The liquid-cooled, 4-stroke SOHC, 155 cc, 4-valve, fuel-injected engine with VVA in the Aerox 155 gives out a maximum horse power of 11.0kW(15.0PS)/8000r/min and a maximum torque of 13.9N.m (1.4kgf.m) /6500r/min. The bore x stroke delivers excellent power and torque characteristics. The cylinder head along with a compact combustion chamber achieves a higher compression ratio that boosts combustion efficiency. It also optimizes the coolant pathway to improve reliability.

The engine adopts a Variable Valve Actuation (VVA) system that contributes to linear acceleration characteristics and a pleasant feeling when accelerating. It works via a mechanism that shifts between two intake cam lobes, one for the low rev range and one for the mid- to high rev range, with 6,000 rpm as the shifting point. This complements the torque curve for excellent torque throughout the rev range.

The Smart Motor Generator eliminates the sound of meshing gears, achieving a silent start every time. When starting the engine, the Starter Generator Assembly turns the crankshaft directly without having to drive it through gears, thus eliminating the sound of the meshing gears for quieter starts.

When the vehicle is idling, the Automatic Stop & Start System automatically stops the engine thereby saving fuel. The rider can easily re-start the engine by simply twisting the throttle. Also, the SGCU (Starter Generator Control Unit) monitors running conditions and inhibits unnecessary frequent engine starts and stops in conditions such as congested traffic.