I bought this 110cc Roketa ATV for my son on his B'Day last year in July. Bought it from a Weekend market from the dealer. The ATV has been consistently giving starting trouble though (almost from the beginning). I try to start it, get the spark,..and eventually the battery goes dead. I recharge the battery, try again & the same thing happens. I went ahead & changed the battery suspecting that the old one probably not charging enough to start the engine, but that also was of no help. I don't have much of technical background, but I also figured that the Engine Oil was dirty, so I drained that out & replaced it with fresh oil (I have no clue if dirty oil had anything at all to do with starting the engine, but I thought that the dirty oil as it is won't be doing any good to the ATV). Frustrated I approached the dealer but (as quite expected) was denied any help. Actually got into an argument with him.
With my limited technical expertise, I'm really struggling to get get the ATV back in running condition. Any advise will be highly appreciated. Am also looking for any regular servicing guidance/maintenance tips to get the most out of the ATV. Any ideas...

 

Before when it was hard to start (but did eventually did start up), did it run OK? When the engine was warm did it start up right away? If so I would do a valve adjustment. This is a very common cause of hard to start quads (and it is something you need to do periodically).

You say you have spark. I just want to be sure: Did you check spark by pulling out the plug and holding the plug threads against the engine while cranking the starter motor?

Also try this: After cranking the starter for a while, quickly pull out the plug and check to see if it is wet with fuel. If it is dry, pour in a half teaspoon full of gas in to the cylinder and quickly reinstall the plug. Crank the engine and see if it sputters at all.