are K&N jets numbered different than factory jets?

[kilabeez0]

I know the jet kits require the adapter to fit, but I heard somewhere that the numbering system is different. Is this true?

I have a K&N filter with no lid, so I just ordered a 155 jet from the dealer. But I just won a K&N jet kit from ebay, so will the jet kit 155 be different from the factory jet 155?

[cals400ex]

the numbers are different. we do need to remember that a needle makes a difference on what size mainjet you may need too. i believe with the dynojet needle in place, the dynojets run a little bigger than the keihin jets. so the next size smaller than a 155 in the jet kit should work fine with the dynojet needle.