Length of Time for an Engine to Cool Down

[hotrodjackson5700]

How long does it take for a scooter's air-cooled motor to cool down? I know you're supposed to wait to adjust the valves once the engine is cool, and was wondering if anyone has any ideas on the matter, to include ways of cooling it down quicker(yet safely). Any input would be greatly appreciated.

[scooterpimp]

Depends on how hot engine is? Couple hours should be fine. Aluminum cools rather quickly . Let it cool down naturally.