If you are running a KT100 with the IKF/WKA required minimum 11cc in the combustion chamber and you are not worried about passing a tech inspection at a race then the best choice of gas is the lowest octane pump gas at your local service station.
Generally speaking, octane ratings are an indication of a fuel’s resistance to detonation and you’ll find that the higher octane blends need to be run very lean to perform well. If you ignore the conventional wisdom and try running the low octane gas you’ll discover that the engine will run clean and produce excellent power with a richer mixture that results in lower engine temps and longer component life. You’ll also discover that the engine is not as sensitive to the mixture settings and will run good under different weather conditions and with different drivers without as much attention to the needle settings.
It’s important to understand that the compression ratio mandated by the IKF/WKA rules is extremely low so there is virtually no chance of detonation unless the engine is run much too lean. Accordingly, there is no need for the expensive race gas with high octane ratings to protect the engine from detonation.
The KT100 is not a thoroughbred racing engine, it is an industrial engine adapted to karting with the emphasis on cheap, reliable and simple to run. It does need or benefit from expensive gas blends.
As for the oil… any of the oils mentioned above will work fine but I still prefer the castor based oils. I recommend Burris castor at 16 to 1. It is a very clean running castor and produces very little “carbon” buildup in the engines.