🏁 SYX MOTO MK 40cc 4-Stroke Kids Gas Mini Dirt Bike
Automatic Off-Road Performance. Built for Young Riders.
🏍️ 40cc 4-Stroke Gas Engine • Automatic Transmission • 18.64 MPH • 15.53-Mile Rated Range
The SYX MOTO MK40 is a compact gas-powered mini dirt bike designed for young riders who are ready to move beyond basic ride-on toys and experience real off-road riding.
Its 38.95cc single-cylinder 4-stroke engine, fully automatic transmission, chain drive, front and rear mechanical disc brakes, suspension, and 10-inch tires create a straightforward platform for recreational riding on appropriate private-property and designated off-road terrain.
With a manufacturer-rated 18.64 mph top designed speed, 15.53-mile maximum range, and 132 lb maximum load, the MK40 balances manageable performance with a purpose-built mini dirt-bike chassis.
Important: Manufacturer recommends riders 12+ years old. Adult supervision is required, and riders should always wear appropriate protective equipment.
⭐ Why Choose the MK40?
🔥 38.95cc 4-Stroke Gas Engine
The air-cooled, single-cylinder 38.95cc 4-stroke engine provides gasoline-powered performance without the need for a battery or electric charging system.
⚙️ Fully Automatic Transmission
No manual clutch or gear shifting. The automatic transmission lets the rider concentrate on steering, balance, throttle control, and the trail.
🏁 Up to 18.64 MPH
The MK40 has a manufacturer-specified top designed speed of 18.64 mph (30 km/h), with a built-in speed governor for speed control.
⛽ 15.53-Mile Maximum Range
The manufacturer lists a maximum range of 15.53 miles (25 km) and a 0.27 US gallon / 1.0L fuel tank.
Actual range can vary with rider weight, terrain, riding style, speed, surface conditions, and other operating factors.
🛞 10-Inch Off-Road Tires
The 2.50-10 front and rear tires provide a compact dirt-bike footprint suited to appropriate grass, dirt, and recreational off-road surfaces.
🛑 Front + Rear Disc Brakes
The MK40 uses front and rear mechanical disc brakes, giving the bike braking capability at both wheels.
🪨 Front & Rear Suspension
Front and rear shock absorbers help the chassis handle uneven recreational terrain more comfortably than a rigid mini-bike design.
🧱 Iron Frame Construction
The frame, handlebar, swing arm, and footpegs use iron construction, while the triple clamp and wheel rims use aluminum.
⚡ Key Features
🔥 38.95cc 4-Stroke Engine
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40cc-class gasoline engine
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Actual displacement: 38.95cc
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Single cylinder
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4-stroke
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Air cooled
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Downward cam
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Vertical configuration
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Pull start
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Compression ratio: 9.6:1
Why it matters: A 4-stroke engine provides a conventional gasoline-powered riding experience without the need for an electric charging system.
⚙️ Automatic Chain Drive
The MK40 uses:
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Automatic transmission
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No gears
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Chain drive
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T8F 140L chain
There is no manual clutch or traditional multi-speed gearbox to operate.
🏁 Speed-Controlled Performance
Top designed speed: 18.64 mph / 30 km/h
The bike is equipped with a speed governor designed to limit maximum velocity.
This makes the MK40 a recreational off-road machine rather than a street motorcycle.
🛑 Front & Rear Mechanical Disc Brakes
The braking system uses:
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Front mechanical disc brake
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Rear mechanical disc brake
Dual-wheel braking provides braking capability at both ends of the bike.
🛞 10-Inch Tires
Front:
2.50-10
Rear:
2.50-10
The tires are designed for off-road recreational use and are paired with aluminum/black rims.
🪨 Front & Rear Suspension
The MK40 features front and rear shock absorbers:
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Front shock absorber length: 530mm
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Rear shock absorber: 8x190mm
This suspension setup is intended to help absorb bumps and uneven surfaces during off-road riding.
🧒 Youth-Oriented Size
Manufacturer-recommended rider age:
12+ years
Maximum load:
132 lbs / 60 kg
Seat height:
23.6 inches / 600mm
Handlebar height:
29.9 inches / 760mm
Always consider the rider's physical size, ability, and ability to safely control the motorcycle—not age alone.
📊 Performance Overview
| Performance Specification | MK40 |
|---|---|
| Engine | 40cc-class 4-stroke |
| Actual Displacement | 38.95cc |
| Engine Configuration | Single-cylinder |
| Cooling | Air cooled |
| Starting | Pull start |
| Transmission | Automatic |
| Gears | No gear |
| Drive | Chain |
| Top Designed Speed | 18.64 mph / 30 km/h |
| Maximum Range | 15.53 miles / 25 km |
| Fuel Tank | 0.27 US gal / 1.0L |
| Maximum Load | 132 lbs / 60 kg |
| Front Tire | 2.50-10 |
| Rear Tire | 2.50-10 |
| Front Brake | Mechanical disc |
| Rear Brake | Mechanical disc |
| Front Suspension | 530mm shock absorber |
| Rear Suspension | 8x190mm shock absorber |
| Ground Clearance | 7.9 in / 200mm |
Motor Wattage
Not applicable. The MK40 uses a gasoline engine rather than an electric motor.
Battery
No battery. This is a gasoline-powered dirt bike.
Charging Time
Not applicable. The MK40 does not use a rechargeable battery.
Published Engine Horsepower
Not specified by the manufacturer.
Published Engine Torque
Not specified by the manufacturer.
🌄 Built for Recreational Off-Road Riding
The MK40 is designed around a compact dirt-bike chassis with 7.9 inches / 200mm of ground clearance, 10-inch tires, front and rear suspension, and chain-driven rear-wheel power.
It is suitable for appropriate recreational surfaces such as:
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Dirt trails
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Packed soil
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Grass
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Backyard riding areas where permitted
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Designated off-road riding areas
Hill Climbing
The manufacturer does not publish a specific maximum grade or hill-climbing angle for the MK40.
Actual climbing performance depends on:
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Rider weight
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Terrain
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Surface traction
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Hill angle
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Tire condition
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Riding technique
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Engine condition
For that reason, no unsupported hill-climbing percentage is claimed here.
📐 Full Technical Specifications
| Category | Specification |
|---|---|
| Model Number | KXD708B-1 (MK40) |
| Recommended User Age | 12+ years old |
| Top Designed Speed | 18.64 mph (30KM/H) |
| Maximum Range | 15.53 miles (25KM) |
| Maximum Load | 132 lbs (60KG) |
| Engine Type | 40cc, single cylinder, 4 stroke, air cooled, downward cam, vertical, pull start |
| Displacement | 38.95 cc |
| Bore × Stroke | 40mm |
| Compression Ratio | 9.6:1 |
| Starting Mode | Pull Start |
| Idle Speed | 3000±150 rpm |
| Spark Plug | CM7H |
| Fuel Grade | ≥90# |
| Lubrication Type | Negative pressure splash lubrication |
| Lubrication Oil Grade | SF 10W/30 or equivalent model |
| Carburetor | Engine dedicated |
| Air Filter | Sponge |
| Cooling | Air Cooled |
| Transmission | Automatic |
| Number of Speeds | No gear |
| Drive Mode | Chain |
| Frame | Iron |
| Handlebar | Iron |
| Triple Clamp | Aluminum |
| Swing Arm | Iron plate forming |
| Footpegs | Iron |
| Muffler Type | Engine with exhaust, front exhaust |
| Chain | T8F 140L |
| Wheelbase | 32.3 in / 820mm |
| Ground Clearance | 7.9 in / 200mm |
| Turning Circle Diameter | 51.2 in / 1300mm |
| Seat Height | 23.6 in / 600mm |
| Handlebar Height | 29.9 in / 760mm |
| Brake Operation | Front and rear mechanical disc brakes |
| Front Shock Absorber Length | 530mm |
| Rear Shock Absorber | 8x190mm |
| Front Tire | 2.50-10 |
| Rear Tire | 2.50-10 |
| Front Rim | Aluminum/Black |
| Rear Rim | Aluminum/Black |
| Fuel Tank Capacity | 0.27 US Gallon / 1.0L |
| Bike Dimensions | 48.43 × 23.62 × 31.50 in (1230 × 600 × 800mm) |
| Packing Dimensions | 42.13 × 11.81 × 21.46 in (1070 × 300 × 545mm) |
| Dry Weight | 49.6 lbs / 22.5kg |
| Wet Weight | 51.4 lbs / 23.3kg |
| Shipping Weight | 59.5 lbs / 27kg |
| Curb Weight | 183.6 lbs / 83.3kg |
The manufacturer-published specification sheet confirms these figures.
🆚 How Does the MK40 Compare?
The comparison below uses published specifications from comparable mini dirt bikes. Because manufacturers do not publish identical specification sets, unavailable specifications are marked rather than guessed.
| Specification | SYX MOTO MK40 | MotoTec Demon 40cc | XtremepowerUS 40cc | Razor MX350 |
|---|---|---|---|---|
| Power Type | Gas | Gas | Gas | Electric |
| Engine / Motor | 38.95cc 4-stroke | 40cc 4-stroke | 40cc 4-stroke | 250W electric |
| Engine Cooling | Air | Air | Not specified | N/A |
| Rated Output | Not specified | 1.9 hp @ 6500 rpm | Not specified | 250W |
| Torque | Not specified | 1.6Nm @ 5000 rpm | Not specified | Not published |
| Starting | Pull start | Pull start | Pull start | Electric |
| Transmission | Automatic | Auto centrifugal | Fully automatic | Chain-driven |
| Top Speed | 18.64 mph | 22 mph | Up to 18 mph | 14 mph |
| Published Range/Runtime | 15.53 miles | 20+ miles/tank | Up to 27 miles | 30–60 min |
| Fuel Tank | 1.0L | 1.2L | Approx. 0.32 gal | N/A |
| Maximum Load | 132 lbs | 165 lbs | 165 lbs | 140 lbs |
| Front Tire | 2.50-10 | 2.50-10 | Not specified | 12" pneumatic |
| Rear Tire | 2.50-10 | 2.50-10 | Not specified | 12" pneumatic |
| Front Brake | Mechanical disc | Disc | Not specified | N/A |
| Rear Brake | Mechanical disc | Disc | Rear disc | Hand-operated rear |
| Suspension | Front + rear | Front + rear | Not fully specified | Steel double-crown fork |
| Frame | Iron | Chromoly steel | Steel/aluminum/plastic | Steel |
| Seat Height | 23.6" | 23" | 21.25" | Not published |
| Ground Clearance | 7.9" | 5.3" | Not published | Not published |
| Product Weight | 49.6 lbs dry | Not specified in source | 58 lbs | 48.26 lbs |
| Recommended Age | 12+ | 13+ | 13+ | 8+ low / 13+ high |
MotoTec publishes 1.9 hp, 1.6Nm torque, 22 mph, 20+ miles per tank, 1.2L tank, 165 lb capacity, 23-inch seat height, 2.50-10 tires, front/rear disc brakes, front inverted fork and rear mono-shock for the Demon 40cc.
XtremepowerUS publishes 40cc 4-stroke, pull start, up to 18 mph, 165 lb capacity, rear disc brake, 21.25-inch seat height, 58 lb weight, while another published manual lists an approximately 0.32-gallon tank and up to 27-mile range.
Razor's MX350 is a fundamentally different electric alternative, using a 250W high-torque chain-driven motor, 24V sealed lead-acid battery, 14 mph maximum speed, up to 60 minutes low-speed runtime, 140 lb maximum rider weight, 12-inch pneumatic tires, steel frame, and rear brake.
Why the MK40 stands out
The MK40 combines a 38.95cc 4-stroke gasoline engine, automatic transmission, front and rear mechanical disc brakes, front and rear suspension, 7.9-inch ground clearance, and a 132 lb maximum load in a compact 49.6-lb dry package.
It also offers a higher maximum speed than the published Razor MX350 while retaining an automatic riding format.
🛡️ Safety & Riding Information
The MK40 is an off-road recreational vehicle and should not be treated as a street motorcycle.
Important Safety Requirements
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Recommended rider age: 12+
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Maximum load: 132 lbs / 60kg
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Adult supervision is required.
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Wear a DOT-compliant helmet.
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Wear goggles or appropriate eye protection.
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Wear gloves.
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Wear long sleeves and long pants.
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Wear over-the-ankle riding boots.
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Ride only where this type of vehicle is permitted.
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Never carry a passenger.
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Keep away from public-road traffic.
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Check applicable local laws before riding.
The manufacturer states that the vehicle is intended for off-road recreational use and is not street legal.
📦 What's in the Box?
The manufacturer-provided material supplied for this product does not publish a complete itemized box-content list.
Therefore, we do not claim specific accessories, tools, spare parts, or protective equipment are included unless confirmed by the fulfillment package.
The product does have manufacturer-provided assembly and starting resources.
Important: Helmet and protective riding equipment are not presented as included with the motorcycle.
🔧 Assembly & Getting Started
The MK40 has manufacturer-provided assembly and starting instructions.
Before the first ride:
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Complete the required assembly.
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Check all fasteners.
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Check the brakes.
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Check throttle operation.
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Check tire condition and inflation.
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Check chain condition and tension.
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Check engine oil level.
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Fill with the appropriate fuel.
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Start the engine according to the manufacturer's instructions.
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Perform a controlled test ride in a safe, permitted area.
Always inspect the motorcycle before every ride.
⛽ Fuel & Engine Information
The MK40 uses a 38.95cc single-cylinder 4-stroke air-cooled gasoline engine.
Fuel
Manufacturer specification:
Fuel grade: ≥90#
Engine Oil
Manufacturer specification:
SF 10W/30 or equivalent model
The manufacturer describes the lubrication system as negative-pressure splash lubrication.
Always follow the owner's manual and engine manufacturer's instructions for fluid requirements and maintenance.
💧 Is the MK40 Waterproof?
No waterproof/IP rating is published for the MK40 in the manufacturer's specifications.
This means we do not recommend treating the motorcycle as waterproof or intentionally exposing it to heavy water, flooding, pressure washing, or prolonged wet conditions.
After riding in wet conditions, inspect and maintain the bike according to the manufacturer's instructions.
🔋 Does It Need Charging?
No.
The MK40 is gasoline powered and does not use a rechargeable battery.
There is therefore:
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No battery voltage
-
No battery Ah rating
-
No charging time
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No electric motor wattage
Instead, the motorcycle uses a 0.27 US gallon / 1.0L gasoline tank and a 38.95cc 4-stroke engine.
❓ Frequently Asked Questions
1. How fast does the SYX MOTO MK40 go?
The manufacturer lists a top designed speed of 18.64 mph / 30 km/h.
Actual speed can vary depending on rider weight, terrain, conditions, and operation.
2. How far can it travel on one tank?
The manufacturer lists a maximum range of 15.53 miles / 25 km.
Actual range varies depending on riding conditions, rider weight, terrain, throttle use, and speed.
3. Does the MK40 have gears?
No. The motorcycle uses a fully automatic transmission with no gears.
4. What age is the MK40 designed for?
The manufacturer's recommended user age is 12+ years old.
Rider size, skill level, and ability to safely control the motorcycle should also be considered.
5. How much weight can it carry?
Maximum load is:
132 lbs / 60 kg
Do not exceed the manufacturer's maximum load specification.
6. What size tires does it use?
The MK40 uses:
Front: 2.50-10
Rear: 2.50-10
7. Does it have suspension?
Yes.
The MK40 has front and rear shock absorbers.
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Front: 530mm
-
Rear: 8x190mm
8. What type of brakes does it use?
The MK40 uses front and rear mechanical disc brakes.
9. Can it be ridden on the street?
No.
The manufacturer identifies the MK40 as an off-road recreational vehicle and states that it is not street legal. Always check local regulations before operating the vehicle.
10. Is the MK40 electric?
No.
It is powered by a 38.95cc gasoline 4-stroke engine.
11. Does it require battery charging?
No. There is no rechargeable traction battery.
12. Can it climb hills?
The manufacturer does not publish a maximum hill-climbing angle.
Climbing ability depends on terrain, grade, traction, rider weight, speed, and riding conditions.
13. Is it waterproof?
No IP/waterproof rating is published by the manufacturer. Avoid treating the bike as waterproof or exposing it to unnecessary water.
14. Is assembly required?
The product has manufacturer-provided assembly resources. Complete all required assembly and pre-ride checks before operation.
🚚 Shipping
USA Shipping
The manufacturer states that the MK40 ships to 47 continental U.S. states.
California is excluded.
Processing
Usually:
1–2 business days
Shipping
Usually:
1–5 days
Shipping Fee
Listed shipping fee:
$99.99
Actual delivery time can vary based on carrier and destination.
🛡️ Warranty
The manufacturer's published warranty terms state:
Engine Warranty
3 months against manufacturer defects.
Parts Warranty
1 month against manufacturer defects.
Arrival Damage
Damage on arrival should be reported within 3 business days of delivery.
Warranty coverage applies to manufacturer defects and does not automatically cover damage caused by misuse, accidents, improper maintenance, modification, or normal wear.
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📦 Tracked Shipping
Shipping is handled through established delivery carriers, with delivery timing dependent on destination and carrier conditions.
🧰 Product Support
Manufacturer documentation and product support resources are available for the MK40.
🔍 Product Information
Specifications on this page are based on manufacturer-published information. Where a specification is not published, we clearly identify it rather than estimating.
🏁 Ready for the Trail?
The SYX MOTO MK40 brings genuine gasoline-powered dirt-bike design into a compact youth-oriented package.
With its 38.95cc 4-stroke engine, automatic transmission, 18.64 mph top designed speed, 15.53-mile manufacturer-rated maximum range, front and rear mechanical disc brakes, front and rear suspension, 2.50-10 tires, 7.9-inch ground clearance, and 132 lb maximum load, it is built for recreational off-road riding without the complexity of a manual transmission.
Choose your color and get the SYX MOTO MK40 ready for your next off-road adventure.
Ride responsibly. Wear protective gear. Follow local laws. Adult supervision required.