brake lever kills the motor the instant you squeeze the brakes, and the widened 3.94-inch rubber wheel improves grip — a real benefit when you are running wide tires on loose ground. Add 7 gears and both commuting and short-distance riding are covered.

Owner experience centers on two things: reliability and how straightforward the install is. The kit is wiry but plug-and-play, and the controller is beefier than typical generic units, with max current and model printed right on it. Top speed reports run around 35mph when paired with a 48V 20Ah battery, open up and with the wheel lifted. The honest gaps are axle dimensions not being listed — buyers fit spacers to line up disc rotor and caliper — and the controller offering only a single 2-pin JST-SM light output when some riders want two 4-pin connectors. The stock throttle also tends to stick, and the wiring benefits from additional waterproofing if you ride in rain.

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The most powerful kit here — a 72V system built for riders who want speed and range together.

This is the ceiling of the lineup: a 72V 2000W rear hub motor that lands at the top of the power range. The comparison to the 1500W kit above is stark — 2000W versus 1500W, and 72V versus 48V. Higher voltage means the chain of current flows with more push, which is why a 72V build can hold speed on a long straight where a 48V setup starts to sag.

The hardware backs it up. A 48-72V 45A controller with 18 MOSFETs (the electronic switches inside the controller that handle the load) runs sine wave, which smooths the current into a quieter, cooler feed than a square-wave controller. The MTX33/39 double-wall alloy rims resist denting under the motor’s weight, and the SW900 multifunction display gives you speed, battery level, and mode readouts. A 7-speed freewheel comes included, and the kit ships with a charger. The default shipped configuration is 72V, but the controller accepts 48V too, and you can change the voltage setting from the display.

The owner data on this pick is small but enthusiastic. One long-term rider reports 400 miles on this 2000W 72V 24-inch rear hub setup mounted on a 2005 Giant Stiletto, with a 200-pound, 6-foot-2 rider reaching 45mph easily and covering 60 to 80 miles round trip at 15mph in eco mode with pedal assist and a 20Ah 72V battery. The hub is described as super quiet. The one honest limitation is a fitment note: this is a 135mm dropout rear hub, so measure your frame’s dropout spacing before buying, and the kit also expects a rim brake, not a disc. Anyone with a standard-width frame will need to look at the 1500W kit instead.