BMW K bikes (Bricks)

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1Back to top Go down   Tacho needle wavering Empty Tacho needle wavering on Fri Apr 03, 2020 11:36 pm

Tom KSR

Tom KSR
Life time member
Life time member
G'day All,
My 1986 K100RT  (ex police) also known as the Goulburn bike, has developed a problem with the tacho needle fluctuating widely at a constant speed.
So far I have checked that the two long plugs into the cluster are seated properly and that there is continuity in the red/blue wire from the coil to the plug at the cluster.
The other thing may be that the needle is not seated correctly on its pin.
Any thoughts on thiss little issue would very much appreciated.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

2Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Fri Apr 03, 2020 11:43 pm

RicK G

RicK G
VIP
VIP
Pull the sensor out and clean it. It's in the rear drive you need a 4mm Allen key and lever it gently out then check the surface it will probably have some iron residue build up on the face. it comes from normal wear on the gears


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

3Back to top Go down   Tacho needle wavering Empty Tacho Needle Wavering on Sat Apr 04, 2020 12:32 am

Tom KSR

Tom KSR
Life time member
Life time member
Thanks Rick, the speedo needle was also wavering and I have cleaned the sensor which was pretty grotty.
The Tacho needle is the problem. There is continuity for the red/blue wire from coil to plug and continuity for the earth wires from plug to frame.
Before I delve any further I'll for any other replies.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

4Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Sat Apr 04, 2020 12:41 am

MartinW

MartinW
Life time member
Life time member
The tacho picks it's signal from one of the coils. It could be a faulty/dirty connection.
Regards Martin.


__________________________________________________
K75s Hybrid
    

5Back to top Go down   Tacho needle wavering Empty Tacho Needle Wavering on Sat Apr 04, 2020 1:05 am

Tom KSR

Tom KSR
Life time member
Life time member
Thanks Martin,
The coils are new and the red/blue wire ( the signal sender from the coil) connection is tight and clean.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

6Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Sat Apr 04, 2020 1:40 am

duck

duck
Life time member
Life time member
If the needle gets loose it will fall off completely so that is not your issue.

Connection where the connector on the back of the cluster connects to the pin?  Make sure that the female terminal in the connector has not been pushed in.

Also try to trace the tach wire inside the cluster to see if you can find a flaky connection there.


__________________________________________________
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 (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

7Back to top Go down   Tacho needle wavering Empty Tacho Needle Wavering on Sat Apr 04, 2020 1:54 am

Tom KSR

Tom KSR
Life time member
Life time member
Thanks Duck,
Opening the cluster is my next step. I'll keep you posted. 
Thank you all for your input.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

8Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Sat Apr 04, 2020 5:57 am

Dai

Dai
Life time member
Life time member
The other thing that I have seen is the wee coil spring wrapped all out of shape. A gentle dig with a jeweller's screwdriver sorted that and stopped the needle bounce (speedo, as it happens).


__________________________________________________
'83 K100 upgraded to K100RS spec, '87 K100RT
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California
    

9Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Sat Apr 04, 2020 11:21 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Is there any misfiring?  A faulty Hall Sensor signal could be causing the problem.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

10Back to top Go down   Tacho needle wavering Empty Tacho Needle Wavering on Sat Apr 04, 2020 6:02 pm

Tom KSR

Tom KSR
Life time member
Life time member
Thanks Dai and Point-Seven-Five,,
There is no misfiring. The engine is running as sweet as a nut, just ask Waz.
I'll be delving into the cluster today and check out Dai's wee coil spring. I'll keep you posted.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

11Back to top Go down   Tacho needle wavering Empty Re: Tacho needle wavering on Sat Apr 04, 2020 6:21 pm

MartinW

MartinW
Life time member
Life time member
Does the fluctuating ever settle down or is it constant.
Regards Martin.


__________________________________________________
K75s Hybrid
    

12Back to top Go down   Tacho needle wavering Empty Tacho Needle Wavering on Sat Apr 04, 2020 7:13 pm

Tom KSR

Tom KSR
Life time member
Life time member
Hi Martin, the fluctuation is pretty constant. Even at idle the needle moves around a lot more that normal.
Cheers
Tom


__________________________________________________
1986 K100RT Ex Police (Slightly modified)
2010 Suzuku DL650 V Strom
1992 R100R
    

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