The Sportster motorcycle (known as the XL) has been in continuous production by Harley Davidson since 1957. Motorcycles can be especially hard on batteries, mostly because they tend to sit for long periods of time without use. If you live in a climate that is too cold for winter riding, make sure to keep your Sportster's battery fully charged. You might want to invest in a "trickle battery charger" which can keep your battery fully charged without overcharging.
Remove the seat. Remove the Phillips head screw at the back of the seat. Then slide the seat backward to remove the seat.
Disconnect the strap that retains the battery cover by removing the bolt and washer on the right side of the cover. Remove both the retaining strap and the battery cover.
Lift the battery upward to obtain access to the positive and negative terminals.
Unscrew the bolts that connect the positive and negative battery cables to the battery.
Lift the battery from the motorcycle.
Slide the battery into position in the battery case.
Lift the battery to gain access to the battery terminals. Connect the positive cable (red) to the positive battery terminal (+). Connect the negative cable (black) to the negative battery terminal (-). Reinstall the bolts that connect the cables to each terminal.
Reinstall the battery cover. Slide the battery strap over the cover and reinstall the bolt and washer that secures it.
Reinstall the seat. Place the seat over the battery case and slide it forward so that the hook on the front of the seat engages the tab located directly behind the gas tank.
Reinstall the Phillips head screw that secures the back of the seat.
If there is corrosion on the ends of the battery cables, clean them with steel wool before installing the new battery.
Make sure the new battery is fully charged before installing it. Attempting to start the motorcycle when the new battery is not fully charged can damage the battery.