The pitch is 26 threads per inch, but the diameter is a little more tricky. I measure a nominal of 1.712" diameter, which is quite a bit undersize for 1-3/16", even considering thread toping. Unfortunately it does not work out to anything else either, Imperial or Metric. My pitch diameter micrometer only goes up to one inch, and I do not have thread wires for that fine a pitch, so I am not able to measure a precise pitch diameter. In any event, you would be advised to remove you carburetor and have the ring nut(s) threaded to suit, or used comparatively to turn up a threaded mandrel to use as a gage.
-Doug
