ENGINE TYPE

SINGLE CYLINDER 4-STROKE

VALVE AND CAMSHAFT

DOUBLE OVERHEAD CAMSHAFT OPERATING 4 VALVES

BORE AND STROKE

100 MM BORE X 83 MM STROKE

DISPLACEMENT

651.9 CC

COMPRESION RATIO

9.7 TO 1

POWER OUTPUT

34.5 KW (46 BHP) AT 6500 RPM

TORQUE

57 NM (42 FT/LBS) AT 5000 RPM

TRANSMISSION

5 SPEED

SEAT HEIGHT

730 MM (29 INCHES)

FUEL TANK

14.2 LITRES (RESERVE 1.5 LITRES) STANDARD UNLEADED

BRAKES

FRONT 320 MM DISC - REAR 220 MM DISC

DRY WEIGHT

180 KG (396 LBS)

MAXIMUM SPEED

95 MPH

ENGINE TYPE

SINGLE CYLINDER 4-STROKE

VALVE AND CAMSHAFT

DOUBLE OVERHEAD CAMSHAFT OPERATING 4 VALVES

BORE AND STROKE

100 MM BORE X 83 MM STROKE

DISPLACEMENT

651.9 CC

COMPRESION RATIO

9.7 TO 1

POWER OUTPUT

34.5 KW (46 BHP) AT 6500 RPM

TORQUE

57 NM (42 FT/LBS) AT 5000 RPM

TRANSMISSION

5 SPEED

SEAT HEIGHT

800 MM (31 INCHES)

FUEL TANK

14.2 LITRES (RESERVE 1.5 LITRES) STANDARD UNLEADED

BRAKES

FRONT 320 MM DISC - REAR 220 MM DISC

DRY WEIGHT

190 KG (396 LBS)

MAXIMUM SPEED

100 MPH

WHY FOUR VALVES ARE BETTER THAN TWO

The valves let the air and fuel mixture in and out of the combustion chamber where it is burnt and turned into power. Larger valves will let more air and fuel in and out allowing an engine to produce more power than one with smaller valves, but it is not possible to keep enlarging the valves as power demand increases. Above a certain size the valves get too heavy to open and close quickly enough. More importantly, very large valves work well at high engine speeds when the air flow is fast, but they work less well at low and mid range engine speeds when the air flow becomes too slow to keep the fuel completely vaporised for complete, efficient combustion. Designers of modern high efficiency engines now favour four smaller, lighter valves per cylinder with good air flow to achieve high power output at high engine speeds whislt retaining excellent air flow and more torque at lower engine speeds. On the road, this gives the rider an engine capable of producing both strong top end power and easily controllable low speed torque, making the bike responsive over a much wider rev range.

WHY HAVE WATER COOLING?

Air cooled engines are much simpler and cheaper to build, but they work over a much greater heat range from a cold start on a cold day, to nearly overheating when producing maximum power on a hot day. Water cooling along with thermostatic control produces a much smaller heat range. The various engine components expand and contract as the engine temperature varies. Designers have to allow large tolerances and clearances in air cooled engines to overcome this. A water cooled engine can be built to much finer tolerances and is therefore quieter, and capable of producing more power than an air cooled engine from the same amount of fuel.

WHY HAVE TWO SPARK PLUGS FOR ONE PISTON?

When the fuel in an engine ignites it burns rapidly, producing power. The burn process starts at the spark plug and ends near the edge of the piston. Any fuel that is not burnt in this incredibly short time is wasted and leaves the engine as pollution. By starting the burn at the same time but from two different spark plugs, more of the fuel is burnt and converted into power. There is less wasted fuel and therefore less pollution, and more power than a single plug from the same amount of fuel.