another idea...how bout if YOU warm up the kx125, get it cleaned out, then turn it over to the wife. Turn the choke off right away, then 1 minute of idling is PLENTY, then gently ride the bike, as the engine comes up to temp, find the powerband and hold it wide open for a bit in 3rd gear or so. This is how these bikes were designed to run! If the pilot circuit/air screw are proper, as well as the jet needle clip position, once the bike is cleaned out as I describe above it should be fine for the rest of the day on a plug.
50:1 will tend to wear out parts prematurely, I suggest 32:1!