hi i have a 1991 kdx 200 i recently picked up from my dads house. it used to run fine but since ive gotten it back it hasnt ran right. it smokes like a @#%$ and doesnt idle. i installed a brand new carb with no effect, tried all different kinds of jets to no avail, cleaned the pipe and silencer and changed the plug. nothing seems to make it run any better. it has no response to air/fuel mix screw adjustments or idle screw adjustments. the only thing i did with some noticeable change was i took off the choke completely(which created a massive vacuum leak) and it ran a lot better... i have hit a troubleshooting brick wall and NEED HELP!