Hi Michael, what wattage are the motors? the MY1020 is normally fitted with a 25h sprocket (although can be found with a timing belt pulley) which has a 'D' central hole to suit the shaft. The threaded size of the shaft is normally M8. I would suggest a rubber coupling (CV) between the motor and the wheel. This will help with vibration / shock and any misalignment. Details of these motors can be easily found on the web, just type in the motor ID (MY1020) and go to images, some will have dimensional details for you.
Hope this helps.