I've got a 2007 Katerra KMV250 ATV. It's similar to the baja wd250u.

I have cleaned the carb, adjusted the needle inside the carb to lower the clip to make it more rich (doesn't solve the problem.)
I followed the one thread https://atvconnection.com/forums/3-g...ut-carb-2.html but it is still poping at high idle although cleaning the carb now allows it to run fine at low idle without any choke. The idle adjustment screw is out 3 1/2 turns however it does not seems to make any difference.

questions:
1. Any suggestions?
2. Can anyone tell me where this connection is supposed to goto in the pic?

 

No where it’s sort like a vacuum line but it just hangs out.
as for the bogging and popping sounds like cdi, spark coil issue.
I remember going through this on my sons 110 (I know it’s smaller but concept has to be the same air, fuel, spark). I adjusted the carburetor for weeks even bought a new one. I had an extra plug, coil, and cdi box (6 pin adjustable) it got it to idle fine but when you snapped the throttle it popped like crazy or tried to ride it bogged like not enough gas. I cleaned the plug and noticed the spark plug wire was not even really connected to the boot. Swapped coil and plug but still had same issue so I swapped the cdi box just because I had and that did it.
my 2 cents anyway