These are the known mechanical and performance specifications for your 2015 Derbi GPR 125.
Basic Specs

Engine
Displacement124.76 ccm (7.61 cubic inches)
Type
DetailsSingle cylinder, four-stroke
Max RPM
Compression12.0:1
Bore/Stroke58.0 x 47.0 mm (2.3 x 1.9 inches)
Valves/Cylinder4
FuelingCarburettor. 30 mm
IgnitionCDI
Exhaust
LubricationMechanical oil pump
CoolingLiquid
Fuel Economy & Polution
Fuel Consumption
Fuel Capacity14.00 litres (3.70 gallons)
Emissions
Chassis
Frame Type
Rake
Trail
Front Suspension40 mm upside-down fork.
Front Travel110 mm (4.3 inches)
Rear SuspensionMonoshock.
Rear Travel120 mm (4.7 inches)
Seat
Seat Height800 mm (31.5 inches) If adjustable, lowest setting.
Alt. Seat Height
Total Height
Total Length1,977 mm (77.8 inches)
Total Width795 mm (31.3 inches)
Ground Clearance
Wheelbase1,355 mm (53.3 inches)
Dry Weight120.0 kg (264.6 pounds)
Wet Weight137.0 kg (302.0 pounds)
Wheels & Brakes
Front Tire/Tyre110/80-17
Rear Tire/Tyre130/70-17
Front BrakesSingle disc. Radial caliper
Front Brake Diameter300 mm (11.8 inches)
Rear BrakesExpanding brake (drum brake). Floating caliper
Rear Brake Diameter218 mm (8.6 inches)
Wheels
Comments
Spanish brand.