LO206 Red Odenthal - Special Code Red Special - Performance Engine MountHOW TO CHOOSE YOUR CLAMP SIZE You need to know two things about your chassis: tube diameter and rail spacing type (I or K). Both are measured at the motor mount area on the driver's right side near the rear axle the section with two parallel tubes that hold the mount. Option 1 Tube Diameter Measure the outer diameter of one frame rail tube. Most karts use: 28mm common on cadet junior karts and some Birel AM29 30mm most common; Tony Kart, Kosmic,