Built around Polini's minibike, sport motorcycle platform, the 2007 Polini 910 GP4 Air Junior utilizes a 39.7 cc (2.4 cu in) air-cooled single cylinder, two-stroke layout. In factory specification, peak output is rated at 4.2 HP (3.1 kW), transferring power to the rear wheel through chain final drive. Internal engine geometry specifies a bore and stroke of 36.0 x 39.0 mm (1.4 x 1.5 inches) with a 14.0:1 compression ratio.
On the scales, the 910 GP4 Air Junior measures 20.5 kg (45 lbs) dry. Rider ergonomics and chassis geometry center around a 395 mm (15.6 in) seat height — giving shorter riders and urban commuters confident flat-foot reach at traffic stops.
Standover Height
395 mm (15.6 in)
Engine
Displacement39.7 ccm (2.42 cubic inches)
Engine TypeSingle cylinder, two-stroke
Engine DetailsSingle cylinder, two-stroke
Power4.2 HP (3.1 kW))
Compression14.0:1
Bore x Stroke36.0 x 39.0 mm (1.4 x 1.5 inches)
Fuel SystemCarburettor. SHA 14-14
IgnitionElectronic with inductive discharge
CoolingAir
Transmission
Final DriveChain (final drive)
ClutchDry with centrifuge counter weights
Chassis
Frame TypeLatticed tubular frame
Wheels & Brakes
Front Tyre90/65-R6.5
Rear Tyre90/65-R6.5
Front BrakesSingle disc
Front Brake Ø148 mm (5.8 inches)
Rear BrakesSingle disc. 130
Dimensions & Weight
Dry Weight20.5 kg (45.2 pounds)
Power/Weight0.2049 HP/kg
Seat Height395 mm (15.6 inches) If adjustable, lowest setting.
Use this page to compare this motorcycle by its real specifications, not only by model name. Focus on the details that affect fit, comfort, handling, range and ownership.
Power
Compare engine output with similar motorcycles if acceleration, highway use or two-up riding matters.
Seat Height
Check the seat height against your inseam and riding posture before choosing a motorcycle.
Weight
Compare weight carefully because it affects low-speed handling, parking and confidence.
Brakes
Brake setup is worth comparing if you ride in traffic, mountains or with a passenger.
