YSR50 Hi-Performance Kits Carb Size Part Number 20mm (Carb/Manifold Kit) 001-537 22mm (Carb/Manifold Kit) 001-538 The kit has tested up to 60 m.p.h top speed, is tractable throughout total RPM range, and has excellent acceleration! Kit Includes:     *20mm or 22mm custom jetted VM Carburetor     *R-1100 K&N air filter (Order Number: 005-105)     *SM-55 manifold adapter with cable (Order Number: 005-066)