Just read a copy of SportRider's "Ask the Geek" , by Andrew Trevitt. Regarding Aluminium radiator care, and aluminium engine care with liquid cooled engines. With confirmation from coolant supplier Royal Purple, they confirmed distilled water should be avoided at all costs when renewing coolant in your bikes. Use of distilled water can be described as a holdover from the days of brass/copper radiators.
Among other negative effects, It seems because distilled/de-mineralized water is vacant of all mineral content, it is in fact "hungry" for mineral content, and will chemically attack the internal grids of radiators, with leaks and unrepairable radiators. OEM recommendations for 50%-50% distilled water/antifreeze typically is enough to stop corrosion from the inside. Just the same, Royal Purple recommends using filtered tap water or tap water that is not too hard [water rich in minerals, like from a farm well], but to avoid waters from a home water softening system [salts] and not sea water from a desalination source [Saudi Arabia]. The say inexpensive drinking water is best. Maximum 4 year lifespan between changes.
The other corrosion issue involves electrical contamination from 'stray voltage' if the radiator is not grounded properly. The cooling system should be checked with a multimeter between the coolant fluid and other hard parts of the bike. No more than 300 millivolts [.3v] should register.
Perhaps the race track guys out there can confirm this, but I assume it's still racetrack prep to use non antifreeze coolant, straight water in race bikes on the track to avoid slippery race surface during a race. Would be interesting to note how many guys racing use distilled water thinking it's the safest for the internals of the engine and radiators? I know I've taken notice of this news with my one liquid cooled bike, with it's 2 $1000 each radiators!!!