Hoca Secondary / Final Drive Gears for 50cc 4-Stroke 139QMB Scooters COMPATIBILITY: BMS – Apache 50 4T, Heritage 50 4T Diamo – Classic 50 4T Lance – Charming 50 4T, GTR 50 4T Roketa – Bahama 50 4T, Maui 50 4T, Sicily 50 4T Tank – Urban 50 4T, Sporty 50 4T, Viaggio 50 4T Many Other 50cc 139QMB Based Engines **This will not work on the QJ models Hoca gear sets in a variety of combinations for 50cc 4-stroke 139QMB engines. Choose from 16, 17 & 18 front tooth combinations and 41, 42 & 46 rear tooth combinations. **