Emilios,
It's a brain teaser that probably has an obvious solution, but you insist spark is good, you are getting fuel and you have normal compression. Adding a few more possibilities, now for fun:
1. On your 40 mile trip, did you run low on gas and, maybe, suck in water that was there from a previous fillup or other event?
2. Did you refill on gas from an unknown and, maybe, questionable source?
3. Is your float stuck one way or the other?
4. Is your fuel filter in the carburetor clear.
5. Was your check of the spark recent enough to know it is not the mag condensor gone bad from the heat on your long ride? Maybe this hangs the spark only when trying to recharge faster than when you kick it.
6. Is your fiber magneto gear stripped of a few teeth?
7.
8.....
200.
If, somehow, one of these is the reason, I'll faint. Then I'll get up and stick my chest way out and strut around with plumage fully deployed. No, really, I'll claim it was dumb luck and that only through the exhaustive advice of our other members do I know anything at all, which would be mostly true.
Richard L.