brand new z160ho you say..
is this brand new never started?
some of these engines are prone to breaking the kick starter gears, don't stress tho you can get replacements from dhz or more than likely where ever you purchased the engine from.
just dont try and keep kicking it as you run the risk of cracking the R/H side engine case..
im not saying that the above is the problem but my suggestion to to take the engine or bike back and get the seller to suss it out, some places will void the warranty if you go digging around pulling the engine apart.
the above problem can be caused from a bad carb tune or poor kick starter action which tends to make the engine kick back and jam under your foot. ie; not enough engine speed during kick starting