Pocket dirtbikes have bigger 10" rims/tires and the gearbox operates at 7:1..Gearing should add another 4-5:1 for a total offroad gearing of 11-12:1......With cag rims/tires you can run a 17tooth on the countershaft easily.....Most cags/gprsr's with stock gearing operate at 10.8:1 or 9.5:1 depending if its 6/68 or 7/68 gearingprobly dust from the bobchop build. i worked most of saturday getting frame straight and figuring stuff out.
have you mounted a dirt bike gearbox on a cag? ifso whats needed for final drive regarding gear size/tooth size on output side. also whats the offset from the case to the drive sprocket?