If you've burned a valve, or have a sticky one, compression would be compromised.
The KACR compromises a conventional compression test; a leak-down test would identify a defective valve.
You have spark; you have fuel; don't know about the third component of the triad, compression (all three necessary for the engine to run).
Again, starting fluid insures a combustible mixture; if she'll run on starting fluid, but not on gasoline, a carburetor/fuel system problem is likely.
The intermittent nature of your problem compounds diagnosis and repair; a challenge perhaps even for a competent shop.
Sounds like you've done about all a shade-tree mechanic might in the field; seeking some professional help may be the next best logical step (I'm not unmindful of your remote location).
I might try a few long, brisk, powered tow-rope pulls, before I sought a camion para llevar el moto al proximo ciudad. (Truck to haul the motorcycle to the next city.)
Last edited by Damocles; 02-17-2011 at 10:38 AM.