I have been using a G51 which I got used with little or no use. It is a made in Italy model so may be different. A few things I noticed is that it took forever to get broken in (ring), but once it did it ran real smooth and idled very low. Hossfly mentioned the carb restrictor. I didn't know that they ever had one, but it is probably a good idea. The ventury on this engine is much bigger than anything in it's class and even .60 size engines. I'm sure that is where problems with tuning come in. I believe the carb leaking is simply blowback out of the carb, which may possibly be remedied with a short piece of tubing on the carb to act as a velocity stack and keep the air going in one direction.

Rod S