Bore and stroke    55.0 x 42.0 mm, 2.17 x 1.65 in.
Displacement       399 cu. cm, 24.3 cu in.
Compression ratio  11.5:1
Valve train        Gear driven DOHC, 4 valves per cylinder
Intake valve       opens at 1 mm lift 5 deg ATDC
Intake valve       closes at 1 mm lift 33 deg ABDC
Exhaust valve      opens at 1 mm lift 33 deg BBDC, 38 deg BBDC (California)
Exhaust valve      closes at 1 mm lift 5 deg BTDC, 10 deg BTDC (California)
Lubrication system Forced pressure and wet sump
Cooling system     Liquid cooling system with cooling fan
Air filtration     Paper filter
Crankshaft type    Unit-type, 6 main journals
Engine weight(dry) 57 kg, 126 lbs.
Firing order       1-2-4-3.
Cylinder arrangement   Vertical 30 deg. in line four