Why wont my honda 400ex turn on?

Question

My atv has spark, the carburator is working, and the valves aint stuck. I was riding it and all of a sudden it turned off and it has turned on since.

Answer 1

Have you checked your oil at all?

Because most ATVs have an oil level/pressure interlock that prevents it from starting.

Answer 2

assuming it has good spark and is getting fuel then you have to have a mechanical problem.

low compression

timing chain jumped time

bent valve

sheered flywheel key

i would double check the basics like gas in the tank, clogged fuel vent, oil, and get a new spark plug. you could have had a spec of dirt in the carb and clogged one of the jets.