Our project 1974 BMW R90/6 may be in pieces, but we’re quickly getting traction on our build.
You might look at this photo and see simply a bare frame. We look at the same photo and see the fruits of hours of work, some of it ours (somebody had to strip it down), and some of it Stuart Armstrong’s.
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Winter is finally settling in here in the Midwest, and not a moment too soon. Why are we so happy for cold weather and the snowfall it invariably brings? One look at the Motorcycle Classics/Dairyland Cycle Race to Rebuild 1974 BMW R90/6 tells the story; we need to get some work done!
And thankfully, we finally are. OK, so maybe it doesn’t look like much just yet. You might look at the photo above and see simply a bare frame. We look at the same photo and see the fruits of hours of work, some of it ours (somebody had to strip it down), and some of it Stuart Armstrong’s.
Stuart, the owner of Custom Coatings & Metal, is our go-to guy for media blasting and powder coating, and true to form he’s worked his magic on our BMW’s frame. The results speak for themselves, and like every job he’s done for us before, our frame came back looking better than new. So far, we’ve had Stuart strip and paint the main frame, the rear subframe and the swingarm — and there’s more heading his way as we ramp up our Race to Rebuild BMW project.
We’ve been slow to reveal our plans for the BMW, alluding only to a leaning for a café-style road bike. That leaning has become a full-on bent as we’ve gone looking for inspiration, talking with readers and with the suppliers who are helping us pull this project together. Our BMW will have an unquestionable café style, but we’re keeping the focus on roadability and rideability. It’s an emphasis you’ve told us you like, and one our suppliers are helping make happen.
Take the Airtech fairing we’ve chosen. The leading manufacturer of fiberglass fairings for vintage — and modern — bikes (check the fairing on a vintage AHRMA racer the next time you’re at the track; chances are good it’s an Airtech), Airtech offers a mind-numbing selection of fairing options. Looking at their offerings, the hardest part is deciding exactly what you want. In our case, we’re opting for Airtech’s Ducati 900SS Café Half fairing. It may not be the standard unit you’d think of on a BMW, but we like it for its classic shape, sized to give a bit more protection from the elements and perfect for hunkering down for a fast blast down the highway — which is exactly where we see our BMW when it’s done.
We’ll match our Airtech unit with a Round Back Café Tail for long wheelbase /5-/7s from Boxer Café. This is a sweet unit, and we like how its nose slots into the rear of the frame’s top tube and how the back of the seat bolts to the rear hoop for a secure installation. We’ll also be getting one of Boxer Café’s fiberglass starter covers, a piece we think will really set off our R90’s engine. You can’t use this piece running a stock air filter, but our plans call for ditching the stock carburetion and air filters for a set of round slide Mikuni VMs from Rocky Point Cycle with filters from K&N Filters. Rocky Point Cycle has made a name for itself assembling conversion carb kits for BMWs, Nortons and more, offering kits with pre-jetted carbs to make final tuning a breeze.
Then again, we may end up having to do a little more tuning once we get our custom exhaust hung, courtesy of Tom Epperson at EPCO Exhaust. EPCO makes mufflers for a wide variety of vintage iron, and Tom is the fellow responsible for building all of EPCO’s stainless steel headers. Working with Tom, we’ve come up with a really slick 2-into-1 exhaust system that goes under the engine but keeps the centerstand, a piece many riders are apparently happy to live without but one we think is mandatory on a road bike. Ever try changing a flat on a sidestand? ‘Nuff said.
We’re also starting to pull together a lot of the little stuff, like a new lithium iron battery from Shorai. Smaller than the stock unit, it’s also an astounding 14 pounds lighter! That’s light enough that we might opt for the très cool battery relocating kit Boxer Café is developing, which places the battery under the seat tail fairing. K&N has already shipped us our air filters and a new oil filter, and the folks at All Balls Racing have supplied us with steering head, wheel and swingarm bearing and seal kits.
There’s a lot going on that you don’t see yet, like the unplanned valve job our R90 is getting. We knew we had to replace the pushrod tube seals, but that job ended up uncovering some ills on the left cylinder, including bad valves and a bad intake valve guide. Oddly, the right side was in fine shape, needing little more than a quick dressing of the valves and thorough cleaning of the head.
Colin Busch at Bob’s BMW has been helping us pull that bit together, supplying all the parts we’ve needed to get the engine back in shape. A dyed-in-the-wool BMW enthusiast, Colin’s knowledge of BMWs has been a huge help as we’ve uncovered one little surprise after another. Those have included the aforementioned cylinder head woes and the discovery that the clutch on our supposed original, 39,000-mile R90 is wasted. Either our bike had a ham-fisted owner or — more likely — it’s racked up a few more miles than the odometer indicates. Then again, that odometer was kind of hinky ...
More exciting is the dual-disc R90S front end that Colin found for us, a bit of kit that’ll really round out this project. Bob’s BMW also does a healthy business in used BMW parts, and as it turned out they had a set of R90S fork legs complete with calipers. Fitting those to our R90 is a fairly straightforward process, as they slip right on the standard R90 fork tubes and the required second brake rotor bolts onto the standard R90 hub. Sweet. Of course, we’ll be rebuilding the forks first, including fitting a set of Race Tech’s Gold Valve Cartridge Emulators and Race Tech fork springs, pieces that, we can tell you from experience, will utterly transform our BMW’s front end performance. Balancing out the back end of our R90, we’ll install a lovely set of Gazi shocks sourced from Flatland Custom Cycles — after we’ve installed new swingarm bearings, of course.
So that brings us back to today, so to speak, and where we’re heading with the Motorcycle Classics/Dairyland Cycle Race to Rebuild. We’re pretty excited about our project, and when we’re done, we’re going to have one slick café for the road. Although we haven’t finalized it yet, we’re leaning towards a dark color scheme, maybe jet black with a bit of smoked silver in homage to BMW’s iconic mid-1970s R90S. That’d go well with our black anodized Sun rims from Buchanan’s Spoke & Rim, which would look killer on satin-black powder-coated hubs bolted to satin-black powder-coated fork legs at the front. Stay tuned, because this is one classic BMW that’s really going to stand out. MC
Airtech: Fiberglass replica Ducati fairing and fairing mount
All Balls Racing: Steering, wheel and swingarm bearing kits
Bob’s BMW: Factory BMW replacement parts, R90S dual-disc fork legs and brake calipers
Boxer Café: Fiberglass starter cover, café tail section and seat pan
Buchanan’s Spoke & Rim: Custom wheel build with black anodized Sun aluminum rims and stainless steel spokes
Custom Coatings & Metal: Media stripping and custom powder coating
EBC: Brake pads
EPCO Exhaust: Custom 2-into-1 stainless steel complete exhaust system
Flatland Custom Cycles: Gazi Sport X shock absorbers
Joker Machine: Bar-end mirrors and turn signals
K&N Filters: Air and oil filters
Kenda Tires: Front and rear tires
Moto-Services.net: Hydraulic brake caliper overhaul
Race Tech: Front fork springs and Gold Valve Cartridge Emulators
Rocky Point Cycle: Dual 32mm Mikuni carburetor kit
Shorai: Lithium iron battery
Spiegler Performance Parts: Braided stainless steel brake lines, headlamp brackets
TC Concepts: Custom painting
Read the first Race to Rebuild article about this bike in Race to Rebuild: The BMW R90/6.
Read the second Race to Rebuild article about this bike in Race to Rebuild: The BMW R90/6 Part 2.