K1100 LT Intermittent engine sputter

[EJnCO]

Greetings to all fellow K bike riders/owners!
I am new here on this forum & after reading the many blogs & forums elsewhere till I am blue in the face, I have come to the realization & conclusion that this is the best well informed & knowledgeable forum out there in cyberspace for BMW K motobrick machines! Many thanks to everyone in advance!
I am experiencing a rather strange & somewhat scary electrical?/fuel delivery? issue on my 1993 K1100LT. I say strange because it doesn't happen but maybe once or twice a year. I also say scary because I am usually 100+ miles from a decent cell phone signal or from civilization. The thought of being stranded in the middle of the Colorado Rockies high on a mountain pass doesn't sit with me very well.
The bike is up to date with it's air filter/fuel filter, all fluids etc. Runs real nice when I get on it for a day but sometimes it acts up while cruising. My bike starts like normal, sometimes I have to give it some choke especially during the winter months when it's 40 degrees or so but during warmer months (like now mid 70's onward) I use no choke. Anyway, it starts up & runs like it has since the day I bought it 11 years ago. In the last 2 years or so, I have been experiencing this strange & scary issue & I just can not pinpoint what the problem might be. (It's obvious that it's either electrical or fuel delivery) When this sputtering happens, it feels like either it's starving for fuel or water in the fuel? or like the "electrical spark system" could be compromised somehow?? It usually happens while I am cruising & when it does happen, I keep the throttle revs up so it doesn't die on me while cruising & all of a sudden it sputters some more & then goes back to normal & runs like it should. During the time it's sputtering & I am doing the throttle up thing (to keep it from stalling completely), it feels like it's running on 2 cylinders & then it goes back to normal (it's about a 10-15 second hic up during this time). I do my regular maintenance on my K religiously & am a decent mechanic but sometimes I need extra insight from other K bike owners who are willing to help. This issue has me baffled & the sooner I can figure this out (of course with you all's help) the sooner I can feel more confident & continue to enjoy my retirement days. I am 62 & love this machine! Yea sure, I could fork out big $$ for a new BMW but there goes my hard earned retirement fund. Any positive ideas or suggestions from anyone will be very welcomed. Thank you & ride safe! Ej

[johnny]

i have a positive idea...

other than some breaks in that mega paragraph you posted up... wow...

if you are not prepared and do not expect at some point to be stranded on a high mountain pass one hundert or more miles from home... then you oughtta maybe perhaps not be riding a motobrick...

welcome to motobrick.com there ejinco...

now stop your freakin and commence to motobrickin...

j o

[EJnCO]

Hey Thanks for the reply J O!
Sorry for the long winded technical issue I have with my K1100 lt. I was just trying to explain what is going on with it in hopes that someone out there in Motobrick land would give me more positive reply than yours! I have been riding bricks since '85 & there is no way I freaking want to ride anything else....thank you very much :clap:

[mystic red]

Only does it once or twice a year, that's a tough one. I'm with Jo on this one. To quote him, " I would ride it till it doesn't move." It will be a lot easier to diagnose.  cool shades

[Bill]

While not familiar with K1100 s I will suggest the following steps:
       1. Look for some commonality in the occurrences, ie Ambient temp, engine temp, fuel level .....
       2.  Inspect and clean all connectors related to fuel, ignition control and spark.  Deoxit is highly recommended.
       3.  As it is so infrequent log everything with each episode.
       4.  Practice your german pronounciation  of Yes Misstress'   'Ja Herrin'  in soft loving tones.  Very difficult !


The last step worked with the ABS controller on my '88 K100 LT

[johnny]

greetings...

i gave you a positive idea as you asked...

now you are asking for a more positive reply...

here it is... after doing #1 just to say i did it... id do #2 and #3 here...

j o

[mystic red]

Also a list of what has been done to the engine, like new spark plug wires, intake bushings, gas lines, etc.

[kennybobby]

Your symptoms sound similar to the issue i had and recently solved.  Have a look in the workshop Child Boards under Low Revs.  Yours is not an Engine problem.

If you want to troubleshoot it you can do a really simple and quick test--pull the vacuum line from the rearmost throttle body and suck on it to see if it has a crack or might be leaking.  or use a mity-vac.

Or just put a fresh tube on there to eliminate that as a possible culprit and not get an oily taste in your mouth.  The auto stores only carry 2 sizes of tubing--too big and too small (7/32" or 5/32").

The OEM tube is 8mm OD and 5mm ID.  The fittings are different sizes between the throttle port (5mm) and the port on the fuel pressure regulator (6mm), which is impossible to get to without removing the air cleaner housing.  i got the larger 7/32" tubing since it fit the FPR better, then used electrical tape to build up the throttle body port for a tighter fit.  Or grease could be used to fill the gap and a cable tie to squeeze it tight. 

[EJnCO]

Thank you Bill & Mystic Red & of course J O for your suggestions & ideas. I do appreciate them immensely! Here is what I have done over the past couple years. New plug wires, new air filter, new fuel filter...you know the basic stuff which is done every 10K miles or so regardless if it needs it or not with the exception of the spark plug wires. I replaced them 5 years ago.The spark plugs however haven't been changed in a while (7 years) & I am in the process of R&R them as we speak. Well, not exactly as we speak but tomorrow morning. 2 years ago on my way back home from Big Bend NP, the OEM exhaust system literally was falling off & I had to replace that when I got home with a Remus system. It fired right up with the new exhaust & has been running smooth as silk as it has for the time I have owned this bike. I haven't done much to the motor except the usual basic stuff like adj. cam chain, & valves. The bike runs strong every single time I go for a cruise & this "hiccup or sputter" I have doesn't happen all the time. Being in Colorado the gas here has 10% ethanol added for the winter months & I stay away from those gas stations that have that in their gas but sometimes that is impossible. I don't know for sure but from what I have read on the web, It can not be good for these machines. I am also thinking perhaps it could be water in the gas? where I pump the gas? One can never tell if the gas is good or if it has water in it as you pump gas. The fuel pump works as it should. With what you have suggested, that gives me a better insight as to what I need to do to figure this out. I like Mystic Red's suggestion to ride it till it don't move & then diagnose it. I wish it weren't this difficult & I also wish I could determine whether or not it is an electrical issue (obviously it maybe?) or a fuel delivery issue. If there was water in the gas (then it wouldn't be an electrical issue) as it's being distributed throughout the fuel system as I am riding, it's sure to "hiccup" or "sputter" until that water passes through the intakes in the combustion chamber etc. am I right? or am I just blowing hot wads of hopeful & wishful thinking? :dunno2:
Anyway, I do appreciate you all's input on my "sputtering" problem & I will do my best to figure this out. THANK YOU for all your HELP & Suggestions!! Have a Happy Memorial Holiday weekend & always... Ride Safe! Ej

[TimTyler]

It's pretty easy to rule out bad gas. Just pour a bottle of HEET or Seafoam in the tank and run the engine for a while.

[johnny]

no line breaks... its not good... my fecking head is gonna explode...

[Scott_]

'93 1100LT = Ignition amplifier.
When was the last time you cleaned/renewed the heat sink paste....... known to degrade with age, and cause ignition issues when it overheats.

[EJnCO]

Ignition amplifier? Be gentle with me on this one...especially johnny! Where would the ignition amplifier be located at? I have no idea. Wait a second...got to have a "line break" here or Johnny's head is gonna explode.. :mbird

When I rode the bike the other day & it happened to me again & it happened 10 minutes after I started the bike. It wasn't even at normal operating temps yet. Temp gauge showed it was not close to where it is when it's at normal operating temps.  another line break....

I know you all will suggest that I don't rely on my temp gauge but one has to when that is the only option I got.

Anyway, I am going to tear into it in a few minutes & check every possible connection & with some luck, be riding by noon.

Thanks!

[rbm]

Renewing heat sink paste on the Ignition amplifier

Looks like this:

[EJnCO]

Thank you RBM for your help & the link. much appreciative! Ej