I just got done rebuilding an old B&S 18 HP opposed twin. Many thanks to the help I received on this board! It starts up fine, idles smooth, throttles up and sounds great until you take the choke off, then it falls on its face. I have adjusted the governor and am pretty confident I have it correct. Fresh gas and filter of coarse and I have checked for intake leaks and cleaned the carb. I adjusted the mixture screw and it will run at low RPMs without choke but not 1/2 - full throttle without choke. I did check the fuel shut off solenoid and it is getting voltage and the plunger moves easily to the touch but when I had the carb apart I hooked the wire to it and grounded the side to the mower frame and cranked the engine over but could not tell that the plunger moved at all. Any ideas on what I'm missing??