Battery Box Replacement
KTM offers a new larger battery box that can hold a larger, higher capacity battery.
Size comparison between two batteries. Refer to my article, Battery Information, for details about the various available battery sizes, charging, and maintenance.
Old battery box (part no. 590.11.055.000) versus new larger battery box (part no. 590.11.055.100). You can see that the new battery box mounts using the same mounting holes, but holds the battery lower in the air box.
Battery Box Installation
Here is the stock 2004 battery in my 525 EX/C. Remove the battery by first removing the two battery cables, then remove the two rubber straps holding the battery in.
Remove the three screws that hold the battery box to the air box and lift the battery box from the bike. Remove the starter relay from the battery box. It is rubber mounted on two plastic prongs.
Remove the rubber battery straps and transfer them to your new battery box. Install the starter relay and replace the battery box back into the air box mounting it with the three screws removed earlier.
Finally, install your new battery by reconnecting the cables and rubber straps.
For information on adding acid and charging a new battery see my article, Battery Replacement. Always keep your battery charged. Use a charger designed for motorcycle batteries. A car charger outputs too much current. For more information, refer to my article, Battery Charging.