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-   -   Bringing 74 R90S back to life after sitting 30 years (http://www.advrider.com/forums/showthread.php?t=730033)

_cy_ 09-30-2011 10:41 PM

Bringing 74 R90S back to life after sitting 30 years
 
Bringing 74 R90S back to life after sitting since 1979 ... parked with only 7,300 miles on the clock.
purchased from the original owner's son. This bike was the 41st R90S made to USA spec's off the assembly line. one of the first R90S to hit American soil and quite possibly the lowest mileage un-molested R90S in USA.

Was torn between selling this bike, purchasing a modern bike with proceeds and keeping it.
At first I thought it would be a shame to put mega miles on this R90S. But came to conclusion, that's what it was made for.

After thinking about it for a day.... nah... more like an hour... keeping the R90S!
It's my goal to bring this bike back to 100% mechanical condition. reliable enough to tour.

This thread is to document the process, that is if anyone is interested...

30 years of dust
http://img.photobucket.com/albums/v1.../bmw20r90s.jpg

http://img.photobucket.com/albums/v1...bmw20r90s2.jpg

http://img.photobucket.com/albums/v1...s/DSC08300.jpg

http://img.photobucket.com/albums/v1...de20covers.jpg

opposedcyljunkie 10-01-2011 12:56 AM

Interested
 
Nice find and good decision to keep it!

_cy_ 10-01-2011 04:42 AM

tires were leaking so pulled down front tire, only to find natural rubber tubes inside are in perfect condition. valve stem was leaking.

need help in deciding which tire to put back. Bike came with a brand new Metzler 3.25 x 19 tire still wrapped. what shall I do? find a modern tire to install and put back the original Metzler or just install the new Metzler?

will need to fabricate a tire balancing tool with bearings. best tube I could find locally was a Japanese made IRC brand.

after replacing valve stem in rear tire, holding air fine.rear tire appears to be pliable, looks & feels like new. will leave it alone for now.

http://img.photobucket.com/albums/v1...DSC08339-1.jpg

DoktorT 10-01-2011 05:23 AM

What a great project. Getting to safe and reliable for use is a worthy goal. I see a two stage process. First stage is partial dissassebly for cleaning and inspection.

Safety means new tires and tubes.

A through cleaning of tank, petcocks and carbs is required for reliability. Do that once right and be done with that. Do pull the front cover. Go over all the wiring terminals under there as well as the headlight pod and under tank area. Clean and tight everywhere.

Just standard maintenance elsewhere. Valves, oil and filter, lube, splines, head bearing and swingarm tension, the basics. New battery then just test all lights and switches.

Flush and renew the brake fluid, then pull the handle as hard as you can and verify firm and no leaks. Rebuild master and calipers if required.

Then you can fire it up and test drive, tune the carbs.

Stage two is to put a few hundred miles on it and see if you got some leaking seals somewhere and monitoring for proper function of all systems.

Sure hope it wasn't stored with gas in the tank and carbs.

Detroit Steve 10-01-2011 05:38 AM

DOKTOR T is right but left out one thing.


Clean and repack ALL bearings! the grease that was ok back in the day will be the consistency of candle wax today.


Enjoy that bike you lucky devil!!!!!

DoktorT 10-01-2011 07:37 AM

Quote:

Originally Posted by SlackerSteve (Post 16976765)
DOKTOR T is right but left out one thing.


Clean and repack ALL bearings! the grease that was ok back in the day will be the consistency of candle wax today.


Enjoy that bike you lucky devil!!!!!

Covered under basic maintenance I did mention. That includes everything listed under maintenance in the factory manual, including the wheel bearings and LOTS of other things I. No need for me to be redundant to exhaustion on this.

elite-less 10-01-2011 08:28 AM

Great base for a project! I'll be checking on this.

_cy_ 10-01-2011 08:30 AM

Quote:

Originally Posted by DoktorT (Post 16976712)
What a great project. Getting to safe and reliable for use is a worthy goal. I see a two stage process. First stage is partial dissassebly for cleaning and inspection.

Safety means new tires and tubes.

A through cleaning of tank, petcocks and carbs is required for reliability. Do that once right and be done with that. Do pull the front cover. Go over all the wiring terminals under there as well as the headlight pod and under tank area. Clean and tight everywhere.

Just standard maintenance elsewhere. Valves, oil and filter, lube, splines, head bearing and swingarm tension, the basics. New battery then just test all lights and switches.

Flush and renew the brake fluid, then pull the handle as hard as you can and verify firm and no leaks. Rebuild master and calipers if required.

Then you can fire it up and test drive, tune the carbs.

Stage two is to put a few hundred miles on it and see if you got some leaking seals somewhere and monitoring for proper function of all systems.

Sure hope it wasn't stored with gas in the tank and carbs.

thank YOU!

this is exactly what I need. don't know if fuel was drained. after sitting that long, it's completely dry.
who knows, I could get lucky and find everything completely clean and ready for fuel. will know after tearing into carbs. if fuel bowl is full of gunk, then everything is getting flushed.

didn't catch the part about repacking bearings as this is my first BMW and are not familiar with scheduled maintenance yet.

brake master cylinder needs to be replaced or rebuilt. I'd do that even if was working perfect. calipers are not leaking, so leaving them alone.

notice the entire engine is painted black, not just cylinder base. this was pointed out to me by several Adv members already. No question this was done at the factory as engine has never been out. all the factory tie straps are still intact.

don't know but speculate that when BMW factory was setting up assembly line for USA spec bikes. first few R90S got a few things done to it that rest of this model run didn't get. Serial # 4950041 matches on engine, frame and ID plate.

kraut.burner 10-01-2011 08:39 AM

subscribed :lurk

Renner 10-01-2011 09:13 AM

I'm in
 
subscribed :lurk

Where-abouts are you located?

We're having a tech day here next week... though odds are pretty slim that you're close enough to drop by for a visit.

http://renner60.smugmug.com/Other/Ai...86_7SqNv-L.jpg

_cy_ 10-01-2011 10:50 AM

located in Tulsa, OK ... hope to visiting a few Adv riders around the country in the near future on R90S.

sure wish I was closer to attend... does anyone know if slightly higher compression engine 9.5 to 1 still will run on regular? no problems getting premium in US. but I suspect down south, one runs what's available.

Renner 10-01-2011 11:22 AM

Quote:

Originally Posted by _cy_ (Post 16978142)
... does anyone know if slightly higher compression engine 9.5 to 1 still will run on regular?

You'll likely get good responses on this.
My take is no, not very well... better if you retard the timing.
You might give it a try and see if it pings (which it probably will, especially under load/hill climbs), but much pinging would be quite detrimental so go easy.

Pretty sure our current premium is lower than the factory recommended octane for your R90S but I don't have the operators manual on hand.
in other words, best to run the highest octane available.

ooweel 10-01-2011 11:29 AM

No Stalks?
 
You are not allowed to post 74 90s pics with out including pics of the mirror stalks. :lol3

east high 10-01-2011 11:46 AM

Quote:

Originally Posted by kraut.burner (Post 16977595)
subscribed :lurk

Me too! BTW, Isn't this the second 'hey check out my original r90s' thread in as many weeks? Lucky sods :D

jackd 10-01-2011 12:16 PM

Lucky you on finding this bike. As to your question on the need to use premium gas in your bike. A Triumph T100 that I restored had a compression ratio of 9:1 and I ran it on today's premium. If I really loaded it, it would still ping on occasion, so I made damned sure I never used regular gas. Seeing as your RS is 9.5:1, I would not even contemplate using regular gas. You have too nice of a bike to go for the less expensive grade of fuel. Put the additional cost of premium fuel as one of the expenses that come with owning a premium bike.


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