'75 R90/6 charging issues (new to the board)

[SteveD]

I haven't seen it here, but it probably needs to be written in the context of this thread, for other readers that don't know.....

The battery must be disconnected when removing/replacing the front cover, otherwise the diode board may be damaged.

To take that one step further, could the new diode board be dodgey?

[Red]

We have a winner. -Studying the wiring diagram further and exploring the possibility of a starter relay fault, I found that a previous owner had switched a black wire from the relay that goes into the headlight bucket and attaches to nothing with the blue wire that goes to the voltage regulator/stator. The light goes out and I now have 13.7 volts at the battery. Sure wish I had a color wiring diagram a couple days ago. PS: I re-fitted the old diode board and the old rotor for kicks and the gen light came back on. When i put the new diode board back on the problem was fixed again. So it turns out the diode board was bad all along as well as the wire mix up. Thank you all for the great assistance. Now it looks like I have a bent spoke and some notchy steering bearings to look after! Cheers!

[Airbear]

Good to hear Red.
Big thanks to the contributors for the diagnostic sequence. I've saved the entire thread to a Word doc and will print and carry it with me. One day I know it will be useful.

ps: Red, if you search the Archives you'll find some good info about the steering head bearing replacement. It can be done pretty easily with the assistance of some simple home-made tools. The bearings are inexpensive from your favourite bearing shop.

[Duane Ausherman]

It is fairly easy to replace the bearings, but it isn't so easy to realign the forks afterwards. Read and learn about this issue before you dive in.

[Ken in Oklahoma]

The bearings are inexpensive from your favourite bearing shop.

I dunno about that Airbear. When I replaced the bearings in my '91RT I was in Seattle, but I couldn't find the bearings in a local bearing shop. And I understand that all airhead steering head bearings are the same. Curiously I found the same part number in a area local shop, but at an extraordinarily hight price. I asked the person to please double check the price and he confirmed that it was indeed correct (I think somewhere around $200 each, give or take).

Max Headroom, who deals bearings, clued me in. Those same P/N bearings found in the local shop are very large bearings used in some kind of industrial application I suppose. I've probably got that confused, but if I do Max will likely see it and make the necessary corrections to my story.

Where I'm headed with all of this is that for me the bearings were only available at a BMW dealer. Fortunately the dealer had gotten a fresh order in and they were available (after driving end to end through Seattle during rush hour). The bearings I seem to remember as being a bit pricey, something like $40 each, give or take.

I also seem to remember from a previous thread that those bearings are unique to BMW, hence the higher than expected price.

I bought two sets, one to use and one to have in stock when I need them on another bike.



Ken

[Airbear]

Ken, I'm certain we discussed this very thing a while ago, 2008, back on the Ancient Phorum. **

My experience was that I took a sample to my nearest little sole-operator bearing shop and he was able to get them for me overnight. They cost $17.50 each.

** Don't worry about this, mate - some mornings I have trouble remembering my ... um ....

[Kurt in S.A.]

Anton lists the bearing number on his webpage:

http://largiader.com/parts/crossref.html

Snowbum also mentions the steering stem bearing number as:

"The steering head bearing is common type 32028, 28 x 52 x 16 mm. BMW has used this number on all the Airheads."

Kurt in S.A.

[Ken in Oklahoma]

Thanks Airbear and Kurt for the corrections. I'll try to get them into my long term memory. Better than that I'll copy and past the info and put it into my folder of BMW technical stuff.

Then the only trick will be to remember that I put something about steering head bearings in my BMW technical stuff folder.



Ken

[Ken in Oklahoma]

Thanks Airbear and Kurt for the corrections. I'll try to get them into my long term memory. Better than that I'll copy and paste the info and put it into my folder of BMW technical stuff.

Then the only trick will be to remember that I put something about steering head bearings in my BMW technical stuff folder.



Ken

[Airbear]

Well, you have made a good start there, Ken. Good luck with remembering whatever it was you were trying to remember. I was going to write that twice to cover your double post, but that would be silly.

Talking about keeping stuff in a folder, I've been having a think about putting all the info I have stored electronically over the years onto a memory stick and carrying that on the bike. Wouldn't be much use down a remote track unless I also had a notebook computer with me, but for a situation where I had access to a 'puter I could access all the stuff I've saved from websites, including PDF manuals and so on.