I have a low mile 1985 K100RT. Runs rough and nearly cuts out when cold. After riding for 5-10 minutes it clears out and seems to run great. What I have done:

Clear, non-ethanol fuel
Checked fuel at Injectors
New injectors
Wriggled wiring
Fuel pump working great


Help??

Never hurts to reseat the L-Jetronic connector under the seat and the ICU connector under the tank at the very front behind the steering head.

Check the resistance on the coils and spark plug leads as described here:

http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/efi-web%20page/K100%20troubleshooting%20Starting.pdf

When it comes to K-bikes, idleness and low mileage aren't necessarily preservatives. A tuneup should be on the schedule.

How about cleaning the electrical connection plugs under the tank and verifying their secure fit, cleaning and tightening the battery post connections, cleaning and tightening the battery transmission ground and frame ground connections, cleaning the air filter, replacing the fuel filter, verifying that the spark plug gaps are correct or replacing them with correctly gapped new plugs, verifying that the spark plug leads are firmly attached to the plugs, checking the valve clearances, balancing the throttle bodies, adjusting the idle and adjusting the throttle position switch? All this exercise is collectively known in a few far-flung outposts as a tuneup. If the stumble isn't gone afterward, you can still advertise it when you sell it as having had a recent tuneup.

How many miles on the bike and how many have you put on it? Is the interior condition of the fuel tank clean and free of glop? A bike in good fettle will run well on good quality mid-range octane gasohol; mine does, anyway or it could be I don't know that it's running poorly.

Don't wake me.  

Just had all the electrical connections checked out. The bike has 25K and the tank appears to be clean. Don't know the time on the filter?? 

Thanks for the suggestions.

Dennis

skypilot2 wrote: Don't know the time on the filter?? 

The OEM filters have dates on them. Tossing it out will make its date moot except to fuel filter collectors. Consider replacing it.

Don't waste money on a BMW fuel filter. Just get a 3032 at NAPA for 4 or 5 bucks.

The air filters are way oversized for a 1000cc engine so just blowing it out should be fine.

Its possible you may have an air leak or two in the induction. Rubber bits tend to disintegrate over time. A typical culprit is the crank case breather tube at the back of the airbox. Z-shaped tube which goes into the plenum.
Have a read of the 'Troubleshooting' link on the Portal tab. Practically everything is in there that you'll need to get your K running sweet.

Holister wrote:Its possible you may have an air leak or two in the induction. Rubber bits tend to disintegrate over time. A typical culprit is the crank case breather tube at the back of the airbox. Z-shaped tube which goes into the plenum.
Have a read of the 'Troubleshooting' link on the Portal tab. Practically everything is in there that you'll need to get your K running sweet.

The engine breather hose are relatively cheap ( $30 ) to replace and a likely culprit, first thing I change along with air filter , fuel filter , plugs as soon as I get a K100 and then as Duck suggested clean and make sure a good fit to the fuel injection processors connector under the seat above the battery ( aluminium box ) and the ICU connection.

Thanks everyone. Have it torn down all over the floor. Have cleaned and reseated the connections suggested, changing the fuel filter (was a 2011 date on it) pulled the Z tube and it was cracked and someone had put electrical tape on one end to hold it together. Where is the best place to find the Z tube? 

Thanks all for your help. Will let you know when it goes back together as to a fix.

skypilot2 wrote:Where is the best place to find the Z tube?

A BMW dealer. I use MAX out of New Hampshire. You'll have somebody over there. The part isn't costly.