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Cross - Motocross · 2021

MC 125

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MotoLibrary Score
46 /100 Balanced
Power/Weight
0.46 hp/kg
Engine
125 ccm

2021 Gas Gas MC 125 Technical Analysis & Specification Breakdown

Positioned in Gas Gas's cross - motocross motorcycle lineup, the 2021 Gas Gas MC 125 utilizes a 124.8 cc (7.6 cu in) single cylinder, two-stroke layout. In factory specification, peak output is rated at 40 HP (29.2 kW), transferring power to the rear wheel through a 6-speed gearbox and chain final drive. With a specific output of 320.5 HP per liter, the engine character is placing it firmly in high-revving supersport territory where top-end breathing dominates.

On the scales, the MC 125 measures 87.5 kg (193 lbs) dry, translating to a power-to-weight ratio of 0.46 HP/kg (2.19 kg per horsepower). Rider ergonomics and chassis geometry center around a 950 mm (37.4 in) seat height — reflecting a long-travel chassis stance that favors ground clearance and off-pavement control, combined with a 1,475 mm (58.1 in) wheelbase engineered for balanced agility and highway composure. The 7-liter (1.8 US gal) fuel tank supports practical everyday commuting and weekend road stints.

Within MotoLibrary's Gas Gas archive, this model family spans 8 indexed model years from 2004 to 2025, allowing buyers to track year-over-year changes in emissions tuning, weight and equipment.

Specific Output
320.5 HP/L
Power-to-Weight
0.46 HP/kg (2.19 kg/HP)
Standover Height
950 mm (37.4 in)
Engine
Displacement 124.8 ccm (7.62 cubic inches)
Engine Type Single cylinder, two-stroke
Power 40.0 HP (29.2 kW))
Bore x Stroke 54.0 x 54.5 mm (2.1 x 2.1 inches)
Fuel System Carburettor. Mikuni TMX
Ignition Kokusan EMS
Transmission
Gearbox 6-speed
Final Drive Chain (final drive)
Clutch Wet multi-disc DS clutch, Brembo hydraulics
Chassis
Frame Type Central double-cradle-type 25CrMo4 steel
Rake 26.1°
Front Suspension WP XACT-USD, Ø 48 mm
Front Travel 310 mm (12.2 inches)
Rear Suspension WP XACT Monoshock with linkage
Rear Travel 300 mm (11.8 inches)
Wheelbase 1475 mm (58.1 inches)
Ground Clearance 375 mm (14.8 inches)
Wheels & Brakes
Front Tyre 90/90-21
Rear Tyre 120/90-18
Front Brakes Single disc. 1-piston calipers
Front Brake Ø 260 mm (10.2 inches)
Rear Brakes Single disc. 1-piston calipers
Rear Brake Ø 220 mm (8.7 inches)
Dimensions & Weight
Dry Weight 87.5 kg (192.9 pounds)
Power/Weight 0.4571 HP/kg
Seat Height 950 mm (37.4 inches) If adjustable, lowest setting.
Fuel Capacity 7.00 litres (1.85 US gallons)
Other
Starter Kick
Color Options Red/white
Notes

Spanish brand.

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Weight
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Brakes
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Suspension
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Transmission
Transmission and final drive affect maintenance, smoothness and everyday usability.
Rider Profile

Who Is This Bike For?

🟢
Beginner
A2 license compatible, manageable power.
🌲
Best For
Off-Road & Adventure
📏
Seat Height
95 cm / 37.4 in
⚖️
Handling
Very lightweight — easy to handle
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