BMW K bikes (Bricks)

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1Back to top Go down    One black spark plug. on Mon May 05, 2014 10:01 pm

enzo

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Changed the spark plugs and one was completely black. The others were the normal light grey.
I than pulled the same cylinder plug again after 200 miles and again it is very black. Not oily but very dry and black.

This is a bike I have had for less than two weeks. 1985 K100RS with 29k on a working ODO. I know the miles are an unknown. No smoke at start up ever and bike seems to run fine. Any ideas?


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1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

2Back to top Go down    Re: One black spark plug. on Mon May 05, 2014 10:04 pm

RicK G

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It sounds to me that the injector may be sticking open. My first move would be to get the injectors serviced.


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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
    

3Back to top Go down    Re: One black spark plug. on Mon May 05, 2014 10:22 pm

kartooo

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is it #4 ?
the one that has the vacuum line going to the fuel pressure regulator.
if the membrane in there gets perforated it will suck fuel in by way of the vacuum line.
just like the old vacuum modulators on transmissions. when bad the engine would suck in trans fluid.


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85 k100rt current
04 vulcan 1500 classic sold
07 bonneville black sold
05 fjr1300 sold
04 r1150rt sold
91 k100lt sold
r80rt sold
85 K100 sold
    

4Back to top Go down    Re: One black spark plug. on Mon May 05, 2014 11:48 pm

enzo

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It's cylinder number two. Good info however!


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1985 BMW K100RS Alaska Blue
2012 KTM 500 XC-W
    

5Back to top Go down    Re: One black spark plug. on Mon May 05, 2014 11:55 pm

RicK G

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Try changing #1 and #2 plug about as it could be a bad plug.


__________________________________________________
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
    

6Back to top Go down    Re: One black spark plug. on Tue May 06, 2014 6:44 am

92KK 84WW Olaf


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When you fire it up from cold just check and see does the exhaust header heat up as fast onno 2cylinder. I had a similar issue on the LT, changed plugs and got a dud plug, after a second change all was fine.

If the exhaust is not heating up try swapping the plug leadsbetween 2 and 3 if you can.If it is heating up check out the injector but if not heating up check out that its actually getting a spark.


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1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 84,100 miles
    

7Back to top Go down    Re: One black spark plug. on Tue May 06, 2014 10:00 am

k75RT Keith

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If the plug swap fails, either upgrade to the new style injector and you can send your out to Mr. Injector in Idaho. Usually turns them around in a day or 2.

    

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