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hey guys
so I'm new to carbs and don't completely understand how to fix them. when i got my 50 it ran pretty good just wouldn't idle.its got a kamikaze 88 kit on it with the Keihin PC20 carb. i did some looking on the internet and it seemed pretty easy so i took it apart and cleaned everything. it has a 85 main jet 35 for the second jet. i put it all back together and with a few turns of what i believe is the fuel screw she idled again. when i pulled the coke up it would die. didn't bother me cause that would be the new way to kill the bike since i don't have a key. anyway when i took it for a ride it still rode good but when i would retract the throttle, the rpm would stay up for about two or three seconds. i thought it was the cable binding up or sticking so i took the cable out of the carb took the cable out of the sleeve and shot some wd up there, so with the throttle. put it back together and now it won't start unless the coke is on. seem logical with it cold but the idle is through the roof. i back the fuel and what i believe is the air screw all the way down tried again and does it still. when i put the choke down it dies. to me this seems like its getting too much fuel. i did some more looking on the internet and found an interaction chart for the carb. it says the main jet should should be a 92, and the factory was a 95. so is it the smaller the number the more fuel? while i was looking at my jet needle i noticed that the clip was on the 5th, very bottom, groove, so i moved it to the 3rd groove, same issue, then the first groove, and yet again same issue. bike just dies when i shut the choke off. when the coke is up and its running the idle is high and all the needles are still turned all the way in. oh yeah, even the i have the fuel valve closed at the bottom of the carb, gas is still racing out of the drain tube, another reason i believe its getting too much fuel. I'm at a loss and could really use some help. i don't know what to do from here. will probably take it to a shop but id like to learn and figure it out myself. thanks for the help guys, and merry christmas.
 

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The following baseline jetting is for the ShengWay carb (a Keihin PC20 clone), but it should get you running. The idle screw is in the center of the carb body, the air adjust screw is located near the rear opening where the air filter is.

The 20mm ShengWay carb is relatively easy to tune right out of the box. It comes with the #89 main and a #35 pilot jet, both of which you can buy the extra jets from TrailBikes or any TB sales rep. As a baseline setting, I use the #90 or #92 main jet, the #38 pilot jet, set the jet needle at the 3rd or 4th notch from the top, and the air screw at 1-1/2 to 1-3/4 turns OUT from seated. Make the necessary air screw adjustments IN to richen it a 1/4-turn at a time and see what the bike does. With some of the carbs, I've run it to within a 1/2-turn of being all the way IN to get rid of 98% of the off-idle hesitation. You might have to raise or lower the clip on the needle, depending upon your altitude, I'm at sea level.
 
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