• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

Where do the + and - battery cables connect to the bike?

K

khoury

Guest
So I forgot the golden rule and pulled the battery without first noting which battery cable connected to which terminal. Can anyone definitively tell me which goes where? It a 1975 R90/6. Thank you.

A bit too anxious to ride-aron
 
Negative on the starboard (Right) side. The negative cable connects to a very small and easy to strip "breather" bolt on the transmission.

The positive cable connects to the solenoid on the starter. The positive terminal on the battery will be on the port (Left) side of the bike. The positive cable is about 2.5 times the length of the negative cable.

Do you have a Clymer's manual? A great reference to have.
 
So I forgot the golden rule and pulled the battery without first noting which battery cable connected to which terminal. Can anyone definitively tell me which goes where? It a 1975 R90/6. Thank you.

A bit too anxious to ride-aron

Don't feel bad. The last time I changed my battery I did take note. By the time I had the box open I forgot what was what.
 
You might want to take this opportunity to ground your battery to something other than that all-too-easy- to- strip breather bolt on the transmission. Using the existing ground cable limits your options, but getting a slightly longer cable increases the number and accessibility of places to ground the battery.
 
You might want to take this opportunity to ground your battery to something other than that all-too-easy- to- strip breather bolt on the transmission. Using the existing ground cable limits your options, but getting a slightly longer cable increases the number and accessibility of places to ground the battery.

Where do you ground your battery?
 
I actually haven't taken the opportunity yet, but when I last changed my battery, I decided I would find a different ground spot the next time the bike gets a new battery. I could feel the metal give a little bit, and I knew it was doomed.
 
I've seen /6 transmissions with the casting cracked from over exerting that bolt. DAMHIK. Twice.
If you are experimenting with grounding the battery somewhere else, please heed the advice that I found in the DYNA III installation document. Don't count on grounding to the frame as the most critical components for ignition are grounded to the motor. Theoretically, grounding the frame will suffice but if there is any cause for resistance between the frame and engine (corrosion, loose bolts, etc.) you may have some magical hard-to-diagnose problems. Never argue with an electron.
 
I was looking at a guys /7 tonight and I followed the neg cable up to the right side gas tank mount.

Odd...

Odd indeed. :scratch

Just think, taking the tank off could proovide extra excitement. Pull the fuel lines exposing
that annoying little dribs of gasoline...then taking the thumbscrews off and pulling the neg cable
....sparky, sparky, boom, boom.

Say....arent you an explosives kinda guy? :rocker

The motor makes the best ground IMO.
 
Well, doncha know. My AIRMAIL came today, and the first letter to Oak is the Stripped Ground Bolt. He explains the necessity of the hole in the bolt into the transmission, and offers one solution for a stripped bolt as buying another screw, drilling a hole in it, then tap the transmissin hole, inserting a larger bolt..........
OR - "You may opt to hook up the battery ground elsewhere. I have used the frame lug hidden by the right side cover. Undo the cover, scrape the paint away, and bolt the battery negative there, then coat it wth grease."
Others have bought a longer ground cable to connect at another convenient spot. The critical issue is making and keeping good ground contact. Ease of disconnect and reconnect for maintainence is also a factor.
But the gas tank mount? Wouldn't be my first choice. Nor my last, unless it was the last.
 
Back
Top