We are happy to make a few suggestions: of course, because we're not in the hot seat it's easy for us to advise, but only you as teacher will know what might work or what won't.

Here are a few suggestions that came from our editorial staff (who have taught plenty of poorly motivated students). We don't recommend that you try them all at once, or you may prefer not to try any of them!

--find out what the kids are interested in (i.e. Fashion, skateboarding, music heroes etc), and relate some of the material studied to those interests. You can use our "search function" in the Teachers' Room to see if we have materials on those topics.

--present plenty of material about the culture that goes with the language.
Use songs, artwork, cartoons, whatever you can to help raise their interest.

--put the class into groups. Each group is self-reliant and with any task that group must work together to perform the task. You may have a leader, secretary, giver out of material and these roles are rotated in the group.
Small rewards or incentives may be given to groups who work well and finish a task: e.g. Less homework, a small piece of candy.

--have each lesson open with a short 'fun' activity. Our warmer section has some excellent ideas for this. Equally, finish class with something short and fun that revises something taught in the lesson. We think that most students, no matter what age love games/pair crosswords/group quizzes (in which they compete against other groups) and this increases their motivation. They may also begin to accept that they have to do some serious work as well.

--check that the work you are doing is meaningful and relevant (students know why they are doing it and what they have to do and it has a sensible mpurpose).

--try to find out how these students learn best. E.g. Because they are seen as non-academically inclined students, they may be more scared off by doing reading and writing. Doing more speaking work in pairs may help their motivation. Find out what strategies they use to learn.

--Invite one or two English native speakers in if possible. The students may be bored with you, but will usually welcome someone new. Prepare for the visit by looking at what the visitor does etc.

--Have a class party! Prepare for it by planning a menu, even cooking food together, choosing music, planning entertainment, inviting guests so that you work together with the class.

--adapt any material to your students' situation. I.e. Roleplays done with their lifestyle in mind etc

--get class to write a contract with you on what they want to learn, what will happen if they are not speaking English in class etc.

--ask each member of class or in pairs to teach you something in English.

OK, those were a few suggestions. In the end, unfortunately there isn't a magic formula, but hopefully, over time you will establish a rapport and find what works best for them.
Good luck with your teaching.