Smoother Torque at Any Range, Greater Controllability.
398cm3, fuel injected, single-cylinder four-valve DOHC
The thoroughly revised engine still retains the same proven level of performance that makes the DR-Z4S so compelling. A great number of engine components have been changed to comply with the Euro 5+ emissions standards, OBD II requirements, as well as the latest regulations pertaining to noise.
Fuel Injection
The change from a carburettor to a fuel injection system makes the engine more tenacious and controllable when riding at low speeds on rough surfaces or twisty forest trails.
Dual Spark Plugs, New Piston Design
The DR-Z4S/SM utilizes two iridium spark plugs, which feature heightened spark strength, within the engine’s single cylinder. The result is improved combustion efficiency at low rpm and smoother power delivery.
New Cam Profiles
The profiles of both the intake and exhaust cams have been optimized so the engine delivers improved low-speed torque, tenacious staying power at low rpm, and a satisfying punch to output at high rpm.
High-Performance Intake and Exhaust Valves
Two lightweight titanium intake valves and a pair of hollow sodium-filled exhaust valves contribute to maximizing combustion efficiency and performance. By reducing weight, they allow greater freedom in designing cam profiles optimized for both power output and emissions.