1975 BMW R90S
Presentation
This 1975 BMW R90S is finished in TT Silver Smoke and is powered by an 898cc opposed-twin linked to a five-speed transmission and an enclosed driveshaft. Equipment includes an electric starter, dual Dell’Orto carburetors, a chrome dual exhaust system, dual front disc brakes, wire-spoke wheels, a quarter fairing, a clear windscreen, a friction-style steering damper, a two-up seat, and a rear grab handle. The seller purchased the bike on BaT in May 2026 and subsequent work included rebuilding and synchronizing the carburetors, resealing the gearbox, and resealing and aligning the fork in addition to other maintenance items. This R90S shows 34k miles and is offered with an owner’s manual, a tool kit, recent service records, and a clean Colorado title in the seller’s name.
The bodywork is finished in TT Silver Smoke with gold pinstriping. Details include a quarter fairing with an integrated windscreen in addition to a refurbished two-up seat, a rear grab handle, folding passenger foot pegs, and both center and side stands.
The 19″ and 18″ wire-spoke wheels with alloy rims were mounted with 3.25″ front and 120/90 rear Bridgestone Battlax tires in September 2025. Suspension consists of a leading-axle telescopic fork as well as dual preload-adjustable shocks mounted to the swingarm on the left and the final drive enclosure on the right. Braking is provided by dual single-piston calipers over cross-drilled rotors up front, along with a drum at the rear. Work in 2026 has included resealing and aligning the fork, greasing the wheel bearings, balancing the tires, and replacing the brake pads.
The chrome-finished handlebar carries dual chrome mirrors and is mounted to the upper triple clamp ahead of a friction-style steering damper. MotoMeter instrumentation consists of a 140-mph speedometer and a tachometer with a 7,100-rpm redline, as well as a voltmeter and an analog clock. The five-digit odometer shows 34k miles. The instrument cluster was removed and cleaned in August 2026.
The air-cooled 898cc opposed-twin features dual Dell’Orto carburetors, a chrome dual exhaust system with a crossover pipe, and an electric starter. Factory-rated output was 66 horsepower and 55 lb-ft of torque. Work by Airhead Barn of Boulder, Colorado in June 2026 included performing a leak-down test, adjusting the valve clearances and ignition timing, changing the engine and transmission oils, rebuilding and synchronizing the carburetors, cleaning and adjusting the throttle body, repairing the choke assembly, and replacing the fuel hose.
Power is routed to the rear wheel through a five-speed transmission and an enclosed driveshaft. Work in August 2026 included cleaning the flywheel, engine block, and gearbox in addition to rebuilding the shift mechanism and replacing the seals, clutch, and rear main seal.
Bids & Comments
Alfalfanut (The Seller) 156
Nov 2, 2026 · 14:19
The reason I am selling this bike and probably the R100r you may notice in some of the photos is that I will be 71 years old in a few months. These are becoming too much bike for me. Getting old ain’t pretty.
Alfalfanut (The Seller)
Nov 2, 2026 · 14:17
The Motometer clock has not been removed. All is good in the world. The original clock is still in place. I bought a small clock on Amazon that has a little adhesive pad that holds it to the lens of the original clock. I didn’t have the original clock checked as I prefer not to have it draining the battery. Happy to take that temporary clock off if bidders would like to see the original clock. I just have a thing about easily knowing what time it is when I am out riding.
Nov 2, 2026 · 14:03
I love these R90Ss and own 5 of them. The R90S is still relevant rider today as long as you don't have aspirations for wheelies!
While I have not studied the photos, a couple of things jump out at me. First, rebuilt DellOrto carburetors should not require any throttle manipulation on a cold start...just gas on (only need one side fuel tap on), choke on, key on and touch the start button. The bike should instantly fast idle on its own even after sitting for months. Second, I would much prefer looking at a non-working MotoMeter clock in the fairing vs. the current customization here!
While I have not studied the photos, a couple of things jump out at me. First, rebuilt DellOrto carburetors should not require any throttle manipulation on a cold start...just gas on (only need one side fuel tap on), choke on, key on and touch the start button. The bike should instantly fast idle on its own even after sitting for months. Second, I would much prefer looking at a non-working MotoMeter clock in the fairing vs. the current customization here!
Nov 2, 2026 · 06:26
Begging the question- after all you did why are you selling this bike? What's wrong?
Oct 31, 2026 · 22:34
In the video what is the cause of the loose left side exhaust?
Iamsag
Bid
Oct 31, 2026 · 08:52
Bid in the amount of $2,600
hendersr64
Bid
Oct 28, 2026 · 10:30
Bid in the amount of $2,500
Alfalfanut (The Seller)
Oct 27, 2026 · 20:26
Repairs performed on the motorcycle by Airhead Barn in Boulder Colorado in 2026 include:
Engine oil and filter changed
Gear oil changed
Valves adjusted
Dellorto carburetors (including choke assembly) removed, rebuilt, replaced, and tuned
Brake master cylinder rebuilt
Brake calipers rebuilt
Stainless steel brake lines installed
Organic brake pads installed
Fork legs removed, cleaned, seals replaced
Forks aligned on two axis
Front and rear wheel bearings greased and preload set
Final drive removed greased re-installed
Crown gear splines replaced
Swingarm removed, bearing replaced, reinstalled
Gearbox removed, inspected, resealed, shimmed, installed
Shifting mechanism rebuilt
Clutch removed and completely replaced
Oil pump inspected; o-ring replaced
Rear main seal replaced
Instrument cluster removed, cleaned, reinstalled
A leak-down test showed right side has 3% leak through pistons; left side has 5% leak through pistons, Airhead Barn noted “anything below 10% is considered good”. Bike includes BMW panniers taken from another 1975 R90/s and include original keys.
Engine oil and filter changed
Gear oil changed
Valves adjusted
Dellorto carburetors (including choke assembly) removed, rebuilt, replaced, and tuned
Brake master cylinder rebuilt
Brake calipers rebuilt
Stainless steel brake lines installed
Organic brake pads installed
Fork legs removed, cleaned, seals replaced
Forks aligned on two axis
Front and rear wheel bearings greased and preload set
Final drive removed greased re-installed
Crown gear splines replaced
Swingarm removed, bearing replaced, reinstalled
Gearbox removed, inspected, resealed, shimmed, installed
Shifting mechanism rebuilt
Clutch removed and completely replaced
Oil pump inspected; o-ring replaced
Rear main seal replaced
Instrument cluster removed, cleaned, reinstalled
A leak-down test showed right side has 3% leak through pistons; left side has 5% leak through pistons, Airhead Barn noted “anything below 10% is considered good”. Bike includes BMW panniers taken from another 1975 R90/s and include original keys.
Jeffctsvman
Bid
Oct 27, 2026 · 18:56
Bid in the amount of $1,975
Alfalfanut (The Seller)
Oct 27, 2026 · 18:42
There were a few surprises for sure but once I saw Airhead Barn’s work, I said let’s hit everything.
Oct 27, 2026 · 09:15
Wow big bucks spent after the purchase in May 2026. Was it really preforming that badly when you got it or just a labor of Love?
faststock123
Bid
Oct 27, 2026 · 06:26
Bid in the amount of $950
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