Carb Jetting Questions

[pds00]

150cc howhit. Air box removed with a UNI filter, stock jets (114), stock muffler. Starts, idles and takes off good, then about half throttle it spitts and sputters and doesn't throttle up. Spark is white which tells me to jet up. The smalles one I had is a 134. that made it worse. So should I move to maybe a 120?
The one thing that is making me think twice is that it ran fine for about an hour with only a few minor backfires through the carb.

[beerbear]

i,am having the same problem. i have a k&n filter with 125 jet. it had 120 jet when a bought the kart and it was doing the same thing i have changed all wiring cdi,coil and resisiter and rebuild the carb did not solve the problem,

[BuggyMaster]

One thing you need to understand about these 150cc mini buggies as that none of them are created equal. In a Helix by American Sportworks, they come with a 114 main jet and a 34 pilot jet. right off the bat we put a minimum of a 128 main in to keep it from running too lean. the manufacturers are being forced to make them run lean to get them to pass emissions. However, in another brand, it came with a 108 main. I put a 112 in it and it started choking it out. Settled on a 110 for that one.

You are on the right track though. It takes a lot of experimenting to find the sweet spot. Typically, backfiring through the carb due to a jetting issue means you are running lean. If the 134 was too much for it, ya try the 120 and see what it does. No change, go to a 140 and see what it does.

All trial and error but don't give up, you'll find it eventually and become a master at changing the jets in the mean time.

Oh ya...it is VERY RARE that I have to change a pilot jet.

[beerbear]

i found my problem took a stock carb off my other 3206 which is all stock put it on and my problem went away so i copied the stock carb had to turn the air screw 1/2 turn now i'll watch the plug it make sure its not to lean we run at around 250=500 ft. i had to big of jet in the carb