Gain over 30hp with this kit and still be reliable! Key features: CNC Ported/Polished 4 valve head with race cam for maximum performance. 64mm bore with super thick 4mm cylinder sleeve. No risk of cracking and safe to bore out to 67mm if you want. 5 speed upgrades your stock 4speed to a 5speed like the new gen groms and will make your bike faster with the extra gear! Head can be installed with stock intake or koso 34mm intake. Kit includes the following parts. CNC ported/polished 4 Valve cylinder head. 64mm cylinder and custom 4 valve piston. 5 Speed Transmission kit. 1 oem cylinder base gaskets. 1 copper 64mm head gasket. This kit will not fit the stock crank case with out it being bored out. We offer this service as well. Recommend to be built by a professional. Cylinder head will come assembled with the valves and springs in the head. Piston will come with the rings installed and pre gapped ready for installation. Recommend using a adjustable cam timing sprocket to set the timing perfect by degreeing the camshaft. We will include a small guide for the build but it will not teach you how to build it. You will need a bigger injector and a aftermarket ecu for tuning. We recommend A-racer it is very good and super easy to use. If you have any questions please contact me.