Re: new motorized bike
Welcome to the forum and congratulations on your first build.
I'd wait until you get two or three hundred miles on the engine before worrying about performance modifications. It usually takes that long to break an engine in properly and to see how it will run in the stock configuration.
Typically a tuned exhaust (expansion chamber) will give you the most bang for your buck. The 36T sprocket will help too. But get it broken in first and only make one change at a time instead of several at once.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"