Hi,
Did you have to make any other changes to the carbs for four stroke use or did yhey come with the engines? I have some 11mm versions off Toro trimmer engines that I would like to use with my Ryobi 4 cycle. I thought that a spring or something had to be added to the pump section. I read that you can also drill out the main jet to 0.015" (1/64th) for better performance. Their is in a Ryobi 4C thread on RCU with this info.

Dave