TrailMaster Powersports

TrailMaster MK125S Pro Series Dirt Bike - 125cc, 4-Speed Semi-Auto

Regular price $1,399.00 USD
Color: Red

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TrailMaster MK125S Pro Series 125cc Dirt Bike - hero view
$1,399.00 USD
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TrailMaster MK125S Pro Series Dirt Bike - 125cc, 4-Speed Semi-Auto


Description

The TrailMaster MK125S Pro Series is a premium mid-size dirt bike built for riders ready to take on serious off-road terrain. Powered by a Zongshen Balanced Shaft 125cc 4-stroke air-cooled engine producing 6.3hp, it delivers a broad, even power band that keeps performance consistent across all gears. The 4-speed semi-automatic transmission with no-stall automatic clutch makes it approachable for newer riders while still satisfying the demands of more experienced ones.

Designed with motocross ergonomics and race-grade suspension - including inverted front fork shock absorbers and a nitrogen air gas rear mono shock - this bike handles rough trails and jumps with confidence. Dual disc brakes front and rear provide reliable stopping power across all terrain types, and the low 29-inch seat height makes it accessible to a wide range of riders ages 12 and up.


Key Features

  • Zongshen ZS125 Balanced Shaft Engine: 123cc, 4-stroke, air-cooled single cylinder producing 6.3hp at 7,500 RPM - smooth power with reduced vibration.
  • 4-Speed Semi-Automatic Transmission: N-1-2-3-4 shift pattern with automatic clutch - no stalling, easy for newer riders to learn on.
  • Electric Start with Kick Backup: Reliable CDI electronic ignition gets you going fast, with a kick starter as a backup option.
  • Inverted Front Fork Suspension (43/45mm): Race-style inverted front shocks deliver superior handling and absorb impacts on rough terrain.
  • Nitrogen Air Gas Rear Mono Shock: Non-adjustable rear suspension tuned for motocross-style riding stability and comfort.
  • Dual Disc Brakes: Front and rear disc brakes provide consistent, responsive stopping power on any surface.
  • Low 29" Seat Height: Designed for smaller to intermediate-sized riders, making it an ideal step-up bike for ages 12 and up.
  • Alloy Wheels and Foldable Handle Levers: High-quality alloy hubs paired with YUANXING tires (60/100-14 front, 80/100-12 rear) and aluminum linkage for durability.
  • Performance Stainless Steel Muffler: Tuned exhaust system enhances engine performance and longevity.
  • Waterproof Wire Harness: Fully sealed electrical system protects against mud, water, and trail debris.

Shipping

This product requires additional shipping. If you'd like a quote before you purchase, fill out the form on this page or email us at service@omahasportsandgames.com for a delivery ETA or to confirm shipping details.


What's Included

  • TrailMaster MK125S Pro Series Dirt Bike

Why You'll Love It

The TrailMaster MK125S Pro Series is engineered for riders who want a capable, confidence-inspiring machine without jumping straight into a full-size motocross bike. The semi-automatic transmission removes the barrier of clutch control, so riders can focus on the trail ahead rather than the mechanics of shifting. TrailMaster's attention to build quality shows in every detail - from the waterproof wire harness to the alloy hubs and stainless steel exhaust - making this a bike that holds up through seasons of hard riding. The race-tuned suspension and motocross-style ergonomics mean it doesn't just look the part; it genuinely performs on dirt, gravel, and trail alike. Whether you're a parent investing in your kid's first real dirt bike or a rider stepping up from a smaller machine, the MK125S Pro Series delivers lasting value and genuine off-road capability.


Product Specifications

View Product Specs
Engine Type Zongshen Balanced Shaft 125, Single Cylinder, 4-stroke, Air-Cooled
Displacement 123cc
Max Power 6.3hp @ 7,500 RPM (±1.5%)
Max Torque 8.8 N·m @ 5,500 RPM (±1.5%)
Compression Ratio 9.0:1
Shift Type N-1-2-3-4, 4-Speed Automatic Clutch
Start Type Electric / Kick Start
Ignition CDI
Transmission Chain Drive
Lubricant 10W/40
Fuel Capacity 0.92 Gal.
Overall Size (L x W x H) 63" x 27" x 42"
Wheelbase 31"
Seat Height 29"
Ground Clearance 10.24"
Minimum Turning Radius 1,900 mm
Front Tire YUANXING 60/100-14
Rear Tire YUANXING 80/100-12
Wheels Steel Rims, High Quality Alloy Hubs
Frame High Quality Steel Frame
Front Fork Inverted Shock Absorbers, 43/45mm
Rear Shock Non-Adjustable Mono Shock
Upper/Lower Connecting Board Alloy
Handle Lever Foldable
Front Brake Disc
Rear Brake Disc
Exhaust Stainless Steel Muffler
Net Weight 149 lbs
Gross Weight 213 lbs
Packing Size 55" x 17" x 33"

 

FAQ

What age and size rider is the MK125S designed for?

The MK125S Pro Series is designed for riders ages 12 and up. With a seat height of 29 inches and a net weight of 149 lbs, it fits younger teens through adults of average stature. It's an ideal step-up bike from smaller youth machines, and also works well as a beginner-to-intermediate adult trail bike.

What does "semi-automatic" mean on this dirt bike?

Semi-automatic means the bike has a 4-speed sequential gearbox that you shift manually with your foot, but there is no manual clutch lever to operate. The automatic clutch engages and disengages on its own, preventing the engine from stalling and making it much easier to learn on compared to a fully manual transmission. You still control when you shift up or down, giving you the control of a gearbox without the learning curve of clutch management.

Does this bike have circular shifting?

No. The MK125S uses a standard N-1-2-3-4 shift pattern. Circular shifting - where shifting up from 4th gear loops back to neutral and then 1st - is not used on this bike. TrailMaster specifically avoids circular shifting configurations on all of their bikes.

Does the bike come assembled or will I need to put it together?

The MK125S ships partially assembled. Some final assembly is required, such as attaching the handlebars, mirrors, and other components. The process is generally straightforward with basic hand tools. Contact us if you have questions about assembly before your order arrives.

How does the MK125S ship?

This bike ships freight on a pallet due to its size and weight (213 lbs gross). It will be delivered by a freight carrier, typically curbside. Please contact us at service@omahasportsandgames.com for a shipping quote or delivery ETA before purchasing if needed.

What fuel and oil does the MK125S require?

The engine runs on regular unleaded gasoline with a fuel tank capacity of 0.92 gallons. The recommended engine oil is 10W/40. Always consult the owner's manual for exact maintenance intervals and specifications.

Product specifications table
Specification name Specification Value
Fuel supply Gasoline
Item condition New
Transmission type Automatic
Vehicle features Headlights, Cargo rack

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