What is the greatest number of pages (daf) you can go in the Babylonian Talmud without encountering Abayei or Rava? I've heard it was 3?
Rava appears on Nedarim 55 (then falsely on 56 in the word "Maarava") and not again until Nedarim 62.
Abayei appears on Nedarim 56 and not again until Nedarim 63.
So there's a stretch of 5 daf containing neither Abayei nor Rava. This appears to be the longest such stretch in the Babylonian Talmud.
HOWEVER, Nedarim has the least text per page. A different metric would be the number of words between appearances of Abayei or Rava.
The stretch between Sotah 11 and Sotah 15 contains over 3900 words without either scholar; this is by far the most (followed by 3275 words in Zevachim 111--116).
A 5-daf stretch not containing Raba or Abayei is between Meilah 21a and Tamid 25b.
There is another 5-daf stretch, from Tamid 29b through Niddah 3a, that does not contain either Abayei or Rava. Maybe it's cheating because the last few chapters have no Gemara, only Mishna. Also, if you count the 4 daf of Middos which are printed in the Vilna Shas after Tamid, you get a stretch of 9 daf.