A: The numbering sequence on these belts are the size. The 835-20-30 belt has a Length: 835mm (32.87"), Width: 20mm (0.78") and a Angle: 30 degrees. The 743-20-30 belt has a Length: 743mm, Top Width: 20mm, Groove Angle: 30°. Compare that to what is currently on the kart. One question though is if your kart is a TrailMaster Mid XRS-R, this is not a 150cc kart. It has a 6.5 HP engine with a torque converter and may use a
669-18-30 belt
Answer provided by: BMI Karts (4/22/2016)