still having trouble w the idle.ive checked the valves there fine,cleaned the carb and all air pass.and jets.its a dellorto phm 40mm i went up a size and down a size on the pilot.it ran or idled a little better but after 15-20 seconds it would die.and thats only if the mix screw is turned in almost all the way about a1/4 turn from bottom and idle screw about the same,almst all the way in.i went from a 48 to a 45 pilot thats when it would idle for a few seconds and at start up would backfire thruogh carb.it has no problem starting when cold or hot and i noticed that even with the mix screw turned in so far,when i hit the throttle i would get black smoke,not alot but enough to see it.also its running a 175 main jet not sure bout choke.if someone could point me in the right direction i would really appreciate it. thanks