stator winding coat melting temperature
This is a simple question that probably doesn't have a simple answer... How hot does a VN750 stator have to get to melt the "plasticoat" covering on the windings?
Motivation for the question... I've got an '06 VN750 that eats stators for breakfast, lunch, and dinner. MOSFET R/R, TPE stators (have eaten three in as many years), AGM battery in good condition and on a maintenance charger if the bike sits longer than two weeks without being ridden.
The stators are being cooked to death. The last one I removed left gray deposits all over the inside of the rotating magnet assembly, not to mention the rest of the engine: frequent oil and filter changes got most of the residue out of the engine, but frankly, I'm scared what I'll find if/when I finally resort to a complete teardown :-(. Engine temperature is normally no more than "center post" on the gauge, but hot Texas summers push the limits of what I've decided is a puny cooling system. Even with a 160-degree Honda automotive thermostat (per a recommendation I found elsewhere on this forum site), getting caught in slow-moving traffic pushes the temperature above center post, and the cooling fan can barely keep up with the heat load: temperature stabilizes about 1.5 needle widths above center post.
It's unacceptable to have to consider a stator to be a consumable item requiring annual replacement. The one currently in the bike is in the early stages of failure: measuring the AC voltages across the various combinations of A1, A2, and A3, I get 19 VAC at 900 rpm across every combination except one, which gives me a paltry 7 VAC. Discovered the impending failure by noticing the voltage across the battery dipping below 12V at idle, which doesn't happen when things are working right unless the radiator fan is running (in which case, I've seen the voltage drop to as low as 11.5V at idle).
At highway speeds, I've *never* seen the 14.5V across the battery that many of you insist is normal. I might occasionally see 14V, but 13.5V is more typical.
Any insight as to what's going on would be appreciated. Thanks in advance.