Usually starts first or second pull, generally runs smooth and throttles up well (although occasional "cough" or backfire), but sometimes stalls (either at speed or idle) and then won't start again for 20-30 minutes. Same restart problems when I shut it down manually.<br /><br />Just replaced head gasket and spark plugs and I'm running fresh gas. Fuel bulb is full and tank is venting properly, so I'm assuming a carb problem. Tried fiddling with (what the shop manual calls) the "pilot" screw near the top of the carb on the side with limited success, i.e. after small adjustments the motor would restart after shut-down two or three times, but then problem returns. Also tweaked idle screw, but I don't think idle is the problem, since it also stalls at throttle or while accelerating.<br /><br />Anybody have these symptoms and can tell me what specifically might be causing the problem (i.e. jets/float/other)? If cleaning doesn't help, is a carb rebuild kit for this engine expensive? If I'm going to have to rebuild carb anyway, would it be much more expensive to convert to 15 HP?<br /><br />Any assistance much appreciated.
