Electrical gremlins

[Filmcamera]

Hello fellow Motobrickers, it has been a while.  Luckily the bike has been running smoothly - until now


Here are the symptoms


It started with backfires when I rolled off the throttle at higher revs.
Then stalling when I came to a stop started as well (it always fired right up again)


Then it got serious


It started randomly running on only two cylinders (1 and 4)
I suspected a bad coil pack so I replaced it with a used one - same issue.


It runs like a champ and then suddenly goes to two.  Obviously that leaves me with very little power and twice I have got stranded goin up the steep hill to my house since it did not have the grunt to make the gradient (going up hill seems to make the issue more likely to happen).


When it does happen I tend to leave it WOT and rev the hell out of it and all of a sudden it will kick back in again (which has caused the bike to wheelie in lower gears!)
It seems obvious it is electrical but can anyone suggest the best way to track it down?


thanks

[rbm]

The K100 series gets its timing signal from the HES, one HES sensor per coil. Maybe one of the HES sensors is intermittent or the connection under the tank to the HES assembly is intermittent.
- clean the HES assembly connector under the tank, using Deoxit to clean the connectors.
- test the HES sensors to see if they are reliable.

[Filmcamera]

Thanks, I gave everything a clean with Deoxit as you suggested.


How do I test the HES? I actual installed it fairly recently, maybe a year ago, because the old one failed. When the old failed there was no intermittent anything it just died and the biked simply would not fire!


I had suspected coils because it is always the same two cylinders (2 and 3).


I will keep cleaning and cheing connetors today and see how it all goes.

[alabrew]

Reading what you are experiencing, it sounds like what I had on a very hot day when half of the HES went bad on Big Red.
IF I could get the revs up, she would go. I could also hear the fuel pump "pulsing" since it wan't getting both signals to pump.
I think changing the coil with no improvement points toward the HES, especially if it is occurring when hot.
That is kind of the test, if it runs fine cold and acts up hot = HES
You could try using a blow dryer on the cover to try and reproduce the symptoms.

[Filmcamera]

I took your advice and got a ne HES from Euromotoelectrics, that seems to have done the tric.  After installing it I took the bike for a 100 mile jaunt in the twisties and it only did it once early on for la minute then never again.


Fingers crossed


Thanks for the help!

[Filmcamera]

I spoke too soon.


The issues are still there, admittedly much less severe but still there.


I am going to try and explain what is happening in case anyone recognises the symptoms nad has a cure.


1. A slight hesitation when I roll on the throttle.  This is not huge and if I has not ridden the bike 1,000's of miles fo ryears I migh tnot even notice it.  However there is a definite lag from twist to go.


2. A severe lack of power when lugging (i know, I know don't lug).  That is a little simplistic though.  For example going up the hill to my house which I used to do quite happily at 3,000 in second I now need to be at 5,000+ in 1st or the power drops off so badly the bike wants to stall.  Even then in the steeper parts I have to slip the clutch to build the revs back up to stop it grinding to a halt on me.


So far I have changed one coil and the HES - I am very open to suggestions as to what to try next...

[milq]

I spoke too soon.



2. A severe lack of power when lugging (i know, I know don't lug).  That is a little simplistic though.  For example going up the hill to my house which I used to do quite happily at 3,000 in second I now need to be at 5,000+ in 1st or the power drops off so badly the bike wants to stall.  Even then in the steeper parts I have to slip the clutch to build the revs back up to stop it grinding to a halt on me.

Are you sure it isn't starving for fuel? Maybe a chunk of smutz floating around in a fuel line? I used to be in charge of maintenance on a fleet of early to mid-90s Chevy trucks, they would display similar symptoms when the fuel filter was plugged. revved fine in neutral but try to actually drive it and had to give it WOT and the exhaust almost sounded like it was plugged.

[Laitch]

Another possibility is that the side stand switch could be faulty. It could be creating an intermittent or partial disconnection that is creating this power loss. Bypass it then try another few launches up the hill to your home after the engine has been thoroughly warmed up.

Keep an open mind. Here's a relevant thread and here's a thread on disconnection. Other sources of this problem could be ignition switch contacts—although I seem to recall you cleaned those in the last couple of years—and leaning of the fuel mixture from air intake leaks. Have you viewed the spark plugs  after one of hill climbing events immediately after you arrived home?

[Filmcamera]

Are you sure it isn't starving for fuel? Maybe a chunk of smutz floating around in a fuel line? I used to be in charge of maintenance on a fleet of early to mid-90s Chevy trucks, they would display similar symptoms when the fuel filter was plugged. revved fine in neutral but try to actually drive it and had to give it WOT and the exhaust almost sounded like it was plugged.

That is a good idea, the fuel filter is one of the few things I have not changed since I got the bike, I have ordered one... and will report back.

[Filmcamera]

Another possibility is that the side stand switch could be faulty. It could be creating an intermittent or partial disconnection connection that is creating this power loss. Bypass it then try another few launches up the hill to your home after the engine has been thoroughly warmed up.

Keep an open mind. Here's a relevant thread and here's a thread on disconnection. Other sources of this problem could be ignition switch contacts—although I seem to recall you cleaned those in the last couple of years—and leaning of the fuel mixture from air intake leaks. Have you viewed the spark plugs  after one of hill climbing events immediately after you arrived home?

I have check the side stand and it seems ok, though I did have an unexpected failure of the fuel pump to charge the other day, a quick plug and unplug of the four pin fixed it.


When I checked the spark plugs though do show signs of running lean, I do think I need to find someone who can properly set the mixture, it is has been a finger crossed approach from me so far, the problem is there are not many mechanics here who have even seen a K bike let alone know how to set one up properly.

[Martin]

To check the mixture with the bike idling press the green starter button. If the mixture is correct the idle should stay the same or rise very slightly. If it rises significantly the mixture is lean, if it drops it is rich. You can adjust the mixture using the lean drop method or find somebody with an exhaust gas analyser that knows how to use it.
Regards Martin.

[Filmcamera]

Hello Martin,


I have heard that before and whenever I try is the revs stay exactly the same. I just did it again and same result, the revs stayed the same.


That might mean the mixture is fine or it could be that is another ones of those things that applies to 2v bricks but not 4v ones.


Hopefully the former!

[Martin]

Sorry I didn't see the 16v it only works on 8v.
Regards Martin.

[The Mighty Gryphon]

If the throttle position sensor is mis-adjusted it can affect performance.  Normally it messes up the idle along with it, but it's worth checking.

Do you know how to set the idle position on the throttle position sensor by grounding the pin on the diagnostic plug?   

Here's how you can do it.

http://www.largiader.com/articles/motronic.html

 "We can do a quick check of the TPS setting on Motronic 2.2 (and I think 2.1) using the 3 position diagnostic connector. I've tested this on my '96 R1100RT and it works.  I'll check my '93 K1100LT (MA 2.1) one of these days and let you know but I'm pretty sure it works the same and in addition, it lights the TEMP lamp so you don't even need the LED.

Ignition OFF
Ground Pin #3
LED + on Battery + terminal
LED - on Pin #1
Ignition ON

Now you should see the LED lit.  Slightly opening the throttle should make the LED go out.  If so, your TPS is within factory range."

[Laitch]

When did you last check the condition of the heat sink paste on the ignition amplifier? If it has deteriorated, it can cause power problems. The mating surfaces of both the ignition amplifier and its retaining plate (green arrows) should be clean, a thin coating of paste is applied to both of them then they are bolted together.  Here's a thread for reference.

[Filmcamera]

If the throttle position sensor is mis-adjusted it can affect performance.  Normally it messes up the idle along with it, but it's worth checking.

Do you know how to set the idle position on the throttle position sensor by grounding the pin on the diagnostic plug?   

Here's how you can do it.

http://www.largiader.com/articles/motronic.html

 "We can do a quick check of the TPS setting on Motronic 2.2 (and I think 2.1) using the 3 position diagnostic connector. I've tested this on my '96 R1100RT and it works.  I'll check my '93 K1100LT (MA 2.1) one of these days and let you know but I'm pretty sure it works the same and in addition, it lights the TEMP lamp so you don't even need the LED.

Ignition OFF
Ground Pin #3
LED + on Battery + terminal
LED - on Pin #1
Ignition ON

Now you should see the LED lit.  Slightly opening the throttle should make the LED go out.  If so, your TPS is within factory range."

Hello,


Yes I have done that, the last time was maybe 18 months ago but it was fine then.  I shall recheck it, good idea, thanks.

[Filmcamera]

When did you last check the condition of the heat sink paste on the ignition amplifier? If it has deteriorated, it can cause power problems. The mating surfaces of both the ignition amplifier and its retaining plate (green arrows) should be clean, a thin coating of paste is applied to both of them then they are bolted together.  Here's a thread for reference.

I replaced the heat sink paste two years ago so it should be good, but I will keep it in mind if other things do not fix the issue, thanks

[Filmcamera]

I spliced the side stand switch to remove that and replaced the fuel filter and the bike worked great.


Until it didn't and the old problems appeared again.


Then I finally found the issue (I hope)


One of the wires where it goes into the ignition amplifier connector was slightly lose.  That meant that sometimes, when going up hill the pin would lose connectivity and I would lose two cylinders.


I took me about two hours of painstaking wiggling of different wires and opening and revealing the loom in all it's glory to finally track that down.  That was Saturday.  On Sunday I did a 7 hour 275 kms ride over mountains and had no problems at all.


I am hoping it is really fixed at last!


Thanks for all the help and suggestions, I now at least also have a largely refreshed ignition system!

[Laitch]

I took me about two hours of painstaking wiggling of different wires and opening and revealing the loom in all it's glory to finally track that down.  That was Saturday.  On Sunday I did a 7 hour 275 kms ride over mountains and had no problems at all.

Thanks for the update and clear description of your treatment for this malady. 

[The Mighty Gryphon]