pilot jet issues....

[jerryfaxman]

I bought a 2008 Hisun GY200 a few months back. It had no spark so a new CDI corrected the issue. Here's the issue that stumps Me. To make the bike idle at all I have to unscrew the air mixture screw out about 5-6 turns. Out of frustration I ordered a new PZ30 carb on e-bay and it looked identical. The original carb is marked K F pride of Japan and the new one is a Keinen PZ30. Other than that they are identical in every respect. The new carb also does the same thing...I must turn the idle/air mixture screw out about 5-6 turns. I've checked manifold mount and double verified there is no vacuum leaks. It is very responsive when You throttle on it and I'm certain it's not a main jet problem. It will not idle or run at all with the idle/air mixture screw out 1 1/2 or 2 turns. My son informs Me that by turning the idle/air mixture clockwise it makes the idle circuit run "richer" by restricting the air flow and allowing more fuel to the idle circuit. So therefore by unscrewing the air/idle screw it tells Me that the Pilot jet is to large, and by unscrewing the air/idle screw Your allowing more air into the idle circuit. His suggestion is to reduce the size of the pilot jet. It is not an issue with valve adjustment. When the bike idles it doesn't have that "thump..thump..thump idle. It will idle and "pop" occasionally through exhaust almost like a mis-fire. I'm baffled and any suggestions would be appreciated. So far the only advice is to reduce the pilot jet to a 25 size. I live in Minnesota and this bike only has 238 miles on it. Please Help Me cause I hate to order another carb! The question I have is should I go smaller or larger on the pilot jet? I want that smooth Thump..Thump..Thump idle. Also checked that choke was functioning and it does open all the way with choke off....