My buddy just replaced his stator with a used one. Ran good for 200km. On another trip made 30 km, died towed it to town. Started again seemed to run fine, so he tried it again. Made it about 20km dead. Got it home, fired up again.
Am I safe to assume this stator is no good?

I would agree with the stator. They work fine then when they heat up wont work again. I have seen it before

I had exactly the same problem with my sled. We tried a stator but it wasn't the problem. There was a bare wire under the motor that would short out on the motor when it warmed up, let it cool and the sled would run great for 15 minutes then die. We made it do that probably 20 times while we tried to find the problem, finally pulled the motor and found the bad wire. Haven't had a problem since then, that was 5 years ago. Any way, don't expect the expensive stuff until you've check some of the cheap stuff. I've read dozens of posts going on and on about bad stators on Mach's, we have 2 of them and never had a stator problem.