Okay so not really for the US market Gyro models but it can be made to work. Apparently it was made for the older Honda Lead (1st Gen Aero) AF01 bikes.
47mm Malossi bumps the cc up to 70. Pretty standard cast iron kit.
Comes with cylinder, piston, rings, pin/clips, new reeds that may or may not fit your bike, and a gasket kit.
Malossi 316170