Other Klx110 won’t start

I have a 2005 drz110 It is the same thing as the older klx110s
So I recently rebuilt the whole entire bottom and left the original piston and rings and cam chain in the engine. I rebuilt the carburetor cleaned it out. I got everything running Crisp And I had 2.7 hours on it on the bottom end rebuild and now my bike will not start. I took my head off to see if I had a bent valve but there fine and I adjusted them to spec and put everything back together and still won’t start. The bike has compression and is getting spark. Does anyone know what the problem could be?
Before anything , replace plug .. cheapest fastest ... Then , Start at the flywheel key , make sure it is intact . Then check valve timing , then compression . Then ignition for spark and timing ... has to be something simple .. It's Not that hard ....