Help me get my '85 k100 running again

[CCalms]

Here's a video of the bike's current condition



Does anyone have any ideas? I really want to get out riding again!

[rbm]

Clean the starter as you mentioned and you probably will need new brushes in the process.  Have you gone through the electrical connections and checked that they are sound (i.e. used a good cleaner like DeoxiT)?

[CCalms]

I've gone at the main grounding point (the one that goes to the negative terminal) with some sandpaper but that's it. I've done some basic snooping around for damaged wires and I've checked various plugs (ECU, tank connection... I guess that's it). Any advice/links on where to look? I'll get some electrical cleaner.

[rbm]

The start motor is part of the grounding system for the electronics on the bike.  So, tackle that cleaning first to see if your symptoms disappear.

[The Mighty Gryphon]

It is worth the effort to get DeOxIt.  There are contact cleaners out there that dissolve plastic.  God only knows where you're supposed to use them since almost everything has plastic in it these days.  DeOxIt is the only stuff that is definitely known to get the job done without destroying everything else. 

It sounds like you may have an incorrect fuel/air mixture.  Does the exhaust smell like raw gasoline?  Have you pulled the plugs to see what they look like?  With everything you have changed so far, I think I would start looking at the sensors that send mixture control signals to the computer.  Specifically, the mass airflow sensor and the engine coolant temperature.  The problem could be a loose connector, or a bad sensor.   There are threads here that go into a lot of detail on troubleshooting these parts.

[CCalms]

I've cleaned my starter, EFI plug, and main ground with DeoxIt. No more starter or headlight issues, but the bike still won't start. I'm tempted to spend money on new spark plugs (the current ones are not old, just dirty...) and fuel stabilizer but I think I would just be throwing away cash. There is some real issue that I need help locating.

[Martin]

After you have tried to start it are the plugs wet or dry? With a plug removed earth it and crank it over, do you have spark?
Regards Martin.

[Laitch]

Where is the instrument cluster?  Did the bike ever run well without It?  What is in its place?
To echo Martin here, does each spark plug emit a bright spark?
Is each spark plug connected to its correct coil fitting? How did you verify that?
Is each cylinder test port capped?
Did you perform the Hall Effect Sensor (HES) test recommended in response to your first post, or were you unable to get the bike running enough?
You've checked and eliminated certain causes by cleaning and replacing parts. An orderly measurement process seems to be indicated if sufficient spark is being delivered to the correct cylinders.
Watch this video.

[CCalms]

Currently with full choke and no throttle the bike fires for 0.5-1 seconds and dies.

[Laitch]

The bike did once run quite well although with intermittent failures.
The instrument cluster was removed as it didn't work. I never needed to bypass anything and the bike was able to run without any cluster attached.

Just to clarify, CCalms, the bike was able to "run quite well" without the instrument cluster but had "intermittent failure." Please describe what "quite well" means and describe the intermittent failures, their frequency and their duration.

[rbm]

Have you tested the items that Gryphon suggested -- temperature sensor in the stand pipe and the mass airflow sensor.  Follow the steps outlined in Bert's diagnosis page  http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm
specifically for the temperature sensors.  Also, remove the MAF and make sure that it is operating properly, both mechanically and electrically as per Bert's guidance.  The throttle hesitation seems to me to point towards fuel starvation.  That can come about from blocked fuel delivery (all of which you have replaced except for the pressure regulator) or poor fueling (which you need to check).

[Brad-Man]

I would definitely run a check on the AFM...

[tsnap]

A tip I learned years ago, when everyone insisted that I NEVER try to clean my MAF on my  multiport 1989 Z28.

When cleaning, use brake cleaner  sparingly, carb cleaner contains lube(oil that can affect heating and cooling of the sensor wire) which leaves a film.

Also , flush part in reverse, pushing contaminants out in reverse of normal air flow.

Has always worked for me, FWIW

tom

[K1300S]

When cleaning,  use spray cleaner designed for MAF, not carb or brake cleaner.   It is available at any auto parts store.

[tsnap]

oops, I meant starter fluid contains cylinder lube.  But now i am getting a can of maf scrub.  thanks.

 hard for old farts to keep up with new products.  Heck, do plumbers even carry big wrenches anymore?  For some reason, my dad thought I NEEDED TO KNOW HOW TO THREAD PIPE BY AGE 8?

RECENTLY HELPED ON A SHARKBITE PROJECT....GEEZ, WHATS NEXT.....PUSHBUTTON PHONES????

TOM

[Brad-Man]

Doesn't he have an Air Flow Meter (has a spring loaded flapper to measure airflow)

If so he needs to measure the resistance at various points...

[rbm]

AFM,MAF, MAS ... it's so confusing.  Yes, he's got the barn door.  It sometimes fails because it's electromechanical in nature; a wiper rubbing against a resistive circuit.  So, dust gets in the way, springy metal stops being springy after 30 years, etc. etc.  There are tests that can be performed which are outlined in Youtube videos.  These same videos also show repairs that can be made in case something isn't right.  If the AFM/MAF/MAS/what-ever-you-want-to-call-it fails to work right, it will upset the fueling and may show up as the symptoms here.

[CCalms]

Took the multimeter to my EFI plug today. The resistance from the water temp sensor was correct for the ambient temperature.

[The Mighty Gryphon]

Hoping this fixes it.  Please keep us posted on how things work out.

Cheers

[tsnap]

waiting for a post that says it runs like a striped ape,better than ever,  and that he loves his bike so very much again!!

LOL, thats how it works for me!

tom

[rbm]

Here's hoping it works. :beer:

[Brad-Man]

Wonderful news !

Hope that's all it is.

[gpcrane]

I hope the AFM solves your problems.  I too have been having grounding issues.  It was the classic starter motor would not work, the load shedding relay was not pulled in.  So I removed the starter motor and cleaned out 29 years worth of carbon.  I measured the brush length, the shortest one was 10mm, according to my Haynes manual the min. length is 6 mm.  I put everything back together and the bike fires right up, good as ever...until...

As soon as I push the bike off the center stand the engine dies.  I try starting again, the starter motor turns but no ignition.  Back on the center stand and it firers right up.  After a few times going back and forth with the center stand it is running off the stand and I ride a way for a test ride.

The bike feels normal, running great.  I stop for gas, and have no problems starting the bike and coming off the center stand.  I ride for a few more miles and the bike begins to cut out, lights stay on.  Then the bike dies.  Once again it will fire up on the center stand but dies off the stand.  I go back and forth once again and ride it home with no problems.

My first plan of attack with be to clean all around the center stand and check all grounds.  Pull the EFI connector and clean it up real well.  Any other thoughts out there?

Thanks.

[John Lang]

Is there a side-stand cutout switch on that model? If so, is it somehow shorting out when the bike rolls off the center stand?

[gpcrane]

It's an 87 K75 s.  As far as I can tell I do not have the switch, but it sure acts like I do.  After cleaning under the bike and cleaning various connectors the problem is now worse.  I have a hard time getting it to fire up even on the center or side stand.  Once it does start coming off the stand kills it.  Lights stay on and starter motor still works, no ignition.

Thanks, Greg