[What direction to go?]

All this is my first post... What direction to go?
While my wife was on her annual girls camp trip this last weekend our 2015 CFMoto ZForce 800EX buggy with ~700 miles had some issues. (it is home now) Without me being around to diagnose or perceive the problems I am going off what she and other girls described. First she noted a louder than usual clattering between the seats around the valves, lifters and Chain Tensioner area. Then a power lose felt in the accelerator. She turned around and headed back to camp. eventually the Buggy stalled . It would turn over but never would start. At camp they checked the oil and determined it was around a quart low. Scary! FYI. Oil, oil filter were changed along with cleaning the air filter at 550 miles.... They opened the filter box and seen oil on the smaller case breather side. And noted the (stock) air filter was dirty as well. (from the feeds on the forum I will be changing out that stock air filter right away... Grrrr  didn't know about this substandard POS!). They topped of the oil, cleaned the air filter as best as they could. The next morning our buggy started right up and she took it for a test spin. Within 20 min. it stalled again. And wouldn't restart. She then parked it for the rest of the weekend. When at home it started up and back it out of the toy hauler. Hmmm... Now it sets in the garage. I am worried that the top end might be toast. Not being real keen with this buggy. I don't want to do any further harm by starting it up and testing it. What would be a good place to start looking for the stalling issue and related oil loss. Ultimately it will need to be taken to the Dealer To isolate what is going on with the clattering heads. Please any direction would be greatly appreciated. 
Wild Wade O                 

[2015 Z Force 800 53/Trail EPS]

Well, you are taking it to the dealer. That's the place to start. Lets hope there is something left to work with. The stock filter has taken the top ends out in less then 800 miles before..that's why we are so on to people to change them out before even their first ride. Let's see what the dealer says.