miss/stumble when cruising

[donthedrummer]

Hi Folks,

I'm hoping someone can help me troubleshoot and correct a problem that has been dogging me for a few years.
My '95 K1100LT has developed a bit of a miss at cruising speeds. It seems to start/run/idle/accelerate just fine but if holding a steady speed, it has a subtle 'miss' that becomes quite annoying. This can even be felt at highway speeds. Sort of like you are getting a lot of wind gusts- if you know what I mean .I have put gallons of fuel injector cleaner through it as this seems very similar to a problem I had with my first K bike in the mid 80s. The problem went away immediately when I ran some treatment through the tank.
I have also tried new (from BMW) plugs and replacing one supect (and expensive) plug wire.
The condition persists at all engine and ambient temps.
Has anyone encountered this before?

Don

[johnny]

greetings donthedrummer...

i would do this...

unplug the motronic connector and clean the contacts...
unplug the 4 pin that goes to the gas tanks and clean the contacts...
tighten spark plugs...
unplug spark plug wires and check ...
tighten all grounds and battery terminals...
work your ign key back and forth a few time from full steering lock to on...
work your kill switch back and forth a few times full left to full right...
keep an eye on the clock and dash lights when it misses...

enjoy...

j o

[mystic red]

How many miles on this bike?

As for spark plug wires I would  advise going this route.

[donthedrummer]

Thanks Johnny, red,

The bike has 106,000 KMs (around 55,000 Miles).
Doubt if it's plugs or loose wires. Problem would have disappeared with my installation of new ones. I know what happens with a poor wire to plug connection. Had it before.
I will try the other avenues.
I'm pretty certain it's going to wind up being a D'oh moment or "I would never have guessed".
It just feels exactly like a slightly fouled injector. I even had them out, sent them to a forum member for servicing and they checked out perfect. Re installed with a bit of silicone grease, checked with propane for intake leaks -driving me nuts. There's no one I can trust in this city to be competent to troubleshoot/repair this problem. There are few tasks that I would be comfortable in having our technicians undertake.

Don

[jav37]

I am having the same issue with a 1997 K1100lt. I would also check the fuel shutoff system. When the computer gets a signal the bike is in a deceleration condition it shuts off the fuel to cut emissions and save fuel. If it shuts off the fuel too soon and intermittently it should produce the same result. If there is an adjustment that may be all it needs, if not a butterfly switch or ?? may need repaired or replaced.
My thoughts only, very new to BMW's

[Grim]

My 95 was giving erratic issues and it was solved by cleaning the Motronic plug as Johnny advised. Also check grounds and vacuum leaks. 
The rubber boots (BMW calls them Grommets) between the throttle bodies and the engine are known to fail with age and develop leaks as is the O rings under them. Damn near impossible to see the crack but they are there. Deceleration would make for a LOT of issues.
I also have just found the check valve under the tank for the tank vapor recovery fell apart with age. Do the "Air accumulator mod" and get rid of that line.  $4 part# 16132307467  http://www.motobrick.com/index.php?topic=989.msg3961#msg3961

[K75RT Keith]

Caps on the vacuum port nipples old and cracked?  Main ground wire connections clean and tight?  Crap in the bottom of the air intake box?

[donthedrummer]

Did a visual check on all rubber parts. Tried running propane all over the place while engine idling. No leaks that I can detect.
Wouldn't crap in the intake box have more of an effect on high rev/load conditions? Idles fine. Accelerates fine.It just has a miss that's noticeable at steady speeds.
I'll be out as soon as I have time to clean up some contacts.