Address:Hoppers Crossing Hoppers Crossing 359 Old Geelong Rd
The already renowned, powerful 449cc, liquid-cooled 4-stroke SOHC engine has had major modifications for 2013. Increased punch out of corners, with finer throttle control and feel for rear wheel traction were key goals for Honda’s engineers.
Optimizing the four-valve Unicam engine’s efficiency for these aims started with improved gas flow rate through the cylinder head; refined inlet port shapes provide 3% more flow, and revised valve timing, with more overlap, maintains maximum power at high rpm, while increasing low and mid-range output.
Bore and stroke remains 96mm x 62.1mm, but the exhaust valves have increased in diameter – up 1mm to 31mm – for a 3% increase in flow. The compression ratio has also been raised, from 12.0:1 to 12.5:1. The result is an engine that delivers more torque low down, with a linear torque curve plus stronger mid-range power and no loss at the top-end.
The five-speed close-ratio gearbox is brand new, and has been strengthened with every bearing and gear improved to deal with the engine’s extra torque.
A new airbox and filter element ensure efficient filtration in the dustiest of conditions, and maintain a consistent internal pressure when the throttle is opened hard.
The long, narrow inlet trumpet also increases air flow rate for smooth throttle progression at low to mid-rpm. The PGM-FI fuel injection has been revised to suit the engine’s improved efficiency, with fuelling and ignition maps that maintain power output even in deep, soft