Way too much heat!

[Si Coe]

Well after the problems with my LRP Sphere / LRP X11 7.5 combo it was suggested I try another motor, so I acquired a Novak 4.5R. Now I know its a 'hot' motor, but I didn't expect what happened.
First test run (D4, stock spur, 18 pinion on tarmac) it ran for about 3 minutes, before one of the battery leads came desoldered. It had near totally drained a 4300 Lipo in that time, and the Deans connector had melted!

So thinking I'd got the gearing wildly wrong, I switched to the smallest pinion I own, a 15, soldered on a new deans plug, put a different pack in and tried again. This time I managed about 30 seconds before a wire came unsoldered. The Deans connector had melted again.

By now I'm getting concerned, so after replacing connectors (again) I tried gently revving the car on its stand. As you nail the throttle you can feel the wires getting warmer. Even off the ground, the heat is immense. However the drivetrain itself rolls nice and freely.

All the wires involved are 14awg Novak, the connectors proper Deans. The ESC gets hot, but doesn't thermal. The motor is very warm, but not scorching.

I assume something is badly wrong here, but what bit is at fault?