This is the updated Mugen Ninja JX-21 B01A engine with the lightened cooling head and 7mm carb insert. Engine mofdifications include EB Mod JX-21 V2 head button and lightened connecting rod. The motor is then re-assembled and broke in using 30% nitro fuel. Finally the motor is tested on the EB Mods X-dyno to ensure maximum performance. Please refer to the attached dyno graph to see before and after performance gains just from the EB Mod JX21 V2 head button alone. We'll get updated graphs of the motor with the lightened rod modification. Engines are shipped via USPS Priority Mail with Signature Confirmation and insurance. Please note that when Ed breaks in the engine and runs it on the X-dyno he uses his own O.S. carburetor and EB Mods fuel. After the motor has been ran, Ed reinstalls the inspected stock JX-21 carburetor (that has not seen any fuel), cleans and oils up the engine. The carburetor is still at the "rich" factory settings and will need to be tuned for your pipe, header and fuel combination as well as for your environment (outside temperature, humidity and altitude). INTERNATIONAL customers please email for shipping quote.