1993 K1100 LT ignition mystery

[Jesse54]

Hi folks. Situation- Currently on the road from the east coast and stranded on the west coast by my, (197,000mi), 93 bmw k1100lt. A few days ago ran fine and suddenly began missing on 2 cylinders. After it cooled off it started and ran ok till it warmed up and problem returned. Replaced the plugs, (#2 & 3) didn't look so good. Started fine-Back on the road again. Five miles or so and problem returned. Leads at the plug end of #2 & 3 looked burned. Checked output of the coils and found the one for #2 & 3 cylinders not putting out except for a second or two occasionally. Found a replacement set of coils and leads on e-bay with a great feedback rating. Made the swap with NO improvement. Swapped out the coil in question again with the original front one, just incase the new used one was also faulty. NO improvement. Checked the connection of the wires to the coil from the harness and the connection from the brain to the giant plug. Still no luck. Still stranded and cash will run out eventually. Anyone out there know someone who has seen this before??? Could really use a solution here.

[newnut]

i suspect rectifier, if not maybe cdi? i feel for you, electrical probs are the worst!!!! too easy to throw parts at it.

[Jon_W]

Ok, is there any fuel in the cylinders? What colour are the plugs and does it smoke when running??

[470four]

@ 197,000 miles I would take it off to the woods somewhere and come back alone... ;)


Buy a new one.

[jaagsxr]

yer its a bmw 470four NOT a ducati !!!! lol just run in lol

[Snowy]

Yes, it's both a BMW and a Brick so will go on forever if maintained.

Usual suspect for running OK cold and misfiring when hot is the HALL effect sensor. With the engine cold, heat up the sensor with heat gun (it's positioned at the front of the engine housing - I don't have my manual with me at work so can't tell you exactly where). If the bike misfires straight away that's probably the culprit.

Go to www.k11og.org and do a search on HALL effect sensor there's loads of info there plus instructions of how to heat it up on a cold engine.

I have assumed you have correctly switched over the ignition coils (firing sequence is 1/4 and 2/3) and leads to prove if the fault lies there.

It is worth trying a few other "usuals" to eliminate other rogue issues which can give similar faults:

1. If not already done, short out the sidestand switch to take it out of operation. Its the flat two pin connector on the RH side of the bike near the battery (one wire is green/blue if my memory serves and the other is brown which is earth. Just put a wire link across the two terminals. There are two similar connectors (one for the sidestand switch the other is the gear indicator so check you have the right one)

2. Clean up and make sure the four pin connectors on the fuel level sender/pump connection are good - this is the multipin connector found at the rear of the tank and goes to the RH side near the battery. It's a round connector.

3. Clean the connectors on the Motronic under the seat and make sure the big multipin connector is clean and seated properly.

I would have said coils straght away given your symptons but if you have 100% eliminated those then next best is the HALL sensor.

[Jesse54]

I want to thank you all for your thoughts and input. I've discovered and corrected the problem. It was the ignition magnifier located on the side of the battery box. Apparently it can fail one side at a time. $53. part and $60. for overnight drop shipping and 25 minutes to install. Runs great again. Spent the day in Oregon and visited Crater Lake. Impressive. Tomorrow - Walla Walla, Washington. Just want to see that a town with a name like that actually exists.