K 1100 Starter Motor locked on

[Monkeyman]

I recently put a new battery in my 93 K 1100. I connected the positive terminal first as instructed in the manual, but as soon as I touched the negative terminal to the battery the starter motor fired until I removed the wire from the terminal. It did this with the key off, the key removed, and in the kill switch position. Any solutions?

 

[wndsrfr]

Relay Welded

Based on the intelligence gained by previous threads here, I'm betting that the starter relay contacts are welded shut from attempts to start with the old, dying battery. The low voltage, high amperage situation set up by a dying battery will overload the contacts and weld them closed. Installing the new battery just shoots the power across those welded contacts & viola! the starter runs.

Pull the relay, pry it apart and give the contacts a good burnishing with 220, 400 and then 600 grit wet/dry sandpaper---betcha it'll work fine for many miles.

 

[kioolt]

When you had your old battery in the bike is when the starter relay contacts welded closed. You may be able to get it unstuck by tapping on it. It is located under the tank in the relay box.

 

[Monkeyman]

Thanks for the info

I appreciate your insight. I have been hearing that this is a fairly common problem with this particular bike.

 

[CustomSarge]

Real common

Especially at start of season. Some replace the battery frequently to be sure, others don't for many reasons.

After the 3rd incident (on 3 different bikes), I built a solid state version; now 4 years of no trouble. The trick is in the thermal protection of the switching transistors. Good Hunting... <<<)))

 

[cjack]

I appreciate your insight. I have been hearing that this is a fairly common problem with this particular bike.

Sometimes...not often, but sometimes you can...all very quickly...connect the battery, turn on the ignition and tap the starter button repeatedly and the relay will release. Saves going into the relay box, etc.

 

[BUDDINGGEEZER]

I have had the same thing hapen to me on my K100LT. I would suggest installing a new relay. The problem with hitting the relay is the contacts are still pitted and will probably stick again. The other problem is with the relay under the tank and one needs to remove the tupperware to remove the tank, this would be a big pain in the rear to do on the road.

I bought mine at Beemer Boneyard for around $58. If it happens again I may relocate the relay with aftermarket relay. The BMW rerlay is 75 amp.

Just my 2 cents.

Ralph Sims

 

[mrich12000]

Use a ford selnoid never messes up

 

[CustomSarge]

Caution advised...

using other starter relay types. The negative side of the relay coil is a transistor in the engine controller: disables starter at ~ 850 rpm.

Stock relays draw ~50mA by the coil, most other starter relays are Way over that. IMHO that contributes to contact welding: fairly low magnetic force.

You could use the stock relay to drive a more robust relay. It's only a matter of wiring & space. Good Hunting... <<<)))

 

[cjack]

using other starter relay types. The negative side of the relay coil is a transistor in the engine controller: disables starter at ~ 850 rpm.

Stock relays draw ~50mA by the coil, most other starter relays are Way over that. IMHO that contributes to contact welding: fairly low magnetic force.

You could use the stock relay to drive a more robust relay. It's only a matter of wiring & space. Good Hunting... <<<)))

BMW makes a replacement relay kit that has a protection in it to prevent starting in the case of low battery voltage. It costs around $200 or more. It came out with instructions for the K12LT, but of course will fit any K bike. The K bike relay has not changed since 1985 until this retro kit for the LT. I think it would be a little tight to get it into a K100/1100 relay box.
.

 

[owrstrich]

fyi...

there is a starter relay for $30 here...


http://smithduck3.home.comcast.net/kbikeparts/kbikeparts.htm


you gotta eat...

owrstrich

 

[Monkeyman]

Problem solved

I took your advice and pulled the starter relay. You were right on target. I cleaned it up, replaced it, and it started right up. I absolutely love this forum. I couldn't have figured this out without all of the great troubleshooting and advice from so many people.

Now I'm going to order the starter relay that was listed in one of the replies just so I'm ready the next time (since it appears that this is a common issue). In the meantime, I can hardly wait to get back on the road. Thanks a million to everyone who replied. I have already learned a ton about maintaining my bike.