Hello, I have a slight issue with my battery, I havent been able to ride the bike for a few weeks and the battery was flat
so i charged her up and once the charger is off the bike wont start like battery is flat, with the multi meter the voltage is dropping so I think that the battery has shorted out,
is there a way of unshortening a battery ?
I can jump start the bike and ride her around but once stpeed it wont start again

I'm a newbie but I found out the hard way that when you drive your bike with low voltage it can lead to many other problems. In my case low voltage caused the Starter Relay to burn out after about 5 days of moderate riding. Uf you have a battery tender keep it on as often as possible, avoid short trips, and replace your battery asap.
To be completely honest I paid $125 and ordered a new battery today... AND a new Starter Relay ($48).
-JR 1988 K100LT

If the voltage is dropping while you watch then it is kaput and there is no way of regenerating it that actually works. There are many products that claim to fix it but all are only short term. Bite the bullet and get a gel battery they are a bit more but well worth it as they last longer.

When buying a new battery, we have many choices this post should help you to make the proper decision when buying a new one.
This following is off DEKA's pdf sheets. They are the largest independent battery maker in the world. ( and a USA factory )
http://www.dekabatteries.com/default.aspx?pageid=510

What is a gel battery?
A gel battery is a lead-acid electric storage battery that:
• is sealed using special pressure valves and should never be opened.
• is completely maintenance-free.*
• uses thixotropic gelled electrolyte.
• uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in a flooded
lead-acid battery (particularly in deep cycle applications)
• is non-spillable, and therefore can be operated in virtually any position.
However, upside-down installation is not recommended.
* Connections must be retorqued and the batteries should be cleaned periodically.

What is an AGM battery?
An AGM battery is a lead-acid electric storage battery that:
• is sealed using special pressure valves and should never be opened.
• is completely maintenance-free.*
• has all of its electrolyte absorbed in separators consisting of a sponge-like mass of matted glass fibers.
• uses a recombination reaction to prevent the escape of hydrogen and oxygen gases normally lost in a flooded
lead-acid battery (particularly in deep cycle applications).
• is non-spillable, and therefore can be operated in virtually any position.
However, upside-down installation is not recommended.
* Connections must be retorqued and the batteries should be cleaned periodically.

How does a VRLA battery work?
A VRLA battery is a “recombinant” battery. This means that the oxygen normally produced on the positive plates of all lead-acid batteries is absorbed by the negative plate. This suppresses the production of hydrogen at the negative plate. Water (H2O) is produced instead, retaining the moisture within the battery. It never needs watering, and should never be opened as this would “poison” the battery with additional oxygen from the air. Opening the battery will void the warranty.

What are the differences between gel batteries and absorbed glass mat (AGM) batteries?
Both are recombinant batteries. Both are sealed valve-regulated (SVR) – also called valve-regulated lead-acid (VRLA). AGM batteries and gel batteries are both considered “acid-starved”.
In a gel battery, the electrolyte does not flow like a normal liquid.
The electrolyte has the consistency and appearance of petroleum jelly.
Like gelled electrolyte batteries, absorbed electrolyte batteries are also considered non-spillable – all of the liquid electrolyte is trapped in the sponge-like matted glass fiber separator material.
The “acid-starved” condition of gel and AGM batteries protects the plates during heavy deep-discharges. The gel battery is more starved, giving more protection to the plate; therefore, it is better suited for super-deep discharge applications.

Due to the physical properties of the gelled electrolyte, gel battery power declines faster than an AGM battery’s as the temperature drops below 32ºF.
AGM batteries excel for high current, high power applications and in extremely cold environments

Your best bet is to put a new battery for your bike. A low voltage / current battery is giving you other undesirable electrical problems. Your ECU will be out of order because of this low voltage / current.

I had experienced the problems.

Cheers.

Had the same problem, although mine turned out to be a corroded ignition switch after a few weeks out in the rain while clearing my workshop out. I would charge the battery but it was weak very soon and then nothing BUT I thought the battery was weak until I removed it and checked it on the bench and it held power well, then when i refit it to the bike the ignition switch actually fried with smoke and when i removed it the back was all corroded so had been draining the battery whilst charging on the bike. now she is indoors and trickle charged via 12v socket and I've fitted a gel battery.

When I bought my 1985 K the battery was knackered so the garage fitted a new one before I rode it away. It then sat for a couple of months and when I tried to start it the battery was flat - removed and tested it and it was just capable, after recharging, of supplying 4 Volts. The moral: keep your battery on a maintenance charge when you're not using it - the clock and other odds and ends draw a small current which will flatten the battery in time (my GS1200 was the same).

Could be a bad earth....check that out first....! Ajays

If you remove fuse #3 (The 4th one down from the top), you should not measure any drain on the battery.
Apart from the clock, a couple of 'devices' get a permanent positive even if the ignition is turned OFF
One of them is the flasher unit: Because the K100 is fitted with a 4 way flashers, the unit is always powered.
The 2 other relays are the starter relay and the load shed relay.
The plug for the alarm and the one for the 'special' equipment get also a permanent positive.

And here it is.
The ultimate, definitive Idiots Guide on how to remove The Battery from a 1986 K75C.
I should know - this idiot just did it.

Remove side panels
Open seat and prop it up
Remove lid from tool tray
Go round to the brake pedal side of the bike and squat down looking at the end of the battery
Directly in front of your eyes is a bolt running from top to bottom in the middle on the end of the ECU tray which runs crosswise under the tool tray
Remove this bolt and its rubber washers completely
Go round to the gear lever side of the bike and squat down looking at the end of the battery
Remove the cover on the end of the ECU unit below the tool tray
Directly in front of your eyes is what looks like a big kettle connector mounted on a fat cable on this end of the ECU tray which runs crosswise under the tool tray
Follow the run of the fat cable and snip away any zip ties or anything else holding it to the frame
The entire ECU box with cable attached now pulls straight out
Wiggle, woggle the tool tray out
Disconnect the battery terminals - first negative
The huge original equipment battery will now not fit through the frame bars for removal
On the basis that it is now scrap anyway twist it around against the water bottle until it is on its end and pull it out

I have no idea how that hole in the tool tray with the metal component on the tank side is supposed to release the big kettle connector but I am delighted that it did not work and that subsequently a 24 year old main electrical connection has Remained undisturbed.

I have used this method and it makes life easy, I added a tie strap to ensure it remains well connected.
This not my write up but a copy from a well informed fellow K rider.
Ajays

Stick screwdriver in hole in bottom of tooltray. You should be able to see the clamp through the hole. Push clamp to the rear of the bike whilst loosening the plug. You need about 6mm or 1/4"