R90S weight reduction

[srankin]

Thank you, LOL, I am in less pain when riding than when walking or sitting, go figure? St.

[cbclemmens]

Sri;
I tried a lithium battery on my R75/5 and it took down my entire charging system. They are not compatible with analog charging systems. I STRONGLY caution you to check out your charging system before you install a lithium battery. If you put an oscilloscope on the output of the regulator (not connected to the battery) an analog system will show 13-14 volts with spikes down to zero (at the frequency of the alternator). A lithium battery will over draw on this system and take it down.
Craig

[sriman]

Point taken, Craig. I intend to replace the charging system with a newer one that is specifically made for a lithium battery. I think Euro Moto Electric makes such a system.

Sri

[srankin]

LOL, they don't make it but they do sell it.

I have seen in their catalog the system you are talking about. I am going to give a positive shill for EME, Norm and the people are VERY good to deal with. Of all the companies to buy the system from I would choose either theirs, Boxer two valve or Motorrad Electrik. St.

[Bluethumb]

Taking weight off of a R90S is difficult, as they are and particularly when they were built they are pretty light for their class. One way to drop weight and not lose any of the S stuff, if you could afford it would be to replace the wire spoke wheels with lighter mag wheels, store the wire wheels. Might be hard to find but I imagine a pair could be found. Lighter weight and less rotation mass. A lithium battery would drop a significant amount of weight and weight that is fairly high. I have no experience with lithium batteries, have read horror stories as well as success stories. I imagine there’s plenty of information about how to do it right out there courtesy of the web.

I wonder if you thought about lowering it? I don’t know if the height of the seat is a problem for you. I know for myself having both feet flat helps my confidence. My other bike I can’t, I have to lean to one side or the other at a stop, typically the left foot down. As I get older I get a little less confident on that bike and I’m planning on getting the seat cut down a little.

[sriman]

I have considered lowering the seat and have decided to replace the rear shocks with shorter YSS ones made for the R65 and also lowering the front end with parts from Oshmo. I wish I could find another seat that is lower and that I won't have any hesitation narrowing the front. That way I can store the original for someday when I sell the bike. I have not considered lighter mag wheels but that's something I will pursue. Happy to hear from anyone out there with just that!

Thanks.
Sri

[bmwsog]

I have owned two of these 900s: a 1974 and 1975. Still own the 1975.
Consider posting your R-90S in the member bike sale section of this site
along with the ON News, Airhead Site, and other motorcycle online or published versions.
This may be , with patience-the best possible answer.

I am a senior disabled rider, and still manage these BMW motorcycles:

1951 R 51/3--1962 R 69 S--75 R 90 S--1986 R 80 "S

Bon chance!

[sriman]

Hi BMWSOG,

I truly appreciate your sentiments and would like nothing better than to have the bike go to someone who would appreciate it for what it is. But alas, that was not to be. It had been for sale on a few sites and platforms and nothing came of that so I have to do what I have to do. And it is well on the way and I have already let go of any attachment I have to the bike being original. I figure there is quite a few of the original R90S's out there.

Stay well and keep riding, sir.

Sri