BMW K bikes (Bricks)


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1Back to top Go down    Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 5:21 pm

53cr3t5quirr31

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Okay so I have a 1987 k100rs I have turned into a cafe racer. The bike has only 30k miles and I am having a load of issues. Went to start the bike today and nothing... I click the starter it does a quick jolt of the starter then cuts out.. immediately I think it's the hall sensor.. nope hall sensor checks out fine... all of my fuses are good.. all connections and electric grease on them.. as I was trying to get it to start the ignition coils started to buzz almost as if they got stuck or something.. I unplug the coils from the harness and bam! The bike constantly turns over but no fuel pump.. strange... I check the pump with a 12v jumper it works I then go to the under tank connection and I am getting 8volts with the starter depressed and it jumps to 10volts for 1.5 seconds after starter is let go... changed out FI relay.. nothing.. cleaned the starter winding and brushes.. nothing... swapped the load shed and light relay and the light still works.. only 8-9volts at number 6 fuse.. their is continuity from the computer to the FI relay but it is always at 0volts and does not carry 12volts with the ignition on.. do i need a new computer?? Anything I'm missing? Sorry for the long post I wanted to be thorough

    

2Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 5:55 pm

53cr3t5quirr31

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Edit*** just to clarify. With the kill switch in the run position and the key in the on position their is no 12v from pin #7 to the FI relay and when i press the starter their is not change in line voltage (should be +12volts when when key onand grounded when starter is engaged) let me know if I'm wrong thanks again!!!

    

3Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 6:07 pm

Laitch

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@53cr3t5quirr31 wrote:Edit*** just to clarify. With the kill switch in the run position and the key in the on position their is no 12v from pin #7 . . .
Pin #7 of the ignition control unit, pin #7 of the fuel injection control unit or some other pin #7?


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1995 K75T 68,000 miles
    

4Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 6:09 pm

53cr3t5quirr31

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Pin #7 of the ignition control unit

    

5Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 7:36 pm

53cr3t5quirr31

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Okay guys update****
I checked the wrong pin :/ I have now checked the correct pin #7 (not #2 as previously) and I am getting 8.8 volts with all the switches in the on position... when I go to crank the bike it drops down to 6 volts...
Also when I plug the coils back into the harness it's still only blips the starter before cutting out...
Dead CDI??? What's your thoughts?

    

6Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 8:01 pm

Laitch

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@53cr3t5quirr31 wrote: What's your thoughts?
What is the resting voltage of your battery right now?


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1995 K75T 68,000 miles
    

7Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 8:02 pm

53cr3t5quirr31

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12.6 volts

    

8Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Tue Sep 05, 2017 8:32 pm

53cr3t5quirr31

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*update
I just checked pin #10 at the ICU and I only have 9.4 volts

    

9Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 6:55 am

Overkill

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Sounds like a bad battery to me.

    

10Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 8:46 am

Point-Seven-five

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12.6V sounds like a weak battery/one that won't hold a charge.


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Present:
1994 K75RT
1994 K75S
1992 K100RS

Past:
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

11Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 2:27 pm

53cr3t5quirr31

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I'm running it off a large jump pack so I don't bleed down my brand new yuasa. All other fuses have 12 volts except fuse #6 it has around 8-9

    

12Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 9:20 pm

RicK G

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Firstly I would recommend replacing all the fuses. They get some internal corrosion and will fail when they look OK.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

13Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 9:26 pm

53cr3t5quirr31

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Already did that every fuse is brand new less than a week old

    

14Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 9:35 pm

RicK G

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The next step is to systematically go back along the wiring path and check voltage at each junction. My first place to suspect is the blue green wire at the ignition switch then the kill switch Green/yellow wire. I will say that a bad connection is responsible for the voltage drop.
The ICU and ECU will only work if the voltage is over a predetermined voltage of (I think) 9.5Volts, but it is in the area of the voltage you are finding.



Last edited by RicK G on Thu Sep 07, 2017 9:55 am; edited 1 time in total (Reason for editing : Duck was getting picky yeah it was green so sue me LOL)


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

15Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Wed Sep 06, 2017 9:40 pm

53cr3t5quirr31

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Okay I'll check for breaks in the wire. I believe the CDI is powered on because it triggered the FI relay and that is controlled by the CDI
Will report back

    

16Back to top Go down    Re: Please help! Maybe bad CDI or other?? on Thu Sep 07, 2017 8:56 am

duck

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@RicK G wrote:blue wire at the ignition switch

What blue wire?

Every ignition switch I've seen only has:
Red
Green
Gray
Gray/Blue


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Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S
14 Yamaha WR250R
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