Borrowed my quad to nephew rode it in first gear for like four blocks started to leak oil into air box once he shut machine off I tried to turn it back on but it won't start what can it be

 

Clean the oil up from the box,install a new filter if needed,check that the plug hasn't fouled and check the oil level. Plus this is a high maintenance machine just like the Outlaw. Valves have to be check and oil and filter changed every 15 hrs!!