Radically revamped Yamaha crossers

YAMAHA can be credited with starting the modern era of four-stroke motocrossers and it’s taking its 2014 machines to another level with almost entirely new bikes in both the 250cc and 450cc categories.

While the YZ450F carries over last year’s engine, including its signature reverse-raked cylinder, the rest of the bike is almost all new. The chassis is “250 class dimensioned” according to Yamaha’s blurb, and uses a hydroformed aluminium beam design with no fewer than ten different types of forged, cast and extruded aluminium parts. Even the engine is tweaked, with a new ECU and gear ratios.

If the 450 is largely new, the 250 is an entirely new bike. As you can see from the pictures, it’s now almost indistinguishable from the 450, sharing the same basic engine and frame design. It’s the first time the 250 has gained the reverse-rake cylinder concept, and while it shares some parts with the 450 motor it gets a completely new cylinder head, piston, ports and valve mechanisms and even the crankcase is lighter than the bigger bike’s. Its chassis is identical to the new 450’s frame, with the same combination of aluminium parts.

Both bikes also get an angular new approach to their styling and share identical bodywork and suspension, contributing to the fact that despite the capacity difference the two machines cost almost the same amount; that’ll be £6399 for the YZ250F and just another £1 per cc to upgrade to the YZ450F at £6599.