Originally Posted by
davidl
Measure inductance to determine the number of wire turns on the stator. The 13.5 and 17.5 ROAR approved motors should have a minimum inductance number associated with the approval of the specific motor. Those meters are around $275.
These numbers aren't listed publicly. I think that is the true problem with using any kind of meter to detect the number of winds a motor has.
Here's the description Roar gives for a 17.5:
8.5.4.3.1
ROAR Stock motor: Only three slot “Y” wound stators are permitted. No delta wound
or slot less stators are allowed. Only circular (round) pure copper magnet wire
permitted. The three slotted stator must be wound with 17.5 turns of 2 strands of a
maximum diameter of .813 mm per slot. The resistance for each slot of
the stator shall be tested and a minimum resistance figure will be determined upon
submittal.
The real problem for tracks inspecting motors is that the minimum resistance figure they determine upon submittal, isn't a public number.