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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: tjstoltz on August 24, 2019, 04:58:05 PM

Title: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 04:58:05 PM
I've got an 86 K100RS that's been running really poorly recently and I've made the problem worse. I put a jumper wire between the two contacts of the coolant temperature sensor plug and tried to start the bike. Now it won't turn over at all. The starter relay clicks whenever I turn the key even if I don't press the starter button. The tail light turns on a the first click of the ignition switch and turns off again at the second.

Anyone know what I've broken here and how I go about fixing it?
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 05:05:57 PM
Anyone know what I've broken here and how I go about fixing it?
Welcome. Check all the fuses, tighten the battery ground strap attached to the transmission, check the battery post clamps for tightness, eat a couple of cider donuts then report back.
Title: Re: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 05:08:06 PM
Fuses are all good as are the battery connections both positive and negative.
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 05:14:06 PM
Fuses are all good as are the battery connections both positive and negative.
Now tell us how long you've had the moto, how many miles are on it, whether it has been modified, how many miles you've ridden on it and what else you've done to it. Post a photo of it too. Use the Attachments and other options feature. You won't see the photo until after you make the post.
Title: Re: I did a stupid thing and I need help now
Post by: johnny on August 24, 2019, 06:34:46 PM
greetings...

we were discussing this at the secret cappuccino craftsmen and dumpsters  board...

are you sure it was the coolant temperature sensor plug and notts the hell effect sensor plug...

i calling fore pin... butts reserved untill i see photos of this biuld...

j o
Title: Re: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 06:45:28 PM
Besides the fact that it's a different wiring harness, the hall effect sensor has a 5-pin connector and the CTS had 2 pin Bosch-specific connector. I'm sure it wasn't the hall effect sensor
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 06:52:52 PM
Besides the fact that . . .
It's probably understandable that when somebody writes "I did a stupid thing", others might wonder about the solitariness of that sort of thing.

Anyway, you haven't disclosed anything about this moto to give us an idea of what you might be up against, except that it had a stupid thing done to it. Please fill us in.
Title: Re: I did a stupid thing and I need help now
Post by: johnny on August 24, 2019, 07:03:08 PM
greetings...

does your headlight low beam and high beam illuminate when you turn on the key...

j o

Title: Re: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 07:26:58 PM
It's probably understandable that when somebody writes "I did a stupid thing", others might wonder about the solitariness of that sort of thing.

Anyway, you haven't disclosed anything about this moto to give us an idea of what you might be up against, except that it had a stupid thing done to it. Please fill us in.

That's fair. I'll give you that. Considering I did a dumb things it's 100% fair to assume I also did other dumb things.

It's stock. I've had it for about 4 years. Got it as a basket case and have been working on it. I had it running last summer and put it away for the winter. It's been running poorly or not running at all since then. It's got about 50k.

The headlight turns on at the first click of the key and turns off at the second. The load she'd relay engages when the key is turned on fully whether or not the starter button is pressed.
Title: Re: I did a stupid thing and I need help now
Post by: johnny on August 24, 2019, 07:55:43 PM
greetings...

i donts believe in coinscidence so i calling battery and fore pin... butts reserved untill i sees photos of this biuld...

j o
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 08:04:52 PM
I don't believe the coolant temperature sensor stupid thing has any part in this, except as a harbinger of stupid things to come, and none of us is likely to have total immunity from those.

As j o has hinted, what's the resting voltage of the battery right now?

Title: Re: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 08:07:48 PM
My multimeter is showing 12.79 volts.

I would be really surprised if the coolant sensor had nothing to do with it though, but I've wrong about bigger things before. It was turning over before that and now it's not, so. Correlation != causation but context is still important.
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 08:28:53 PM
I would be really surprised if the coolant sensor had nothing to do with it though . . .
Explain why you'd be surprised.
Title: Re: I did a stupid thing and I need help now
Post by: tjstoltz on August 24, 2019, 08:44:58 PM
Explain why you'd be surprised.

Before I did this the engine was turning over and now it's not.
Title: Re: I did a stupid thing and I need help now
Post by: Scott_ on August 24, 2019, 09:00:04 PM
what is the battery reading when you turn the key to the 2nd click.(when you say the lights go off)
There must be enough current available to engage the start relay and load shed relay but not enough to engage the starter.
Sounds like something is shorted out in the start circuit, and/or a bad battery.
Title: Re: I did a stupid thing and I need help now
Post by: Laitch on August 24, 2019, 09:02:07 PM
Before I did this the engine was turning over and now it's not.
Correlation does not imply causation—especially on a semi-clapped–out relic motorcycle. What was the idea behind jumping those terminals?
Title: Re: I did a stupid thing and I need help now
Post by: E30_Crazy on August 24, 2019, 11:09:39 PM
A quick elimination to a few different common problems, is to check for 12V at the starter, with the starter button pressed. If theres is 12V, it will be the starter/something inside not working. If no 12V, then something between (and including) the battery, and the starter will be the culprit.

Can you hear/feel the starter solenoid closing when you turn the key on? Sounds like your load shed is working as if trying to start. Your starter relay may have welded shut (and you have a bad battery), or can't make contact to begin with.

Assuming it's not the starter solenoid, double check the contacts and wiring to the starter itself for proper electron flow facilitation.

Next, I would be examining the insides of the starter, cleaning and checking the brushes, and condition of other components. You could try rolling the bike backwards and popping the clutch in 3rd gear, to backspin the starter, but that may not reveal much, let alone cure the problem (more of a quick diagnostic and/or "get me home" technique).

Of course, these are all mute points if the battery isn't holding voltage when the key is on. Bad battery, dead cell(s), etc may be a causation.

A bit more of a reach (after examining the battery) would be the starter button. The contacts may be corroded beyond the ability to carry the power to the rest of the start circuit.

Post #10 here (http://"http://www.k100-forum.com/t12767-sudden-no-start-with-starter-button-where-to-check-next") may be a little more methodic than my sporadic memory of tests above (along with several other suggestions).