Your engine has tightened and you wish 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 reassemble your YAMAHA YZF 450cc 4 stroke from 2003 to 2005 / YAMAHA WR-F 450cc 4 stroke from 2003 to 2006. 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 one so 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. However you will have a slight gain in power with this kit. Attached is the power curve so that you can see for yourself the difference between the original and the kit ATHENA. The assembly and adjustment instructions are also available below. 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.