Race to Rebuild: The BMW R90/6 Part 4

By Motorcycle Classics Staff
Published on February 8, 2013
1 / 9
Like every build we’ve done, our 1974 BMW R90/6 has seen more then a few twists and turns in the road to completion.
Like every build we’ve done, our 1974 BMW R90/6 has seen more then a few twists and turns in the road to completion.
2 / 9
We’ve ditched the stock clocks in favor of a Motogadget Motoscope Pro. It’s minimalist and very cool.
We’ve ditched the stock clocks in favor of a Motogadget Motoscope Pro. It’s minimalist and very cool.
3 / 9
New 32mm Mikunis replace the original Bing units.
New 32mm Mikunis replace the original Bing units.
4 / 9
A new diode/rectifier board replaces the original unit, which was failing.
A new diode/rectifier board replaces the original unit, which was failing.
5 / 9
Relaced wheels from Buchanan’s are fabulous.
Relaced wheels from Buchanan’s are fabulous.
6 / 9
The BMW’s castings are decidedly porous, a fact brought to light during cleaning, which was a real challenge.
The BMW’s castings are decidedly porous, a fact brought to light during cleaning, which was a real challenge.
7 / 9
Gazi Sport X shocks look perfect, a huge improvement over stock units.
Gazi Sport X shocks look perfect, a huge improvement over stock units.
8 / 9
The engine cover will be black like our new valve covers.
The engine cover will be black like our new valve covers.
9 / 9
Lovely seat from Tom’s.
Lovely seat from Tom’s.

If you’re disappointed not seeing the finished Motorcycle Classics/Dairyland Cycle Race to Rebuild BMW, don’t be. We could show you more, but then we wouldn’t be able to tell you more about our race to the finish, and we wouldn’t be able to show you the finished bike with, we hope, its new owner.

OK, so maybe we like stringing things out a bit. But in this case we have a good reason, namely the simple fact that as of press time, the winner of the Motorcycle Classics/Dairyland Cycle Race to Rebuild Sweepstakes hadn’t been confirmed. Because of that, we decided it’d be more fun to wait until next issue to unveil our finished BMW and let everyone, the winner and the rest of you, experience the finale at the same time.

Like every build we’ve done, our 1974 BMW R90/6 has seen more then a few twists and turns in the road to completion. Last issue, we told you about some of the unexpected mechanical issues we had to sort through (cylinder head woes, instrument woes, etc.). Since then, we had a few more head-scratchers, most notably figuring out how to mount the très cool replica Ducati 900SS fairing we got from Airtech.

Following an established practice of “ready, fire, aim,” we settled on the fairing we wanted before researching how to attach it. When we discovered there are no kits to mount Ducati fairings on BMWs, we just dove in deeper. If you’re a commercial fabricator, mounting a fairing is just another challenge in metal, cutting and welding your way. But we’re not commercial fabricators, and while we keep swearing we’re going to learn to weld, neither of us has. So we did what we always do, and that was spend a little extra time — time we didn’t really have — figuring out a way to mount our Ducati fairing. Eventually we did figure it out, and next issue we’ll show you what we came up with.

Another issue was instrumentation. Originally, we liked the idea of keeping the stock clocks on our Beemer, but eventually we decided the cost of overhaul just didn’t make sense. Used units are expensive — if they work — and a speedo/tach rebuild can run from $350 to as much as $1,000. Enter Spiegler Performance Parts, who sell an amazing array of digital instruments including the super hip Motogadget Motoscope Pro. For about the same money as a rebuild ($547 with the mounting plate) we got a new digital speedo/tach that’s easy to configure, plus it is set up to accept optional “breakout” boxes to let you input just about anything you could possibly want to through the Motoscope Pro. And by way of major bonus, it looks fantastic on our custom R90.

We also had Spiegler perform their BMW brake rotor conversion. We didn’t strictly need a new rotor, but we were intrigued by Spiegler’s conversion, which involves removing the stock rotor from its carrier and mounting a new stainless steel rotor on buttons for a semi-floating disc brake. It should work excellently and it’s also cost-effective, as a stock replacement rotor from BMW runs $350 and the Spiegler conversion is $240. Very cool.

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