Here is the big bore kit proposed by ATHENA to increase the displacement of your motocross / enduro YAMAHA YZ 125cc 2 stroke from 1997 to 2004. This kit in Ø58mm against Ø55mm of origin thus makes it possible to pass your motor bike of 125cc has 144cc real! A gain of torque and performance will be immediately felt. It allows a gain of 3 HP on average which is huge on this vehicle. You go from 37.5hp to 42.0hp thanks to the high ATHENA BIG BORE. Enough to have fun on the tracks or in the forest. ATHENA has moreover well planned things because this top engine is sold complete. It includes the cylinder, piston, ring, cylinder head and all the gaskets you need for a quality and tight reassembly. The advantage of taking this engine is that it is designed to be mounted on the original connecting rod, so you have no modification to do! Attached is the power curve so that you can see for yourself the difference between the original and the big bore. You will also find a detailed list of vehicles on which this cylinder can be mounted.

Fits on:

YAMAHA YZ 125 1997

YAMAHA YZ 125 1998

YAMAHA YZ 125 1999

YAMAHA YZ 125 2000

YAMAHA YZ 125 2001

YAMAHA YZ 125 2002

YAMAHA YZ 125 2003

YAMAHA YZ 125 2004