Featured: Honda’s new 755cc parallel-twin

Unicam cylinder head

The unveiling of a brand new Honda engine is always a special moment. Honda promises exciting peak power, as well as plenty of torque in the low-to-mid range.

The 755 cc twin-cylinder with eight-valve Unicam cylinder head delivers 67.5 kW (91.9 hp) at 9,500 rpm and 75 Nm of torque at 7,250 rpm. The bore and stroke are 87 x 63.5 mm with a compression ratio of 11.0:1.

In the
Honda CB750 Hornet
the new twin cylinder provides a ride weight of 190 kg and a power-to-weight ratio of 0.36 kW per kg / 2.81 kg per kW.

Compact and lightweight

The compact and lightweight (and a configuration used by the MX competition-ready CRF450R) Unicam head operates the 35.5 mm intake valves via cam and the 29 mm exhaust via rocker arms. The intake elevator is 9.3 mm and for the exhaust Honda specifies 8.2 mm.

For crisp pickup and throttle response, patented Vortex Flow Ducts provide a more uniform distribution of side scoops to the airbox, which then feeds downdraft intakes and 46 mm diameter throttle bodies.

270° crankshaft

The 270° crankshaft and uneven firing order create a characterful two-cylinder feel. To wrap the motor as tightly as possible, there is no balancer drive sprocket; the primary drive sprocket doubles the duties and also rotates the balancer shaft.

The water pump is tucked away in the left crankcase cover and no water-cooled oil cooler is needed. The cylinders also use a Ni-SiC (Nickel-Silicon Carbide) coating, as also used in the CBR1000RR-R Fireblade and CRF450R.

Assist/slipper clutch

An assist/slipper clutch – with angled disc segments – provides a light lever feel, simplifies shifting and prevents rear wheel bounce during hard braking and quick downshifts.

Thanks to software, the new twin cylinder is also available in 35 kW A2 version. Engine power will then be a maximum of 48 hp (35 kW).