Prototype 5 – Ducati Based

Engine Type

Air-cooled opposed-piston rotary- & reed-valve 90° V-twin

Bore x stroke

86 x 57 lower, 60 x 25 upper

Capacity

616cc intake, 575cc compression corrected, 643cc expansion corrected, 592cc exhaust.
616cc intake, 756cc compression, 732cc expansion, 592 cc exhaust
Measurements taken with upper crankshaft 20° retarded
Corrected measurements taken after ports are closed.

Compression ratio

10.6 : 1 (approx)

Fueling

4 x 35mm Mikuni CV carburettors

Ignition

Dual ignition, Ducati CDI & two H-D 12 volt coils

Power

40 bhp at the rear wheel at 5000rpm as tested after Sir Alan Cathcart’s test ride. (Computer predicts 86bhp @9000rpm, 41 ft/lb @ 6000rpm)

Valve timing

Intake open 20° BBDC 520° close 60° ABDC 240°

Duration 440° (this is not a mistake)
Maximum port area at 20° ATDC
Exhaust open 40° BBDC 500° close 60° ATDC 60°
Duration 280°
Maximum port area at TDC 0°
Overlap 260° (also not a mistake)
The reed valves control the beginning of intake according to engine demand.

Transmission

Clutch: wet multiplate
Gearbox: 5-speed
Final drive: 520 chain

Frame

Garden gate style 1″ square tube space frame

Suspension

41mm FZR Yamaha forks, 50 x 25 RHS steel swing arm, twin Koni dampers

Brakes

Front: twin Ø 300mm floating discs with 4-piston calipers
Rear: single Ø 220mm disc with opposed piston caliper

Tyres

Front 120/70 VR17, Rear 160/60 VR17

Wheelbase

1400mm

Rake/Trail

98mm/23°

Weight

153kg dry