From MopedWiki

This is a small but growing list of scooter and moped cylinder stud spacings, in order to provide you with hackability and kit craziness.

This can be measured as the diagonal, from top left stud to bottom right stud, or vice versa.

• Minarelli AM6 (RS50) - 73mm
• Tomos - 62mm
• Puch E50 / ZA50 - 62mm
• Puch Cobra GTL - 66mm
• Honda Hobbit PA50 - 70.5mm
• Minarelli Horizontal - 71mm
• Derbi revolution start 5 - 65mm
• Peugeot Buxy SV-GEO - 67mm