I don't know any Iranian Jew in Israel by the name of Sabourjian, therefore it can't be a very common Jewish name. Sabourjian means Street sweeper. Ahmadinejad's grandfather was indeed a street sweeper, and maybe the family tried to move up the social ladder by changing its name.
Suspected assailant in car-ramming attack in West Bank shot (Haaretz)
from the article: Is Ahmadinejad trying to hide his Jewish roots by bashing Israel?