Hi everyone, thanks for looking.

So I picked up a second hand coolster 125cc atv, and it was running alright during the demo. When I brought it home I decided to change the oil (guy said he hadn't done it in a while). I pulled out the wrong screw first and had to put the spring back in. When I went to start it up it kept trying to turn over, and when I gave it gas it kept making a very loud popping sound and there was a burning smell as well. Any ideas as to what it might be?

Where I'm at: Gas tank full, fuel line checks out, battery charged, spark plug fine, following proper starting procedure every time.

Thanks for any advice!

 

alright, I'm an IDIOT hahaha. turned the fuel mix screw about a quarter turn and she fired right up. Still puzzled as to why that is though?

 

check your valve clearance.

 

Glad to hear you got it going.. turning the fuel screw out let more gas in.. more gas got it going.. try another 1/4 turn.. you can go as far out as 2 1/2 turns (1/4 turn at a time) and see if it runs better.. after 2 1/2 turns a larger pilot jet is needed.