KCCRAIG, welcome back! First let me tell you I have zero experience with 4 stroke gassers other than watching a few run and reading about them on the various forums. If you are looking at the Saito radials, I would highly suggest you scan the various Saito radial threads here on RCU. Those engines can be good power but they are not without their problems .... especially for their cost. Regarding the Saito single cylinder gas engines, a good friend had one that ran quite well but it constantly stuck the exhaust valve from time to time. They just don't seem to get enough lube to the rocker area and the hot running exhaust valve builds up carbon on the valve stem causing it to stick. Mechanical cleaning returns the engine to normal again until the next time. With so many excellent 2 stroke gas engines on the market, unless you just have to have the 4 stroke sound, I'd go the 2 stroke route but that is just me. The gas radials certainly excel in the sound department.