Moped

Overview

A moped of this type is a small-displacement, step-through scooter with an automatic transmission. A single-cylinder four-stroke engine, typically 50 to 125 cc, drives the rear wheel through a continuously variable transmission, so there is no manual gear shifting or clutch lever. The step-through frame and underseat storage make it a practical commuter, and its low weight and modest power keep it within the lightest motorcycle licensing categories in many countries.

How it works

Power begins in the Power Unit. Inside it the Engine Core runs a conventional four-stroke cycle: a carburetor meters the air-fuel charge, a piston compresses it, a spark plug ignites it, and the valve train times intake and exhaust. Spent gas leaves through the Exhaust System, whose muffler and catalyst silence the engine and reduce emissions.

Engine output feeds the CVT Transmission. A variator on the crankshaft uses centrifugal roller weights to change the effective pulley diameter with engine speed; a V-belt links it to a spring-loaded driven pulley, giving a seamless, stepless ratio. A centrifugal clutch couples drive only above idle, so the machine creeps away smoothly from a stop without rider input.

The engine and transmission hang from a unit-swing Rear Suspension that doubles as the rear wheel carrier, sprung by a single shock, while a telescopic Front Fork handles the front. The drivetrain, fuel, and rider sit on the Frame & Bodywork, a steel underbone chassis clad in plastic panels with a flat floorboard.

Fuel is held in the Fuel Tank and rider controls live on the Handlebar Assembly, including the twist throttle and brake levers. The Electrical System supplies 12 V power, CDI ignition spark, and lighting from a flywheel magneto. Hydraulic disc braking up front and a drum at the rear bring the moped to a stop.