Couple of friends joined and they want to level fast. Where would they exp from 24 to 27 without Kazham ? Also, bibiki bay is at 27 right ?

You should look to party in Bibiki Bay around 29~ish or higher (you could get away at 28 with some heavy damage dealing jobs with food).

Depending on how you've decided to level, you could either try finding more Valkurm Dunes/Qufim Island parties to bridge the 26 -> 29 gap that Qufim Island to Bibiki Bay.

Depending on your friends jobs and their weapon choices you could easily trio Pugils at 26 with food items with external help (if any of your friends are WAR this option can work, I chain #4 Pugils with my main healing from outside and quickly leveled), and the exp reward should be greater due to the lower party member count.

If you're really stuck still, you could always just solo the levels on clippers at the outpost in Qufim Island till you ding 29 or 30, and move onto Bibiki Bay.

You could always get your kazham airship pass as well. I solo'd it at 28whm or so, it really wasn't that bad.

You could also send one of those mentors a tell asking them to help out.

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Pepsi - 75SMN - 88 cooking 12 fishing and rising
Sprite - 75PLD - 99.6ww 60alch 60gs 55bs 25cc 22bc
Coke - Best mule ever

you can also do carpenters landing from 26-29 easy very fast xp only holds 1 pt tho