Harley engine's can run about any oil, and don't need Jaso/wet clutch oil in them, because the transmission is seperate from the engine.
Inline 4 cylinder Japanese bike engines have an engine and transmission made together, and both share oil, and most all run wet-clutches(clutch submerged in the engine and transmission oil), so you need to make sure you have wet-clutch approved oil in the Busa engine, which viscosity and brand is up to you.
Non Jaso/wet clutch oil has friction modifiers to improve engine performance...but they will also make a wet-clutch slip.
Inline 4 cylinder Japanese bike engines have an engine and transmission made together, and both share oil, and most all run wet-clutches(clutch submerged in the engine and transmission oil), so you need to make sure you have wet-clutch approved oil in the Busa engine, which viscosity and brand is up to you.
Non Jaso/wet clutch oil has friction modifiers to improve engine performance...but they will also make a wet-clutch slip.