Maintenance Rooms (originally called "Combo Rooms" in early demos of the game) are locations in Dead Rising 2: Case Zero and Dead Rising 2. They are workshops where combo weapons can be made, and often have the items for a combo weapon introduced at this point. They are located throughout the town of Still Creek and the city of Fortune City.
The Combo Bay is a motorbike trailer left behind by Leon Bell after his confrontation with Chuck. The Combo Bay is a special Maintenance Room where Chuck can build Combo Bikes, or repaint his motorcycles by combining them with cans of spray paint.
The Combo Bay can be found parked on the Silver Strip, just outside the front entrance to the Yucatan Casino.
Examples of Combo Bike designs are posted on the inside of the trailer,such as the Slicecycle, the Machine Gun Motorcycle or the Rocket Launcher Motorcycle to name a few, but crafting any of them will not create a Combo Card or Scratch Card.
In Dead Rising 2, Zombies can enter them unless you close the door. Later in the game, the rooms can be flooded by Gas Zombies in seconds unless you close the door.
In Dead Rising 2, Leon Bell can be literally, trapped in the maintenance rooms. Then either shot to death or, at risk of being hit with bikes chainsaws, bluddgeoned to death.
In Dead Rising 2: Off the Record, the Combo Bay belongs to Chuck. It has been vandalised by someone who clearly isn't a fan of his (and perhaps not a fan of Frank West either as there's a nearby cutout of him with a Bowie Knife in it).