BMW K bikes (Bricks)

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1Back to top Go down    Jumping fuel and temp gauges on Fri Apr 28, 2017 3:37 pm

club_c

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I have noticed the fuel and temperature gauges on my 88 RS jump and flicker a lot while riding. Remember this bike was in storage for 5 years and I've just recently got it running. Is this typical (I haven't had a K with these gauges before) or is there a connection point I should be considering?


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"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

2Back to top Go down    Re: Jumping fuel and temp gauges on Fri Apr 28, 2017 9:07 pm

RicK G

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With both behaving the same way I would be looking at an earth connection (brown) probably under the tank or the common power connection (green/black) from fuse #1


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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    Same Problem Almost on Mon May 08, 2017 8:23 pm

TurboBrick

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I have an issue with my temperature gauge jumping around. The bike sat for about 8 years after it had been ran over in a garage Rolling Eyes . The issue is it will get to about (1/2) (3/4) mark and start fidgeting around. It concerns me the bike is getting this hot. I will say when it does reach the red the temp light never comes on and the fan never comes on. Any ideas?

    

4Back to top Go down    Re: Jumping fuel and temp gauges on Mon May 08, 2017 9:10 pm

duck

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Your temp gauge is not connected to the ignition system.

The temp relay for the ignition system is connected to a sensor in the aluminum tube coming off the top front of the cylinder head. That is what controls your fan and the red light in the cluster.

The temp gauge has a separate temp sensor at the bottom of the water pump and only feeds that gauge.

I'd check the gauge wiring harness connector under the tank and then the ground to that connector.

It's very hard to overheat a K bike.

First the fan kicks in.

If the fan isn't working and the bike gets too hot then the warning light in the cluster comes on.

If you ignore that and the bike gets even warmer then the radiator cap under the right front of the tank will blow. (Just like a car does.)

If you ignore that then you will harm the engine.


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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
http://www.ClassicKBikes.com
    

5Back to top Go down    Re: Jumping fuel and temp gauges on Mon May 08, 2017 9:53 pm

TurboBrick

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@duck wrote:Your temp gauge is not connected to the ignition system.

The temp relay for the ignition system is connected to a sensor in the aluminum tube coming off the top front of the cylinder head. That is what controls your fan and the red light in the cluster.

The temp gauge has a separate temp sensor at the bottom of the water pump and only feeds that gauge.

I'd check the gauge wiring harness connector under the tank and then the ground to that connector.

It's very hard to overheat a K bike.

First the fan kicks in.

If the fan isn't working and the bike gets too hot then the warning light in the cluster comes on.

If you ignore that and the bike gets even warmer then the radiator cap under the right front of the tank will blow. (Just like a car does.)

If you ignore that then you will harm the engine.
That's good to hear. Thanks for the peace of mind!

    

6Back to top Go down    Flickering Temp Gauge on Wed Aug 02, 2017 4:24 pm

blacknails


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Hi duck.

I have an 89 K100RS with 70K on the clock which has the same problem. Smile
The flickering only occurs once you get the bike warm and exceed 3500rpm. I have been told from this forum to look under the right hand side of the fuel tank for some old blade type connectors which may have come loose. Mine were but this did not cure the problem. To date I have not cured it but as the bike is 28 years young you can expect some sulking. Crying or Very sad
I am working my way through the loom now looking for dry joints.

Regards

Blacknails

    

7Back to top Go down    FIXED on Wed Aug 02, 2017 4:42 pm

TurboBrick

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I found the problem with my gauge. The after market header for the turbo on my bike was getting the temp sensor too hot when the bike wasn't moving. After a quick wrap with some heat tape all was normal!

    

8Back to top Go down    Re: Jumping fuel and temp gauges on Wed Aug 02, 2017 8:53 pm

club_c

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and my issue is a dirty sending unit. I saw a post once about opening up the unit and cleaning connections etc. Of course I can't find it now. Does anyone remember that one?


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"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

9Back to top Go down    88 K100 RS Jumping Temp Gauge. on Wed Aug 09, 2017 4:32 pm

blacknails


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Good Evening all.

Found the problem to the jumping temp gauge. Looked at the two sender units below the water pump. The lower one is the temp gauge sender unit and the connection was loose and dirty. You will have to remove the rubber boot to discover this. However now all is well with the K100.
Thanks to all for pointing me in the right direction.

Regards

Blacknails

    

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