Hello, My name is mason and i recently purchased a coleman bt200x mini bike

I purchased a mikuni (chikuni) 22mm carburator kit with filter for it and i cant seem to get it tuned correctly......

i have not touched the needle nor have i replaced any jets. I am currently using the stock jets in it and the stock needle setting.

the bike is backfiring really bad. It also doesnt want to idle correctly.... then i noticed i had alot of fuel in my oil.

I am not very knowledgable on carburators... at all....

i currently live in missouri where the elevation is around 460 feet above sea level.

The modification i have already made to the bike are as follows

Governer removed
Torque converter
header and muffler pipe.

i have seen alot of success to these but i cant seem to get it right....

if someone could please help me with my issues i would greatly appreciate it. I am new to all of this as well.