THE BEST BIG BORE STROKER FOR YOUR 250 PERIOD. FITS ALL'03-13 YAMAHA YZ250F MODELS! BIG TIME BOLT ON BIG BORE STROKER POWER! 13.5:1 CP PROJECT X forged piston.CP hi temp piston rings. Water pump bearing and seal. This is a bolt on kit with no machining required. Piston uses pump or race gas. Everything is new in the original packaging. If you have ANY issue with something you order from us PLEASE let us fix the problem before you leave feedback. We 100% guarantee we will find a reasonable solution to any problem. We want happy customers always. We recommend that this be installed by a qualified mechanic with experience doing this type of work. Piston comes with specific instructions for setting ring gap. If you do not follow these your motor will fail. The item "03-13 YZ250F YZ 250F Big Bore Stroker Motor Rebuild Complete Kit 300cc Hotcams" is in sale since Thursday, November 30, 2017. This item is in the category "eBay Motors\Parts & Accessories\Motorcycle Parts\Engines & Engine Parts\Big Bore & Top End Kits". The seller is "bpracingatv" and is located in Upland, California. This item can be shipped worldwide.