ST1100 Mystery From The Past

Joined
Feb 29, 2016
Messages
195
Location
New York
It has been 17 years since I sold my 92 ST1100. I had a problem with it which I will relate presently. Although I was able after a while to effect a remedy of sorts, I never discovered what was actually wrong with it. I wonder if anyone here could enlighten me? Carefully follow in detail the following sequence of events before rendering a verdict.

One day when the bike had about 50k miles on it, I pulled in the clutch put it in gear and the engine died. The kickstand was up but I moved it up and down a couple of times before making sure it was fully in the up position. Again the engine died when I put the bike in first gear. (or second gear!) After a few more attempts it finally went into gear without killing the engine.

Id had the same problem with my old airhead which I fixed by shorting the two sidestand switch wires together. I figured I was experiencing the same problem with the ST1100 and planned to effect the same repair. But the bike didnt exhibit the problem again for quite some time and I never got around it to.

It did it again a few times again years later, each time going into gear without killing the engine after a few minutes of trying. Then one day it flat out refused to go into gear without killing the engine. I had no choice now but to short the two wires together and proceeded to do so. Imagine my surprise when I found not two but three wires going to the sidestand switch! I got out my wiring diagram and puzzled and puzzled over it, trying to figure out which wires to short together. I never did figure it out and wisely refrained from just cutting and stripping the wires and shorting them together willy nilly. Perhaps this can be done and someone knows how?

This resulted in a week of not going for a ride while I puzzled. In the meantime I priced a new sidestand switch, $50. The dealer was 50 miles away so I kept trying to effect a repair. Eventually I hit on one.

I removed the 8mm bolt holding the switch to the sidestand and observed the tang on the switch that goes into a hole on the sidestand. I broke the tang off and slightly re positioned the now tangless switch little by little until I found a position where it would not kill the engine when put into gear. The 8mm bolt when tightened held the adjustment formally secured by the tang.

In a year I never had another problem with it. I did buy a new switch on a trip into the city but didnt install it. Time passed. While prepping the bike for a long trip I thought to myself "I better install that new sidestand switch before leaving." and did so. The switch seemed to work perfectly.

A few days later I was on a local three lane freeway going 75 mph in bumper to bumper traffic in the left most lane. The engine suddenly quit! :eek:That blankety blank new sidestand switch! :mad:Some how I maneuvered to the right side of the road and the shoulder without incident. (I dont like to think about that!) Fortunately I had the old modified switch with me and soon I was on my way. Never had another problem with the bike until I sold it. I told the story to the soon befuddled new owner but I dont think he ever fully comprehended what I was try to explain.

Does anyone out there have any idea what the heck was going on? I have to assume the problem wasnt in the switch.

But where was it? Inquiring minds want to know!:confused:





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t1100
 

Uncle Phil

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698
It would have to be the sidestand circuit since that was what you were 'operating' on. I would've trace the wires to their destination to see if I could find anything. I'd probably also looked at the clutch switch just for giggles.
 

John OoSTerhuis

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May 10, 2005
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Bettendorf, Iowa
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1991 SSMST1100
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1058
I agree with Phil. There was (still is...!?!?) an intermittent break in the side stand circuit. The ignition module senses that the circuit that is normally completed to ground when the side stand is up is broken/separated. Bypassing the switch by joining the green-white lead with the green lead would normally be the field expedient repair to get you home, or by breaking the tab on the old switch as you did. Then being careful to insure the side stand was up before pulling away. However, you report a new switch didn't fix the problem so the problem must be in the wiring between the ignition module and the switch, or between the switch and the ground. If so... why didn't it reoccur...? Hmmmmm....

The yellow-black lead at the switch turns on the side stand light in the dash when the side stand is down, completing that circuit to ground.

Edit: colored wiring diagrams that should help anyone troubleshooting the engine start/run safety interlock system/circuits: http://www.st-riders.net/index.php?topic=3908

So... you sold the bike to the new owner advising that the side stand safety switch (and light) didn't work and to always check that the side stand was up before riding away...?

John
 
Last edited:
OP
OP
Joined
Feb 29, 2016
Messages
195
Location
New York
So... you sold the bike to the new owner advising that the side stand safety switch (and light) didn't work and to always check that the side stand was up before riding away...?

John
Absolutely! I tried to explain what happened and what WOULD happen if he just replaced the switch with a new one...but got a really blank look.

We all have our blind spots....this guy just wasnt mechanically all there!

Your post has given me food for thought about the problem...thanks.
 

kiltman

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Apr 27, 2013
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8826
I spent an hour on the side of the road on a cold October afternoon last year trying to resolve a similar issue. I did the yellow to each green separately before consulting a wiring diagram and discovered what John had outlined the two green wires needed to be jumped. I'm on sidestand switch #3, hopefully that will be it.
 
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