This used to be a simple question to answer, but there are now many different coolant-additive chemistries available, and they're not all compatible. (For example, Volkswagen G12 is a very good long-life coolant formulation, but G12 + conventional green coolant = nasty brown sludge that clogs up the system ... they must not ever be mixed ...)
If you just want to top up the system, the standard coolant in your bike is compatible with conventional aluminum-compatible coolant, the cheap green stuff. It is not compatible with certain types of extended-life coolants, normally red, pink, blue, or purple. That doesn't necessarily mean you can't use those coolants - but if you do, you should flush the system completely so that the various coolant chemistries don't mix, and then stick with what you've switched to.