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'IT WORKS LIKE THIS': Senior engine manager Tsutomu Ishii talks about the Honda VFR1200F's V4 engine
After weeks of hype and carefully-managed "leaks" Honda has released full details of the 2010 VFR1200F sports-tourer and its 1237cc, V4 engine that uses a combination of existing technology from other Honda bikes and 'Why didn't I think of that?' ideas to make it remarkably compact and provide a smooth, linear power flow.
Instead of having the four cylinders in a symmetrical V, the two rear cylinders are as close together as if they were in a parallel twin - which makes the engine as narrow as possible between the rider's knees - while the front cylinders are slightly further apart.
The cylinder head design is borrowed from Honda's CRF motocross bikes and uses a single overhead camshaft to operate the inlet valves directly and the exhaust valves via rockers.
Another CRF trick is the use of a vent pump to scavenge crankcase pressure to the airbox. It's never before been used on a road bike, says Honda, but the effect is the same as on the motocrossers - instant response to the fly-by-wire throttle and improved fuel consumption.
Honda claims 127kW at 10 000rpm and 129Nm at 8750rpm, on a kerb weight of 267kg.
The VFR1200F will be available at launch in South Africa late in the first quarter of 2010 with a six-speed manual gearbox and shaft drive. Honda SA says the high-tech, dual-clutch semi-automatic version will be released here in the third quarter.
Even the manual transmission is unusual, however, in that its output shaft is in front of the countershaft rather than behind it to make the engine cases more compact without resorting to a vertically stacked layout, which typically has a notchy gearshift.
A slipper clutch prevents the rear wheel from locking under engine braking and the universal joint of the shaft drive is offset to prevent the climbing under acceleration - and squatting when the throttle is suddenly closed! - that has always characterised shaft-drive bikes.
The compact engine allows a long, single-sided swing-arm within a short wheelbase for optimum handling, with a conventional Pro-link rear monoshock rear suspension, and adjustable 43mm forks modulating wheel movement.
SIT IN THE BIKE, NOT ON IT
Six-piston brake callipers clamp down on 320mm discs in front and a 276mm disc at the rear, linked by Honda's notoriously complex yet effective combined braking system and the electronic anti-lock brakes that were introduced on the CBR600 and CBR1000RR for 2009.
The frame and fuel tank have been kept as narrow as possible in the middle and seat height reduced (thanks to the compact cylinder heads and narrower rear V of the engine) so the rider sits "in" the bike rather than on it for improved control and feedback - and the side benefit that it's easier for riders with shorter legs to reach the ground.
The VFR1200F's layered fairing positively vents hot air away from the rider and improves high-speed stability, says Honda, while channelling cool, dense, slightly pressurised air into the airbox for more efficient combustion.
The headlight is the same as that of the CBR1000RR but uses total internal reflection to illuminate a "light bar" on either side, forming a lit X on the front of the fairing.
The VFR1200F will be available in metallic red, silver or pearl white; prices will be announced at the time of launch.
SPECIFICATIONS
ENGINE
Cylinders:
Four.
Capacity:
1237cc.
Bore x stroke:
81 x 60mm.
Compression ratio:
12.0:1.
Valvegear:
SOHC with four overhead valves per cylinder.
Power:
127kW at 10 000rpm.
Torque:
129Nm at 8750rpm.
Induction:
PGM-FI electronic fuel-injection with four throttle bodies.
Ignition:
Computer-controlled digital transistorised with electronic advance.
Starting:
Electric.
TRANSMISSION
Clutch:
Hydraulically-actuated multiplate wet slipper clutch.
Transmission:
Six-speed constant-mesh gearbox with final drive by offset shaft.
SUSPENSION
Front:
43mm inverted cartridge forks adjustable for preload.
Rear:
Pro-link rising-rate linkage with remote-reservoir gas-filled monoshock adjustable for preload and rebound damping.
BRAKES
Front:
Dual 320mm discs with Nissin six-pot opposed-piston callipers.
Rear:
276mm disc with Nissin twin-piston floating callipers.
TYRES
Front:
120/70 - 17 tubeless.
Rear:
190/55 - 17 tubeless.
DIMENSIONS/WEIGHT
Wheelbase:
1545mm.
Seat height:
815mm.
Kerb weight:
267kg.
FUEL TANK
18.5 litres.
MANUFACTURER SUPPORT
Two years unlimited distance warranty.
SERVICE INTERVALS
20 000km.