The 2002 YZ450F is the top-drawer dirt bike in Yamaha's line-up , and it comes with a new 449cc engine, with liquid cooling and a 5-titanium-valve architecture, and redesigned automatic ...

Yamaha points to "the push for more environmentally ... There are two XEMX conversion kit versions for YZ250F and YZ450F dirt ...

XEMX makes two separate conversion kits (the air-cooled XE2 and liquid-cooled XE4) for Yamaha's YZ250F and YZ450F dirt bikes, but the brand is currently only accepting pre-orders for the XE4 model.

Yamaha shocked the dirt bike world in 2010 with the unveiling of its then-all-new YZ450F, which featured a reverse cylinder ...