The Polini Hi-Speed variator kit offers a combination of improved accelaration and a slight increase in top speed. Well engineered and good quality kit with 2 sets of variator weights (16x13 at 3.6g and 4.9g) and 1 x set of stronger clutch springs. If you want more low-down pull and top speed is not too crucial, this is the one for you. Suitable for: APRILIA Area 51 98-02 ZD4MY Gulliver 50 AC 96-98 ZD4LH02 Gulliver 50 LC 97-99 ZD4LHA Rally 50 AC 96-04 ZD4MD0 Rally 50 LC 97-98 ZD4MDB SR 50 AC 94-96 (Minarelli Engine) ZD4MR SR 50 LC 94-96 (Minarelli Engine) ZD4LC SR 50 LC 97-99 (Minarelli Engine) ZD4MZ SR 50 Netscaper LC 97-98 (Minarelli Engine) ZD4MZ SR 50 Stealth LC 97-98 (Minarelli Engine) ZD4MR SR 50 WWW AC 00-02 (Minarelli Engine) ZD4LY SR 50 WWW AC 97-00 (Minarelli Engine) ZD4LY Scarabeo 50 2T AC 93-97 (Minarelli Engine) 072 / 081 / 081P1 / 092 / 094 Scarabeo 50 2T AC 97-06 (Minarelli Engine) ZD4PF Sonic 50 AC 98-07 (Minarelli Engine) ZD4PBB0 Sonic 50 LC BENELLI 491 GT 50 AC (-03) (Minarelli Engine) 491 RR 50 (-03) (Minarelli Engine) 491 RR Replica 50 (-03) (Minarelli Engine) 491 ST 50 (-03) (Minarelli Engine) 491 Sport 50 (-03) (Minarelli Engine) K2 50 AC (-03) (Minarelli Engine) K2 50 LC (-03) (Minarelli Engine) Naked 50 AC (-03) (Minarelli Engine) Pepe 50 (-03) (Minarelli Engine) ITALJET Dragster 50 (Minarelli Engine) KTM Ark 50 AC Ark 50 LC Chrono 50 Quadra 50 Tempo 50 MBK Mach G 50 AC 02- SA22 Mach G 50 LC 02- SA22 Nitro 50 -98 55BR Nitro 50 03-12 SA14 Nitro 50 99-02 55BR Nitro 50 Naked 05-12 4B0 Nitro 50 Naked 13- 1PL Nitro R 50 2T 13- 1PH Ovetto 50 2T YAMAHA Aerox 50 -98 5BR Aerox 50 03-12 SA14 Aerox 50 99-02 5BR Aerox Naked 50 2T 13- SA424 Aerox R 50 2T 13-14 SA421-00 Aerox R 50 2T 14- SA421-01 Axis 50 3UG/5AK Breeze 50 4RC Jog 50 92-01 4SC, 3SA Jog 50 R AC 02-12 SA22 Jog 50 R AC 13- SA486 Jog 50 RR LC 02-17 SA22 Neos 50 2T 02-03 SA151 Neos 50 2T 04-07 SA211 Neos 50 2T 08-12 SA34 Neos 50 2T 13- SA451 Neos 50 2T 97-01 5AD Neos Easy 50 2T 13- SA457 Why 50 02-03 SA03B Why 50 04-13 SA03E Why 50 99-01 SA036 Zest 50 93-99 4FW