Manco Magnum 606 Sprocket

[houndsden]

I have a Manco Magnum 606 with a Robin engine. After it is ridden for a few minutes the sprocket will move and of course the chain will come off. I tighten the allen screw with a ratchet but it will still move after a few minutes. I can loosen it up and align it and tighten back up but after a minutes it will move again. Anybody got any suggestions. The only thing I can think of is buying a new sprocket hub but I really didn't want to if I didn't have to or if it might not work.
Any insight will be very helpful

[metalstudman1]

Welcome-Is the sprocket carrier damaged? If so then replacing it would be best. But if it's simply the carrier sliding around then buying a couple of locking collars should resolve the issue. Also if the set screw isn't holding it from spinning, if there is keyway on that part of the axle then tighten it there, or get it lined back up and remove the set screw- then with a drill bit(smaller than the set screw) drill a small indentation in the axle where the set screw seats in it to keep it secured in one spot.

[houndsden]

Thanks for the reply - I thought about the locking collars but couldn't find any that would work so I tried two radiator clamps which just moved with the sprocket. I am going to try drilling an indentation for the set screw. Worse case it sheers the set screw and I replace the sprocket hub.

Thanks again