R90S weight reduction

[sriman]

I'm hoping to reduce some weight off my 1976 R90S and to that end I'm looking for replacements for the stock seat, tank, mufflers and anything else that will make the bike lighter. Any help or advice is much appreciated.

Thank you,
Sri Nair
Manitoba, Canada.

[srankin]

Why? All the stuff you are talking about are part of the R90S. If you want to build a cafe racer bike, how about finding something else and save a real R90S for someone who wants one as it is? St.

[sriman]

Well, I tried to sell it but had no offers. I was asking $7,500 and was open to offers but nothing, nada. Bring a Trailer would not allow me to sell it with a reserve price, not even $6,000 and I wasn't going for that. I know my bike is not anywhere near concourse but it runs ok and looks decent. I just can't manage the weight anymore and would love for it to go to someone who will love it and use it well. This was not a decision taken lightly.

I'd truly appreciate any help and I'll just leave it at that.

[srankin]

Thank you for the explanation and I am sorry I may have been a jerk. I get a little touchy with some people who "customize bikes". Yours is a reason I haven't really run into so again, I am sorry to be negative.

I really don't know what to write about your not being able to sell it. R90S bikes have had a big following in the past and can go for sometimes crazy sale prices. I don't know why yours didn't.

So as far as lighter seats go, Corbin builds their seats with a plastic base instead of the stock steel base. From my experience, the weight saving is so small as to be almost negligible. Plus, Corbin's customer service I have found regarding airhead seats to be the worst in the business.

There is no one I know of that makes a plastic light weight gas tank for airheads. There are lighter starter motors I hear good things about but again, will you really notice the difference? A lot of folks seem to be installing the new high tech lithium batteries as they are smaller and lighter. There isn't much available for changing wheels.

Check out the website for Flat Racer, they sell a lot of cafe bike stuff.

It is too bad you are so far away to make it non cost effective for me to buy your bike or even offer to. BMW is a small bit of the motorcycle community, so riders and owners can be few and far between. Near me, guys are aging out and trying to sell bikes. Still bikes sit on the for sale ads for a long time before being sold or get marked way down in price. Good luck St.

[schrader7032]

I agree with ST to try and keep the R90S as is...iconic bike. Tongue in cheek, one way to reduce weight is to push back from the buffet bar!! At a minimum, I'd suggest doing things that are reversible. That way if/when you find someone who does want the bike, they can return it to original condition.

Something to think about is going to a lithium battery...I have not idea what kind to get, but they do save weight over the stock big-block battery. Not sure how much could be save in mufflers...some go to 2-into-1 but that means buying new headers. Plus, you'll need to futz with carb settings...you'll have to do that anyway if you get other-than-stock mufflers.

I just can't really think of much that can be changed to make a significant change in weight. If you remove something, like a seat, you'll need to replace it with something.

[sriman]

No worries, srankin. No offence taken.

I will only make changes that can easily be reversed when I'm finally done with the bike so that it will be back to almost original. I intend to replace the flywheel with a lightened one; replace charging system and battery to a lithium system and see what else that might be possible.

I appreciate your responses.

[srankin]

A lightened fly wheel my not give you much in overall weight reduction but it does help a bit with shifting. LOL, I think the performance gain in acceleration is pretty small. That is my feeling based on comparing bikes with the stock FW versus ones sent out to be lightened.
Shifting improvement however is better to a small amount. Unfortunately the biggest improvement in shifting came with not only the lighter FW in the newer bikes but the changes to the shift mech in the gear box on the newer bikes. My 78 RS shifted like a truck unless it was finessed. My 84 RT is much smoother and better.

So as far as changing the charging system, I don't see a real weight savings? To be honest, unless you really want to switch to a lithium battery and are using a lot of electrical gear or high wattage lights, the stock system will be fine.

I am completely useless on the subject of lithium batteries except to say read Snowbum' write ups and do a lot of research in various other airhead forums. My limited understanding is they require different charging voltages or some such thing as traditional batteries. So I am not sure if the stock or some of the aftermarket charging systems will work with them.

Good luck. St.

[sriman]

Thanks, ST. I know the flywheel lightening won't make a huge difference (maybe 3 lbs) but I think the lithium battery and the charging system to go with it would reduce the weight between 10-15 lbs. And I'll try to eke out a pound or two here and there and maybe try to add a pound or two of muscle to my spindly 120 lb frame!

Sri

[srankin]

Sri, it is always better to exercise and keep moving for riding, I am a good example lately of not and I am paying for it.

I had an accident on my RS last year, and am paying the price in a lot of pain. My lax lifestyle isn't helping the healing.

Anyway, I understand the pain in the butt of not being able to ride like I used to.

Research the Lithium battery charging systems. Personally, I am against a few of the aftermarket charging systems because they are so differently wired and installed than the factory system. If you go the route of a non factory style charging system, be sure to keep all the installation instructions and wiring diagrams in your tool box in case something goes wrong.

Cheers,St.

[sriman]

All the best with your recovery and continued riding!