Now, our guild doing 10-man, we run with only 1 motor cycle, and take the extra person and pop them in a demolisher, so the Demo's always have a passenger for speed boosts and to scoop up extra pyrite.
Rules for Flame Leviathan:
Siege Drivers: You have 2 jobs. 1, run away when you're targeted and 2, interrupt flame vents. YOUR DPS SUCKS. So stop trying to hit flame levi with your ram and do your job.
Siege Gunners: DPS Flame levi when he's overloaded, otherwise, you're lighting fires, and shooting down pyrite.
Demo Drivers: You are the dps machines. MACHINES! Your job? Run when you're targeted. If you're not targeted, get to a spot away from whomever he's chasing, and keep rolling pyrite stacks. You see, its that wonderful pyrite that does the HUGE damage to flame levi. And its not just the shots of it. Its the rolling dot-stack on him. This means you also need to be aware of where the pyrite is, and move near it so your passenger can scoop up more. Try not to get below 25, so your passenger can speed boost you.
Demo Passengers: You have three jobs, scoop up more pyrite whenever possible, speed boost if needed, and shoot down pyrite from the air whenever possible as well.
Motorcycle drivers: You've got two jobs... try to lay tar in front of flame levi, and pick up passengers. When you can't do those two things... stay the heck away from him to avoid flame jets. Your puny gun is not worth dpsing with.
That's my tips and information on Flame Levi. For me, these simple rules allow us to down Flame Levi + 2 so far, with no one dying. We might try + 3 this week.