Your engine has tightened and you want to start again on a quality engine so you don't have to disassemble it soon ? Then here is the complete engine top proposed by ATHENA to rebuild your YAMAHA WR-F 450cc 4 strokes from 2007 to 2015 / YAMAHA YZ-F 450cc 4 strokes from 2006 to 2009. This kit is sold complete as on the picture with its axle, clips, ring, piston, gasket and its cylinder. This kit is not a big bore, it has the same characteristics as the original it is Ø95mm which gives us 450cc. This kit will allow you to refurbish your machine and especially to have a quality cylinder as reliable as the original. You will still have a gain of power of 0.5hp or a total of 54.5hp by putting the kit ATHENA compare to the original engine which is 54hp. Attached is the power curve so you can see for yourself the difference between the original and the kit ATHENA. It is of course of excellent quality as usual at ATHENA. The nikasil is really of excellent manufacture to guarantee you an increased reliability. We also have all the gaskets, rings and all the spare piston dimensions so that you can keep your cylinder as long as possible. Below you will find a list of vehicles compatible with this kit.