ccm Nitro Xt down tube size?

GoldenMotor.com
could anyone tell me what size of bracket i need for this bike, it has a overly large "fat" down tube i measured with a tape measure but the website,sick bike parts.com recommends i use a caliper to get the right size of universal bracket, which i do not have and cannot obtain, the measurement i recorded is of the width from side to side of the tube, its roughly 1 7/8 " there is another site that has a "fat" down tube bracket also but has no size options- link-http://livefastmotors.com/Gas-Motorized-Bicycle-Motor-Mount-Fat-Frame-No-Drill-Motor-Mount.html, I'm afraid that if i order it, it will be too small like everything else i tried, PLEASE HELP I WANNA RIDE!:-||