BMW K bikes (Bricks)


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1Back to top Go down   Ground battery cable Empty Ground battery cable Tue Nov 28, 2023 1:51 pm

lucki

lucki
Silver member
Silver member
Just finished a clutch spline lube job. Never been done spline okay 125000 km. I noticed the ground cable that goes to the housing near the gearshifter seemed very light. Any advantage to increasing the wire size?
Cheers

    

2Back to top Go down   Ground battery cable Empty Re: Ground battery cable Tue Nov 28, 2023 2:19 pm

Dai

Dai
Life time member
Life time member
Depends what you mean by 'light'. What's the diameter? Is it the OEM cable? To help matters, you can unscrew the cable from the gearbox and clean up the corrosion that's bound to be there.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

3Back to top Go down   Ground battery cable Empty Re: Ground battery cable Tue Nov 28, 2023 4:05 pm

Bricklayer

Bricklayer
Silver member
Silver member
When you loosen the bolt holding the cable to the transmission case one might here a "crack" sound, a definite sound of corrosion and need of some attention.

Now that we are somewhat on the topic of ground/earth cables, I just produced this video today for my YouTube repair/improv comedy channel. Laughing

https://anthonymrugacz.net/
    

4Back to top Go down   Ground battery cable Empty Re: Ground battery cable Tue Nov 28, 2023 4:51 pm

lucki

lucki
Silver member
Silver member
Some of past post suggest a second ground to the starter bolts. Also said early ks had light gauge ground wire. Mine is 87 built June 86 so I assume it is the light wire. No electrical issue yet but may replace with heavier gauge, can't hurt.
Like the 6mm wrench in the footpeg, will do.

    

5Back to top Go down   Ground battery cable Empty Re: Ground battery cable Wed Nov 29, 2023 3:18 am

Suzi Q

Suzi Q
Life time member
Life time member
I think the ground cable always seems a bit thin because the insulation on it isn't all that thick. The cable itself is 6.0mm sq. (per the handbook that came with early Ks) The cable on K's is good quality, much better than the stuff on later BMs. That said, only good can come of upgrading 30/40 year old wiring, even if it only results cleaning and remaking the connections.


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Sometimes I'm not really Suzi Quatro.
    

6Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 6:36 am

robmack

robmack
Life time member
Life time member
I replaced the ground cable on my bike with a heavier gauge one because I felt the OEM cable was too light a gauge.  The sum of all the current consumed by the electrical devices on the bike travel through that wire on the way back to the battery.  A larger diameter wire means less resistance, although we are talking milli-ohms difference, and less voltage drop with. greater available voltage to the bike's electrical devices.  There could be a significant return current, in the tens of amps..

http://k75retro.blogspot.ca/
    

7Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 7:01 am

charlie99

charlie99
VIP
VIP
robmack wrote:I replaced the ground cable on my bike with a heavier gauge one because I felt the OEM cable was too light a gauge.  The sum of all the current consumed by the electrical devices on the bike travel through that wire on the way back to the battery.  A larger diameter wire means less resistance, although we are talking milli-ohms difference, and less voltage drop with. greater available voltage to the bike's electrical devices.  There could be a significant return current, in the tens of amps..
Yes agree rob
The start relay is rated at 80 odd amps....given this and knowing there is likely another 8 amps in ignition and other demands ...6 mm seems a bit short of the number reguired to keep available current without too much voltage drop...in awkward situations
..


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
1987 k100rs ########   "Red"  - (red sports rs TWB style )
1989 K100rt #009637   "Black Betty"  (naked rt ala Nigel , now sporting an rs main fairing )
    

8Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 9:06 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
I replaced the ground wire on several of my bricks.  The reason was to add an emergency disconnect.

When replacing that wire, go to a place that sells wire for marine applications, a boat supply or chandlery.  Get marine grade wire, the good stuff will have thinner conductors and better, thinner insulation that will make the wire a lot more flexible, and make sure the conductors are tinned copper to prevent corrosion.  It's more expensive, but you are only getting a couple feet.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

9Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 1:09 pm

firstle

firstle
Life time member
Life time member
the ex service model i have here has the ground wire doubled and a larger flat strap type ground from the frame to the bottom yoke ? not seen that one before  Crying or Very sad

    

10Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 3:51 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
On my various K bikes I've generally cleaned up the connections then made up a heavier gauge wire, and added a minor second one to a solid earth point on the engine, or the starter body hold-down screws.


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"A long ride is the answer to a question you will soon forget!" ~ Anonymous
1977 R75/7-100, '93 K11/K12 Big Block, '93 K1100RS, '95 R100 Mystic, '96 K1100RS, 2 x '98 K1200RS, '06 K1200R & '09 K1300GT
    

11Back to top Go down   Ground battery cable Empty Re: Ground battery cable Thu Nov 30, 2023 5:16 pm

Dai

Dai
Life time member
Life time member
Then, of course, there's me. When I make a complete new loom I earth everything back to the battery through the loom and don't pick up the frame. I make a nice new battery cable too. Result? If the battery earth is screwed nothing goes through the main loom - no start but no meltdown either.

Awkward git. Of course I am Razz


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

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