Ya never know.
My Saito 125 died at the top of a loop and I thought it went lean and quit as I found the muffler pressure line split and off the tap. It was due, so given a fuel system overhaul but wouldn't start after completion, in fact not a single fire could be coaxed from it..
Timing ok.
Spark ok.
Valve train ok.
Compression ok.
Primed with methanol and still wouldn't fire, even spinning over with a starter. Hooked up a spare ignition, and it started on second flip.
This is the second RcExl ignition failure I've experienced in ten years and the first that would spark the plug out of engine but fail to fire the engine. The spark boot is a suspected problem having gotten oily.