Start with some sort of oil designed for wet clutches. Increase the viscostiy with other oil types (bigger numbers, more viscus) if you want the clutches to engage later.
smaller numbers will give you more revs. bigger numbers will protect metal parts better.
synthetic oils will take longer to break down.
the keyword here it OIL and make sure there's enough (the side fill hole is the minimum required) check it often, especially once the automatic chain+wheel oiler starts working.
get one of those $50 expansion exhausts, a few larger Main jets (5-10 bigger), and drill some holes in the airbox for +5 MPH. Or dont (edited)