The engine/transmission unit is a water-cooled 52° V-twin, fitted parallel with the frame. The engine has three valves per cylinder, two for the intake and one for the exhaust, operated by a single overhead camshaft via rocker arms. The camshafts are chain driven off the crankshaft.
The engine/transmission unit is constructed in aluminium alloy and the crankcase is divided vertically. The crankcase incorporates a wet sump, pressure fed lubrication system, and houses a chain driven oil pump. The one-piece forged crankshaft runs in two main bearings. The left-hand end of the crankshaft carries the alternator rotor. On XL600V and XL650V models the ignition timing rotor is on the right-hand end of the crankshaft. On XRV750 models the ignition timing triggers are incorporated in the alternator rotor.
The clutch is of the wet multi-plate type and is gear driven off the crankshaft. The transmission is of the five-speed constant mesh type. Final drive to the rear wheel is via a chain and sprockets.