Years of experience on the race track have spurred us to create a special automatic speed change gear for racing. THE NEW MHR MULTIVAR DOES NOT REQUIRE TO DO ANY MODIFICATION REPLACING THE ORIGINAL ONE. TECHNICAL NOTES : the kit contains a 99.5 mm diameter mobile half pulley made of a special cast aluminium alloy. The contact surface between pulley and belt is super-finished with a diamond tool to guarantee a constant coefficient of friction, calculated to prevent both belt slip and premature wear. To satisfy the innumerable calibrations required by racing scooters, depending on track type and tuning of the motor, the kit contains 2 series of 6 rollers set and a counterspring in pre-hardened silicon-chrome steel alloy with counterclockwise (racing) winding. In addition, other springs of the same class with different loads are available as options. Suggestions for the setting The variator is supplied with two different roller sets: one of 3.9 gr. and one of 4.7 gr. in order to change the number of revolutions of the gear curve of your vehicle perfectly adjusting its speed and acceleration. Compatible with: - Aprilia: Area 51_S, Rally 50 AC_S, Rally 50 LC_S, Scarabeo 50 Min.AC_S, Sonic 50 AC_S, Sonic 50 LC_S, SR 50 Min.AC 94-_S, SR 50 Min.LC_S - Beta: Ark 50 AC_S, Ark 50 LC_S - Malaguti: Centro 50 AC_S, F10_S, F12 AC_S, F12 LC_S, F15 Firefox_S - Mbk: Booster 50 euro 0-1_S, Booster 50 euro 2_S, Mach G 50 AC_S, Mach G 50 LC_S, Nitro 50_S, Ovetto_S, Stunt 50 euro 0-1_S, Stunt 50 euro 2_S - Yamaha: AEROX 50_S, BW's 50 euro 0-1_S, BW's 50 euro 2_S