It could be from too much or too little gas. You may have an air leak at the carb, check the gasket and the bolts. The carb could be flooding. Do you smell gas? Will the engine run a bit with gas poured through the carb? If it's a new engine maybe the valves were not set correctly. It's a good idea to always check as the china factory quality control isn't known for quality control. Someone else will chime in with more help I'm certain.
Hi. Thankyou for the advice on the spark plug. This book on small engines says, "A sparkplug that fires outside of the engine may not function when the voltage requirement doubles under compression". I've also read to make sure and replace the gasoline because it has a short shelf life of six months to thirty days. Would it be safe after that to spray starter fluid into the air filter then pull the starter cord? Thanks again.
Is your plug wet? Also loading up a motor with starting fluid especially either is not a good idea. Use it to diagnose your symptom. You don't need but a tiny snort of it to make the motor fire up.
You can also put a teaspoon of gas into the cylinder when replacing the plug and if it was missing fuel from the equation it will fire up once.
Your book is totally right about the spark needing to be hot to get into a compressed cylinder. In some cases like with a cracked plug you will see a nice spark outside the cylinder but not know whats going on when it is installed. Also if the spark circuit is breaking down bad cdi or wire any connections this thing can happen.
For now lets just keep it simple. Is your plug getting wet? How long has this motor been in storage? Yes gas goes bad with age sitting in storage. A carb can get all gummed up to where the venturi jets inside etc will plug up.