Customizing a '76 R90/6

Hello, new member here. I have a '76 R90/6 that I am for the most part, happy with. I has about a bazillion miles (dead odometer/speedo). I also have a non running '77 R100S that is locked up, missing parts and in general, a parts bike.

Question is: I would like to put the front forks from the R100S on the R90/6 in order to run dual discs up front. I would also like to replace the rear drive unit to get a little more top end speed and to also be able to use the speedo/odo. There are other various and sundry items that I would like to switch over. However!!!! Would I be compromising whatever collector value that the R90/6 might have by doing this?

Welcome!

From this site it appears that the /6 and '77 tubes are the same type, so it should be a dead swap.

As far as collectibility of the /6, I don't think that model is really on that kind of level...the R90S more likely, but not the R90/6. It's your "stuff"...!!

+1 on the Welcome! I have a 76 R90/6 and the only customs on it are the Candied Red Metallic paint job and updates on front and rear shocks. Otherwise, I'm keeping the rest original. If I had a 77 R100S, I would resurrect that 'S' bike. Just my personal opinion!

Mike Horne
76 R90/6
93 R100R Legend

I agree on restoring the S bike but there is no title, other parts are missing and the engine is seized. The R90/6 has been coast to coast. IMHO it still looks wonderful but she is truly a rider. At best, it is a $3000 bike. I just don't want to turn it into a $2000 bike. Plus by putting parts on it from a "newer" airhead, it would not be like cobbling a set of 10" over CB750 forks on it.

The final drive that is on the /6 now is in decent shape with probably 50k miles left on it. The one on the S is an unknown quantity.

In my opinion, I don't think you would be compromising the value much because the parts you mention (forks with dual discs, rear drive, instrument cluster) don't change the stock look of the /6.

I think where you might change a $3000 bike into a $2000 bike is if you start making a lot of visible changes so that on looking at the bike, first impression is "frankenbeemer".

Barron

A standard /6 is a rider. Enjoy it for that, put as little money into it as necessary to make it work well for you (no motor hop-ups, etc), and don't look back on your decisions.

my opinion , to many is of little worth, ( my opinion)
yes disc brakes x2 are a beautiful thing
but customize ?
I hate that word for old BMW's to a point, always makes me think of people maknig them into "cafe" racers, or th eperson who recently was on fleabay and put tons of chrome on the bike adn called it "custom"
to me that is a sin for an old bike, unless it is a worthless basket case and a person on limited budget, to customize it
not saying that is what you are intending,
yes good brakes, reliable and easy to service elcectrics , go for it.
but more custom for an old bmw, if that is your lookiing for, for a modern bike with sex appeal, , go find a jap crotch rocket and take it from there

then again , maybe a person is in their 20's. its thier first bike, and they are thinking, way cool, I cam ,alke this better


ok folks...........flame on me

The R90 is your buddy

Just keep all the parts so the future collector can restore everything back to its origianl condition, and likely reap little for the effort. If, on the other hand, we're talking a '37 540K Merc., there's some real cash in the balance. 2 sense, bikes in general are for riding, fixing up, seeing the country. It's just a really good bike, have fun. Some think the 900 was about the rightest size in the development of the 247 series.

Got my R90 for a song in '87. It had a '77 rear wheel and hub. Go figure? Still enjoying the bike, and still finding out stuff about it as time goes by.

I guess it would all depend on one's definition of "customizing". Some folks who shall be un-named consider that to be skulls and flames. I consider it to be modest chassis and performance upgrades.

Since I still have the carbs for the S, has anybody ever tried a swap. Are the carbs the same? About the only engine performance issue I have with the /6 is spark knock on days when the ambient temperature is above 90 degrees.

Just one more opinion

banzaibob said:

Hello, new member here. I have a '76 R90/6 that I am for the most part, happy with. I has about a bazillion miles (dead odometer/speedo). I also have a non running '77 R100S that is locked up, missing parts and in general, a parts bike.

Question is: I would like to put the front forks from the R100S on the R90/6 in order to run dual discs up front. I would also like to replace the rear drive unit to get a little more top end speed and to also be able to use the speedo/odo. There are other various and sundry items that I would like to switch over. However!!!! Would I be compromising whatever collector value that the R90/6 might have by doing this?

Click to expand...

I will offer another silly opinion - rebuild the 77 R100S and you will have something becoming more rare with each one which is "scraped".

You did say the /6 runs well - Leave it alone and rebuild the "S"!!

Seized engine? No problem - time and money for a classic!!

Hey, you asked for opinions

I'll second that -- rebuild one ride the other.
and while you are deciding, let's see some pics of this bazillion mile /6.

.

What I usually ride around on...

Wel, I guess I'm going tohave to weigh in on this too!

There are several ways to look at this but first some facts.

The R90/6 is one of the best bikes that BMW built, bar none. Why? because 90% of the issues with the earlier bikes were fixed and when BMW went to 900ccs, everything kind of fell together. The 900's have plenty of power, great MPG if tuned correctly, they breathe well, easy on parts, They'll ru 100+ all day, etc, etc, etc. The only thing missing is dual disc brakes.

Collectibility? IMHO, the /6 bikes are going to be the next Airheads to become solid collectibles and it's going to happen while almost everyone, is looking at something else. I'd give it five years max 'cause the bikes are dwindling in number and prices are rising as we speak. That should tell you something right there. Keep that /6 and do whatever you want with it but hold on to whatever you take off of it and don't compromise your ability to return it to stock. I owned an R90 and it was a great bike! Just terrific...!

Yes, the R100S front end is a direct swap onto your /6 and the job can e accomlished in an afternoon if youhave all of the oarts in house and ready to go.
Please note that there were two slightly different caliper systems for the ATE equipped bikes. The R90's used 38mm Calipers, while the R100 was equipped with 40mm parts. If I was you, I'd try to find the right hand leg and the caliper as a package deal. OTOH, if you end up swapping in the later 40mm parts, make sure that your calipers are both 40mm. Swapping to dual disks is a snap. You can usually buy the parts for $250 to $350. Watch IBMR, Ebay, ADV and the Flea market here. Just have your cash ready and jump first!

40mm Carbs onto your R90? Forget it. The 32mm Bings are fine unless you go for Mikuni's or Dellorto's, both of which will give you somewhat better performance with a reduction in MPG.

Those R100S's are nice bikes! They too are fast emerging as soon-to-be-collectible classics. IMHO, thats a bike worth hanging onto, even if restoring it becomes a long term project. Those 1977 R100s were imported in very limited numbers and the RS version has already taken off. Can the "S" be far behind? I doubt it. Once again, the 77 "S" is a great bike. Fast and with solid handling. The frame is stronger than the /6, they're more powerful (Especially the 1977!) the controls were updated, they're very pretty and you can still find period go-fast parts, if you look hard. CC Products in particular, marketed a host of neat items for those bikes and they pioneered punching them out to 1050cc. Don't let the idea of the engine being stuck cloud your vision. Airheads get fixed every day and if it's mostly there, a restoration could make good riding AND financial sense.

Lastly, If you don't care about any of that stuff, you could take both bikes mix the parts together and build your own "Special". Choose whichever body style floats your boat, mix and match, bolt the R100 front end and fairing to the running R90, add a few later model parts, whatever wheels you like and SHAAZAM! Your very very own Hot Rod BMW!

I did that and I'm pretty happy with the result.

PS banzaibob: Please fill out you profile.

Keep that /6 and do whatever you want with it but hold on to whatever you take off of it and don't compromise your ability to return it to stock.

Click to expand...

In 1968 I bought a 1947 Harley-Davidson Knucklehead from an old farmer in North Vernon, Indiana. I paid $230 for it, and another $217 to a Harley dealer to rebuild the engine. I was hell bent to build a chopper and sold off, or scrapped, most of the stuff that came with it; jiffy stand, solo saddle, foot boards, crash bars, pursuit lights, saddlebags, fat tanks, tank shifter, speedometer, etc. I didn't even know what most of the parts were. I just kept the stuff that looked like "chopper".

After riding (and constantly working on) that hard-tail beastie five years I was looking for all of that stuff so I could return the bike to stock configuration. I wasn't intending to "restore" the bike, I just finally came to the realization that I enjoyed touring and that H-D actually did know how to build a comfortable road bike (certainly more comfortable than that little Bates solo that I called a seat, and 1200cc only goes so far (no very) on a one gallon peanut tank).

But then fate intervened ... a buddy bought a shiny new 1973 R75/5 for his wife and they took off on it together on a circumnavigation of the United States. They were gone all summer, and when they got back they sold her Sportster, and replaced his Panhead with a silver/smoke R90S (it must have been one of the first in Indiana). I bought my R75/5 a few months later, and sold the Knucklehead to a guy named "Bear".

When I moved to California in 1978 I saw a 1947 HD Knucklehead in restored condition at a local motorcycle shop; it belonged to the shop owner. He said that he'd turned down $25K for it; I was incredulous. Unbeknownst to me in 1968, I had a complete 1947 Knucklehead.

Keep the parts you remove, you just never know when you might want them again.

Easy to Do the Dual Disk

Thats a very nice looking bike, I wouldn't want to frankenbeemer it.
However, the dual disk upgrade is a very desireable thing, the single
disk just doesn't always cut it. My R60 with the front drum will out brake
my R90 single disk any day. I'm currently working on the dual disk conversion
myself.
An easy option for you is to swap the complete front end from the S bike.
Just drop it at the steering stem and move the whole assembly to your R90.
( I would put in new steering head bearings )
You will also need to swap the master cylinder. A new set of stainless steel
brake lines if you don't already have them and you're set.

As for a collector bike, I would seriously consider fixing the S bike,
If you have a little patience, parts can be found for reasonable prices
on E-bay, Just do a little research and don't get in to a bidding war.

Good looking bikes, Bob really like that Monza Blue!