I've got a Ryobi 4 stroke that's in the process of being converted ( just started the conversion). First thing I'd do is give the stock carb a fling in the trash can and put on a two needle Walbro. The one I'm using is a W 1123. It came off by IDC 31cc 2 stroke weed eater and it bolts right up to the manifold. I had to richen up the needle settings from what the weedeater had, but other than that it ran fine. And yes it'll pull fuel with the stock pulse port on the manifold. I haven't run it on a test stand with a prop as I am in the process of figuring out how I need to mount the engine. As a FYI, I first used this carb on a Briggs & Stratton 34cc 4 stroke and it turns a APC 18x6W prop in the high 8000 rpm range on a test stand. I did remove the stock muffler and am running a straight pipe ( sounds too cool ! ) to get that kind of rpm. Also please note that I'm at 3500' MSL which may attribute to the higher rpm. Good Luck on your conversion.

Greg