I'm new to this site and hoping to get some help. I'm working on a Joyner 250 atv (jn250da) and having problems with a rich condition.It has an electric choke and I cannot find any wiring diagrams on it. I have AC voltage at the yellow wire going to the choke and the green wire grounded.There is also a coolant temp sensor in the loom but leads to nowhere.If I remove the choke coil and run the engine while there is power on the choke I don't get any change. The choke has a spring loaded needle (that looks like controls the fuel)and a spring loaded sleeve (that looks like it controls the air bleed).Any ideas would be appreciated.

Is this a new atv or used? You can play with the air screw on the side of the carb. To lean it out you need to screw it in a bit. This is something you can look at.

It is about 4 years old. the only adjustment screw is an air bleed that enters right before the throttle plate and it makes no change. This atv fires up cold runs and accelerates good for about 30-45 seconds then starts to idle rough and no accel.

Is it a manual choke or auto?

Automatic electric choke.

Sounds like the choke is doing its job. Almost like the problem starts when the choke shuts off. You can drop your metering rod down a notch or 2 that will lean it out if that is your problem. I would start there. Make sure your air filter is clean.