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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: john11668 on March 06, 2016, 07:04:52 AM
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Having just fixed one problem another appears ! Aint that just Typical
Just secured a front flasher and sorted a wiring issue which was probably the cause of fuse popping.
Now I find the speedo erratic. Dropping back to no reading , then maybe back up to 25 mph as I am riding along.
I will check connections but I just want to understand how it works.
Am I right the the sensor is effectively a pulse generator and the head contains a counter ??
Before I go digging I also want to have a look at the fuel lights, of which the red one stays on (I know you all think i am too fussy).
I was going to start to delve into checking probes for resistance, but some research in advance tells me my bike should have a float switch.
I know that the cluster has been changed , (and have reason to suspect the previous owner was no expert ) so just wondering if there could be other issues in there.
Having just had a bit of an intrusive hernia repair job I will be grounded from riding for a couple of weeks, so might as well make good use of the time
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Am I right the the sensor is effectively a pulse generator and the head contains a counter ??
I'm assuming your K100 is stock. The speed sensor is located on the top of the final drive. It is a variable reluctance (VR) sensor that detects the gear rotating inside the drive. It outputs a low voltage (~0.5V) sine wave that has six peaks per rear wheel revolution. The signal is fed into the instrument cluster where the circuitry inside amplifies the signal and then counts the pulses to indicate the speed.
There is a connector under the right battery cover, at the back of the cluster and within the cluster.Typically, poor connections somewhere in the path causes the signal to degrade in quality and the speedo to respond erratically. Your investigation should concentrate on finding the poor connection and eliminating it, by making sure all connections are clean and secure.
- remove the speed sensor and make sure it is clean (sometime iron filings gather on it)
- locate the connection under the right battery cover and clean/reseat it
- reseat the instrument cluster connector a few times to help remove any corrosion
- if these actions fail to clear up the problem, you will need to open the gauge cluster to locate the amplifier card and clean its contacts
Before I go digging I also want to have a look at the fuel lights, of which the red one stays on (I know you all think i am too fussy).
I was going to start to delve into checking probes for resistance, but some research in advance tells me my bike should have a float switch.
Your 86 has a float sensor inside the tank that has a variable resistor to indicate fuel level and a switch to turn on the low fuel light. If the light is always on, then somehow that circuit is shorting to ground. The low fuel light circuit has a connection at the tank, and at the instrument cluster. You will need to empty the tank of gas to service the sensor because it will need to be removed.
- separate the tank connector and test resistance between the white wire and brown wire on the tank-side connector. It should be open circuit with the float raised, and closed circuit with the float depressed. If it always shows closed circuit, the problem lies in the sensor.
- Remove the connector from the rear of the instrument cluster. Test for resistance between the white wire on the harness side of the tank connector and ground. If it always shows closed circuit, the problem lies in the wiring harness somewhere.
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Before I go digging I also want to have a look at the fuel lights, of which the red one stays on (I know you all think i am too fussy).
I don't think you're too fussy, john. A person who gets into the habit of ignoring red warning lights probably will ride into a world of hurt sometime or other.
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Your 86 has a float sensor inside the tank that has a variable resistor to indicate fuel level and a switch to turn on the low fuel light. If the light is always on, then somehow that circuit is shorting to ground.
If the float on the end of the gauge stem is hollow, it could have developed a pinhole leak, filled with fuel and then sunk to switch on the light. If the stem can be lifted and the light shuts off, there's a clue. This malady is probably not as likely as the connection problems explained by Robert.
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Before I go digging I also want to have a look at the fuel lights, of which the red one stays on (I know you all think i am too fussy).
Having just had a bit of an intrusive hernia repair job I will be grounded from riding for a couple of weeks, so might as well make good use of the time
Best wishes for a quick recovery on your repair job.
No, you aren't too fussy. There is nothing worse than riding at night with that low fuel light glaring up at you.
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Spose I could take out the bulb and bung a gallon of fuel in the luggage box but there is something good about fixing a problem :bmwsmile
Thanks for the pointers guys. Wiil get used to the foilbles of these machines. Last bike I had used a spinning cable drive.
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greetings...
yes there is... riding at night with the low fuel and low weed lights on... it may be unsurvivorable...
j o
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Fuel level light now gone out .
I had a general all around check of plugs and connectors and light went out . Should it self test with the ignition and then go out , or do i have to wait until the level drops to test it ?
Speedo sensor and connections checked , but speedo still reading low . It responds to road speed but reads about 25 when doing 60.
Next step please ??
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I have followed advice and cleaned a bunch of mucky connectors in the cluster but on reassembly found pin 13 loose (only held in place by the rubber mat that surrounds all the pins. )
Now on checking I find it is a ground pin, but so is no. 18 ! http://www.motobrick.com/index.php/topic,8017.msg59337.html#msg59337
Will one sound pin suffice or do I need to get 13 re- soldered??
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You need both grounds. Pin 13 is ground for instrument functions like tach, speedo, clock. Pin 18 is ground for instrument lights.
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With a bit of perseverance last night I managed to get it soldered .
There is now continuity from 13 to 18 so they must be common rather than independent grounds .
Biggest problem was preventing solder bridging to 14 but I think I have succeeded ( no continuity) . Will soon see
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Took the bike out for a run on Saturday and all seems fine . Speedo now reading fine . Thanks for all the tips .
Now I will bung a gallon in the luggage box and ride till the red light comes on ( or not as the case may be )