Part #765 has a double taper. As you tighten the screw, #766, it pulls the cams together, which grip the inside of the handle bars. I asked Wayne the same question, as his kit doesn't come with #770 either. He said the part was not needed as he makes the parts out of a heavier gauge than the originals. I wonder if simplex did that also in the latter years. Of the three bikes I have, none still had the original twist throttle on them. They aware all missing, and two of them were replace by a half-assed pull brake throttle. The only thing I did to the one from Wayne was run a sanding scroll inside part #762, this made the action much smoother, and fit better over the new handlebars.
Rick
