Modern Vespa

I'm in the process of cleaning out the cooling system of my recently acquired 1986 Honda Helix. The fluid hasn't been changed in many years and it shows with plenty of rust. Can anyone recommend a good coolant system flush that's safe for aluminum radiators? I've been flushing out the system with just distilled water and I'd like to finish it off with a good flush before installing the new coolant. Thanks!

For a real nasty cooling system, I use Simple Green. Dilute it, fill up your system, and ride the scooter for a while. If you can remove the thermostat and put the housing back on, with no t-stat you can flush the whole system both ways with a garden hose. Then I run distilled water through the system, reinstall the thermostat and fill with Peak concretated coolant.
Find your cooling system capacity, and fill 1/2 that amount with full strength coolant. Top it off with distilled water. After you bleed the system, top of with 50/50 strength. https://simplegreen.com/cleaning-tips/automotive/radiator/
This is tank out of a 15 year old Morphous from Arizona with original coolant.

Thank you! Will do it this weekend. Already ordered the gallon of Simple Green HD Pro. Thanks again!