Topic: 550F main jet...which way is up?

[Scott S]

 I found this question answered both ways using the search function.

 I'm chasing a rich condition on one carb. While going through that carb again (on the bike), I noticed that the O-ring on the jet is different than the position on the new Keyster jets I have. Is this main jet in upside down?
 Which way does the O-ring go? There's a shallow side and a deep side on the jet. One ring land is thin, one is thick.
 Which way is UP....toward the needle...and which is DOWN....towards the bowl?

[Scott S]

 Looking at an assortment of old jets that I have, and the "witness marks" on them from pliers or whatnot when being removed, the thin ring/shallow end goes UP.
 That would mean that this jet has been in upside down, right?

[flybox1]

These press-in jets are the same as on my 350f
the OLDER of the two picture jets has the o-ring in the wrong slot.

Keihin or Keyster? 

[Scott S]

 That's a genuine Keihin jet that has had the O-ring replaced. I'm hoping that's been the root of all my tuning issues. I installed a new O-ring and flipped it over.

[Duanob]

The stamp should be down and the o-ring should be up as if the carb were installed on the bike. The lower groove is for the leaf spring. If they are genuine keihins they sould have a size stamp and little logo visible on one end. I don't see a stamp on any of those.

[Scott S]

 The stamp is there on the old one. It just isn't clear in the pics.