I bought my first ATV(Coolster 3150DX2) back in February 2016 and built it with help. I also had help with emptying the "shipping oil" out and putting in a new bottle of 15w-40.
So I warmed up the engine a few minutes and took off the 17mm and drained the oil and noticed a spring and strainer flew out into the drip pan. I have NO idea on what order they go back in. I watched several videos about it, all of them said that I made a mistake. Supposedly their are two size bolts down there, 14mm and 17mm. The 14mm shouldn't be touched, but I don't see any other bolt that is down there.
Please help.
I will attach a couple pictures.

 

If this plug is at the lowest part of the engine seems that'd be the one. Old Hondas and Yamahas had this same setup. If the Coolster engine is a Honda type clone,then the screen should fit into the spring like these two.

 

Thank you. I ended up taking the wrong one out.
It was supposed to be the picture that I took "Was this the right one?" with white letters.
I took that one out and the rest of the oil came out. I also emptied the rest of the gas out and put some new gas in. Started it up and it started smoking but not through the exhaust. Hopefully it was just oil burning off the body that some oil spilled on.

 

Either way you have a clean oil screen also when you put it back in..On the old Hondas this was their only filter and drain but it did a good job..