You may find the choke and throttle cables don’t fit your quad very well and so they are out of adjustment especially the carbOK. Thanks for your help. I'll give that a go. :grinSounds like you have a carb issue. I'd ditch the ebay carb and put an OEM carb on it. I would bet dollars to doughnuts that fixes your problem.
I took aftermarket carb off mine to find a knot tied in throttle cable—choke wasn’t even closing