I recently did a rebuild on a conversion Ryobi 31cc. The carb that came on it was an 11mm Borg Warner carb that did not have a choke. The only carb I had available to replace it was a Walbro wt414 which is a 12mm carb. I also put an electronic ignition on it. When I tried to start it all I could get was for it to run for a few seconds then die. It seemed to be flooding out. Gas was dripping out of the back of the carb. This is with the choke off. I tried moving the sensor several times to advance the timing and I tried leaning out the carb untill they were almost closed. Same result. I finally concluded that either the carb was too big or something was wrong with it. I knew the engine ran with the other carb so I put it back on. Haven't had time to try it yet. Also, I know the ignition is good because I had it on another engine that ran fine. Mods I made to the engine was to put a Bowman ring on it and I opened up the back stop for the reed. Changed out the muffler to a gutted Ryobi muffler with a larger exhaust hole. The muffler had also been on another engine. What do yall think? Was the carb the problem? Also, after it would quit I would pull out the plug and it would be drowned in fuel. The engine is mounted inverted on a 4 star 120.

Thanks
Jim