Locus of stator failure

[msilverstein]

Upon examining my recently deceased stator I noticed that  the rear-most windings (nearest the shifter) were all burnt looking, while the rest appeared relatively fresh and happy.

This got me wondering if most stators fail in this same physical area. If true, then would it make sense to attempt to increase air flow over the rear of the stator cover in order to cool that area. Anyone have an idea of whether bolting a set of heat sink fins on the the rear of the stator cover would help? Perhaps even including a bit of metal to channel air flow through the fins? Would it even make a difference?

I could see drilling and tapping a few holes on to the rear of the cover in order attach a couple of electrical power supply heat sinks. It would be pretty easy to do, although it might make it look ugly.

[Dave T.]

I don't think the heat sink would help. If a specific area was burned, it may have been caused by not enough oil coverage in that area. The heat sink would just cool a SMALL area and would have to be mounted close to the flywheel bolt cover, since this is where the bolts for the stator thread into. I think keeping the oil level above the 1/2 way mark it the best bet, but the oil may be getting thrown away from the stator poles inside the flywheel due to centrifugal force.

Usually the magnet wire on the stator poles is rated for 155 degrees C, so if the oil temp is nearly 300 degrees, which it isn't (closer to 100 deg C) breakdown of the insulation is due to too much current in the wire (like a heating element) due to a short, bad R/R or just rubbing of the wire insulation due to vibration.

I am thinking of getting some 16 gauge wire to rewind my old core with to see how that would work. Stock seems very close to 18 gauge.

My 1.5 cents...   ;D