Actually there is no good logic to pair a spline with a clamping bolt. Consequence is that only the few spline faces next to the clamp will take all the load as the rest of the kickstart lever circumference cannot possibly move towards the clamping bolt with that spline. And we all know loads of stripped splines on kickers. I went for the bicycle type - or BMW - tapered bolt and milled flat on the kickstart shaft so hopefully this will be an end to the calamity. And yes, this is no quick mod to do requiring decent welding on the lever but then my levers were wrecked enough to decide for any alternative.
Vic