The SH125i's engine is a compact, highly durable unit. It makes good power where scooter riders need it most, in the low to mid-range area and is quiet in operation. Revised PGM-FI mapping gives peak power of 9kW @ at 8,500rpm, with peak torque of 11.5Nm delivered @ 7,000rpm.
And its superb fuel efficiency of 47.4 km/l (WMTC mode) presents low running costs to the owner and a positive environmental message - further enhanced by its new EURO4 status. The allowable limits for exhaust tailpipe pollutants such as carbon monoxide, hyrdrocarbons and nitrous oxide specified by EURO4 are approximately half of those for EURO3.
A key fuel-saving technology incorporated into the SH125i is Idling Stop. It's operated via a switch on the right handlebar and, when enabled, automatically stops the engine running after three seconds at idle, and re-starts it instantly when the throttle grip is twisted.
It's seamless in use, thanks to a swing-back system that returns the crank to its position before air intake, and a decompression mechanism that negates cranking resistance due to compression. The ACG starter also generates electricity, doing away with a conventional system's motor and gears.
The 125cc four-stroke, liquid-cooled 2-valve engine is a masterpiece of mass centralisation. The radiator, rather than being mounted at the front of the machine has been built into the engine itself for a much simpler and lighter layout. Its core is highly efficient allowing the use of a smaller, lighter cooling fan.
A compact combustion chamber matches burn velocity and cooling performance, perfectly tailoring torque characteristics to suit urban riding conditions. Bore and stroke is set at 52.4 x 57.9mm, with compression ratio of 11.0:1. The air intake port is smooth, assisting gas flow and optimised ignition timing combines with the water jacket and radiator's efficient cooling to improve ‘knocking' resistance.
Low-friction technologies are employed internally; the cylinder sleeve uses minute splines on its outer surface to reduce oil consumption and improve cooling and the cylinder is offset, further reducing friction.
A shell-type needle bearing is used for the rocker arm shaft while smaller, lighter rollers work in conjunction with the cam profile and valve spring load. Rolling resistance within the transmission is reduced by the use of three main bearings, all designed to deal with the loads they each individually receive.
The SH125i's high-tensile steel tubular underbone frame is manufactured with both rigidity and durability in mind. Lightweight 16-inch aluminium die-cast wheels are key to its sure-footed handling ability and stability on a variety of road surfaces. New for 2017 they mount Michelin City Grip tubeless tyres. Wheelbase is a compact 1340mm, with rake and trail of 26°/85mm. Seat height is 799mm with a wet weight of 136.9kg and 180kg carrying capacity.
The rear shocks feature 5-step preload adjustment with 83mm axle travel. The 33mm telescopic front forks, with 89mm of travel, ensure excellent road holding and are tuned to give a compliant, yet controlled ride. ABS is fitted as standard; both front and rear discs have a 240mm diameter; the front caliper is a three-piston design, the rear a single piston.
Liquid-cooled 4-stroke SOHC single
Bore X Stroke
52.4 mm x 57.9 mm
Max Power Output
Fuel Tank Capacity
2034 mm x 740 mm x 1158 mm
Tyre Size Front
Tyre Size Rear
Brakes Type Front
Brakes Type Rear