I have never used it, but when I first started researching oil for OPE before I found BITOG I read several sites about go kart oils. There is a oil called Red-E. Look on Red-e.com/
Red-e has a history of providing winning performance in single cylinder 4 cycle racing engines. It is a straight 20 weight that holds up under the demanding temperatures and abuse a single cylinder 4 cycle air cooled brigs puts it thorough.
Users have said that in the demanding applications of go-cart racing many change oil after every race. With Red-e they are able to run it for several races, many run it for an entire day of racing. Red-e being liter than 30 does not load the engine down as much as a 30. And some post said that when they broke the engine down at the end of the summer the parts were still within original specks, though with all the stress on the metal you still should change the piston, wrist pin, and connecting rod.
Along with providing a lite load on the engine because it is a 20 instead of a 30, some posted that they also leave the sump a little low so there is less load on the engine, and even when the sump is low, Red-e holds up.
Check out Red-e.com and see if anyone around you carries it, but you probably will have to order it directly from the manufacturer.
From what I have read, if I were going to run a 4 cycle single cylinder go-kart and I really wanted to win, I would use Red-e.
Check out some of the forums on go-Kart racing. In some of those forums you can read about the success some people have had using Red-e in their 4 cycle go kart engines.
