My 5239 mower surges or hunts during use. It starts on the first pull but acts as if it is starving for fuel. Adjusting the needle makes no difference as I can turn the needle until it hits the bottom of the engine and no change! I just rebuilt the carb so it is very clean. The surging is why I rebuilt the carb!
Should I open the main jet by drilling it to a larger diameter? If so, how much? If this is not the fix, what else should I consider? The fuel is 16-1 and is fresh. Could fuel with excessive oil cause this problem? It really produces a large amount of smoke!
Perhaps it is not a fuel problem. Perhaps the governor is sticking or is loose or...
The fact that the needle Has NO effect on how the engine runs has me stumped. It has always worked in the past. A needle and seat can not be a mystery, can it? Turn it in= less fuel. Turn it out = more fuel! In this case, the needle does not make any difference.
Yes, a too rich fuel mixture can be the problem. You might want to try the synthetic 2-cycle oils, which will change the mixture, but still keep the oils protection properties. I use Opti-2.
