Dude.... You go to the Yamaha dealer and ask him to look up what it came with.
Then you pay for and order THAT jet (because they prob won't have it in stock).
While you are there... ask him what other sizes are offered for it by Yamaha.
If you were thinking of ordering a Puch or Tomos jet... it isn't going to work.
Got to go to aYamaha dealer.