They are the 5mm, same jet size as the 250 bikes take. That racing planet price is really good, I couldn't even mail them that cheap lol. I'll vouch for then though, been good dealings lately. The carb does not have gaskets anywhere all orings that only need replacement of it sits with gas. If everything else is stock a #86 jet works well, 500" and normally 65 degrees here. Also have a look at my exhaust derestrction post, worth doing.