First Look: 2010 Yamaha Yz450f

FIRST LOOK: 2010 YAMAHA YZ450F

Is Backward Better?

Yamaha may be the last of the Japanese Fab-Four to come to market with a fuel injected 450cc motocross bike, but its new YZ45OF joins the party with a few extra sur prises. First, the engine features a rearward-slanted cylinder for improved mass centralization and straighter intake and exhaust systems. But the cylinder head's swapped intake and exhaust posi tions draw the most attention. A lightweight airbox and 44mm Keihin throttle body `~reside in front of the engine to feed the new batteryless fuel-injection, while the exhaust header exits to a longer silencer from the rear of the head. Other changes include a new pent `roof combustion chamber with four titanium valves, a higher 12.5:1 compression ratio and new shorter-stroke cylinder dimensions (97.0 x 60.8mm).Pricing was not available at presstime.

Blake Conner