How To Check a K Battery WITHOUT Disconnecting The FI Computer

By: Sam Lepore
March 1999

[Scott Jenkins business card] Credit Due: The information for this article came from Scott Jenkins, a wizard mechanic who also happens to be the Service Manager at BMW, Ducati, and Triumph of Marin in San Rafael, California. Thanks Scott!
Sometimes motorcycle batteries seem to last forever. Or, sometimes they make you wonder why the average life of a motorcycle battery is so much shorter than the average life of a car battery. I mean, after all, a bike battery is smaller than a car battery so it should last longer, right? Maybe. Probably not.

While I have had relatively good experiences with the longevity of BMW batteries on my R100RT, my 1995 K75RT is on its third battery in three years. The first two were made during what I later heard was "a bad batch from Spain" (?) and the second didn't even last three months before it went flat.

So all of this convinced me that even though I used to check the R100 battery every other month or so, I would have to pay much closer attention to the K battery. Fearlessly I removed the sacred document known as the Rider's Manual from its honored resting place in the tail cone of the K75. Happily I turned to the official ritual for checking the battery ... Fearfully and sadly I returned the Basic Beemer Bible to its tabernacle.

Disconnect the Fuel Injection Computer ??? After the problems I've heard on the IBMWR list about mistreating that unit, I was, shall we say, reluctant. Ahhhh, what the hey. Let's give it a try.

  1. Follow instructions very carefully.
  2. Curse instructions vociferously ... that FI connector is not going to budge without a LOT of force.
  3. Re-read instructions carefully.
  4. Re-curse at lack of recourse ... pry the connector with a screwdriver ??? who are they kidding?
That's when Scott came to the rescue. At my next visit with the friendly staff at BMW Marin, I mentioned that I couldn't get to the battery. When Scott smiled that "You dumb ***, you should have asked me first. :)" smile of his ... I knew, well, I should have asked him first.


Here is a simple way to access the battery WITHOUT disconnecting the Fuel Injection computer:

1. Remove both side panels.

The K side panel has a three-point mount, consisting of a pop-grommet at the upper front, an open hook around a post at the bottom, and a plastic pin-in-socket at the upper rear. Photos 1 and 2 show the left side panel. Pull firmly but smoothly with your fingers under the panel as close to the grommet pin as possible. You can use the frame tube as a visual guide. The grommet is attached to the side of the frame tube - on the side toward the rear of the bike. (Opening the seat may make it easier to see the grommet.)

Remove the side panels
[Left Side Panel before opening]
Pull the front at the grommet pin
Photo 1
[Left Side Panel after opening grommet]
Don't twist the panel out too far
Photo 2
Then move the panel vertically straight down to unhook the second mounting point. Finally, carefully and slowly pull the rear pin out of its socket. It may help to twist (rotate) it a little, but be gentle - this is soft plastic and is the most likely point to break.

2. Release the FI computer latch pin.

On the right side, just above the coolant overflow tank, a black plastic pin holds the FI in its cushioned mounting tray. The pin snaps into the rubber grommet that supports the tray on the overflow tank. It is easily removable with pliers and may even be pulled with strong fingers. Photos 3 and 4 show the pin being removed.

Release the FI latch pin
[Pliers on FI latch pin]
Use pliers or fingers
Photo 3
[FI latch pin removed]
Watch it ... this is a crevice seeker
Photo 4
3. Slide and pivot the FI computer out of the tray.

Start pushing the FI computer from the right side where you removed the pin, and guide it with your left hand so it comes out, slightly down, and slightly back. The FI connector cable is probably zip-tied to the frame, so you should work this around the frame as the unit slides out. There should not be any strong force or binding anywhere in this movement. If something is "stuck", stop and see what it is. The very first time you do this on a bike that has seen some years on the road, the unit may be snug because of accumulated gorp (which is a highly technical description), but once it moves it should slide easily. Photo 5 shows the slight down/back angle of the FI computer just before it is clear of the tray. Pull it all the way out and let it hang.

Then remove the plastic tray. It sits on four rubber mounts and slips out up and back. Photo 6 shows the tray being removed. There are three grommets on the tray itself which cushion the FI ... make sure these stay where you can find them later.

Move the FI, Remove the tray
[FI unit at edge of tray]
Slide FI out, slightly down and back
Photo 5
[Tray being removed]
Slide tray out, up and back
Photo 6
[FI out of the way]
Just hanging around for you
Photo 7
4. That's it !

You now have access to the battery from the top and the FI connector has not been traumatized by your assault on the battery. :) Photo 7 shows the FI hanging from its connector.

Don Eilenberger added: "IF you've replaced the BMW battery with another brand - the positive terminal may not have the very nice insulating cover over it that the factory battery has. In this case - it would not be difficult to short the case of the komputer on the positive battery terminal.

This would NOT be a GOOD THING. It could easily cost you a new komputer, or perhaps a wiring harness. To avoid it - I always place a piece of cardboard directly over the battery terminal so it can't short."



When putting it all back together ...

Putting it back is just as easy. Position the tray on its four mounting points. Slide the FI computer into the tray. Again remember to work the FI cable around the frame as you slide the FI into the tray.

Before you put the FI latch pin in, be sure the three cushion grommets on the tray are in their proper grooves and the FI is not resting directly on the tray.

The FI latch pin makes no sound when it snaps into place. Verify the head of the pin makes contact and is flat on the FI flange so it does not work itself loose.

Be gentle again when installing the side panels. The rear pin just barely goes into the socket ... line up the bottom hook under its post, then press the upper left pin into the grommet. A little rubber-friendly grease on the pin will make the next removal a lot easier. Greased or not, the pin makes no sound when it snaps into place. Give it a tug to be sure it is seated.

Sam Lepore,
San Francisco
[The bottle says 'RAT BASTARD Root Beer'] (The bottle says 'Rat Bastard Root Beer')

 

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