I picked up a quart of 33% Nitro fuel sold by Traxxas called "Top Fuel". It cost $14. It is made by PowerMaster. I'll mix it with some gasoline and see what happens. It says not to use it for aircraft but I asked the hobby shop owner why and he said because it doesn't contain enough oil. That is perfect for what I am doing since the B&S 4-stroke has a wet sump and is better off without any additional oil. Stay tuned.