Removing & installing a battery
ALWAYS, on every battery you ever deal with, disconnect the negative terminal first and reconnect the negative terminal last. This is to prevent arcing (creating sparks - bad things to have right behind your fuel tank/carbs) and for general safety.
Negative is always marked with a minus (-) symbol, and positive is always marked with a plus (+) symbol.
The first step is to remove the seat on your 250. To do this, insert your key on the left side into the seat lock, which is located just above the helmet lock, as shown here:
Once your seat is removed, this is what you will see. The battery is located to the left, just before the two fuel tank bolts and behind the airbox (those two holes). There is also a black rubber strap that holds the battery in place.
This is what the battery looks like from overhead:
The POSITIVE lead is on the left and is RED. The NEGATIVE lead is on the right and is BLACK. Do not mix these up.
First, remove the bolt from the NEGATIVE lead on the right using a Phillips screwdriver. Leave the NEGATIVE disconnected until you are ready to button everything back up.
Next, remove the POSITIVE lead from the POSITIVE terminal. Notice that the positive side has a RED boot/cover. Here's what the POSITIVE lead looks like with the bolt removed from the terminal:
You may want to put the bolts back in place on the terminals temporarily to keep from wondering where they went. Make sure to remove them before you return the battery for the core charge, though. Your new battery may not come with these. Keep the old nuts and bolts as spares regardless.
After both wires are unhooked and moved out of the way, you can pull the battery out of the bike. There are two ways to get your battery out. Either one is pretty simple.
Reinstalling your battery
To put the battery back in, reverse the removal process. Make sure the positive and negative posts are on the correct sides, put the strap back on, hook up the positive cable, and then the negative.
If your bolt won't reach the nut
You will have noticed that the nuts for the battery post bolts have fallen to the bottom of the post when you removed the bolts. If the bolt is too short and you have trouble getting it to reach the nut (this is particularly true if you have added another wire for a charger or other accessory) follow these directions to get the nut in position so that the bolt can be turned onto it.
Remove the side fairings that start at the back edge of the tank (one Phillips bolt and then pull free from the one front and two rear grommet stays):
Then, insert the bolt into the positive terminal post.
This is why we removed the side panels: to provide access to the nut from under the frame. Use a flat head screwdriver to 'lift' the nut up high enough to screw the bolt back in all the way. The terminals are made of lead, which is very soft. Don't get carried away with the screwdriver.
Note that this is the negative side. Do the positive side first. We just don't have pictures of the positive side.
Now repeat the process for the right side to raise the nut using a flat head screwdriver, and then screw the bolt back in all the way. Once you are done, it will look like this (negative side again):
Your 250 will now look like this: