Okay, so I’ve posted here before about this ATV, it’s been having a wiring issue that’s fixed now. But I have a couple different problems which I suspect are all related to the carb but I can’t say for sure so I’ll describe them and y’all tell me what you think

it has an extremely weird idle, when the choke is all the way up (open I think?) it runs high, so high that it’ll drive itself kinda like a car when in drive, if I put it in neutral like this the motor will max out RPMs and stay accelerated like I’m pushing the throttle but I’m not. When I have the choke at the halfway point it’ll run without the weird acceleration problems but will die if I’m not constantly revving it. I got it from my dad who said he had changed the carb but hadn’t started the ATV after he did so. I’ve tried adjusting the idle screw with no luck on that front

 

He probably put on a larger carb. and now the throttle cable is too short causing it to idle high. Could also have a gasket leak on intake.

 

Something else I thought of too, I had noticed when he put the carb on he didn’t run the fuel lines through the shutoff valve, and is the air filter supposed to face the front of the ATV or the rear? This one is facing rear but every video I’ve seen they all seem to be facing frontward

 

Those shut off valves always seem to leak after a while, so he probably just bypassed it. I've seen air filters both ways. Most are rear facing. I wouldn't think it would make a huge difference either way.