Do u want to switch it plug´n´play or is the engine not built in yet? If it´s not built in you can lighten your flywheel as well. But choose a good "engine builder" because the have to be rebalanced correct. There are lightened flywheels on ebay as well. I got one in my VR and it works great. But it was not built together correctly. Had to take off the sprocket and set it on in another direction. Price for them on ebay is about 150 €. I´ve got best experiences with a new weight of about 4,0 to 5,5 kg. I apologize for my english mistakes. :-)
