I boosted this Yamaha YZ250F up to a YZ290F with a 6mm big bore kit from Athena!! Monster torque doesn’t even come close to describing the dirt slingin, wheel standin, crazy power this little giant puts down now!! Third gear wheelies with just the flick of a wrist!!

I still recall the first time I met a Genesis motor back in the 90’s. Those five valve configurations really blew me away! The general idea is less mass with equal or more flow equals higher revving and performing engines! Four stroke design and technology has increased at an amazing rate in the last several years. The intense amount of horsepower while maintaining calm, controllable power from 2000 RPM’s and up has made these bikes more fun, frantic and fierce all at the same time. I love my job!!

Athena makes a quality product!

The old piston in the new big bore cylinder.

Shiny and beautiful!!

2007 YZ250F

5 is better than 2.