Upon my return to my little garage in Jefferson, the more I looked, the less I liked.
Ham Pugnus’ footprints were everywhere. With the tank pulled and the old engine removed, there was devastation as far as the eye could see. The bike’s wiring harness had been butchered – the process of mounting the departed Windjammer fairing had been performed in the most destructive manner imaginable. Rather than finding the correct leads where they terminated in the headlight bucket, our artist had split the harness under the tank where the bundle is protected by several layers of fabric tape, and then used electrical clamp style splice connectors – which partially split the original conductor to make the connection.
If there is one connector type one does not want to use for motorcycle applications, these are they. Their sins are manifold – they damage the original wire conductors, they breach the insulation, they corrode easily, and they have a tendency to fail when exposed to vibration. Zero for four.
I’ve seen what happens, close up, when a motorcycle wiring harness fails catastrophically, whether through heat damaged insulation, vibration or other abuse – like this. If your idea of fun is putting out the fire that was formerly known as your motorcycle, be my guest.
If this job was going to be done right, the whole wiring harness was going to have to go.
Indiana Jones has an unnatural fear of snakes. At this time in my young life, vehicle wiring was my snake.
Stripping this motorcycle down by removing every single connection was going to be a gut check moment for me. I was just going to have to ignore my whole cave full of snakes and somehow manage to be organized and calm – Rattler! – and get the whole thing back together correctly, or risk having my cheaply obtained prize turn into a pile of loosely related smoke leaking non-functional garage sculpture.
The wiring was not the only problem.
The /6 vintage motorcycles —of which the R90S is one — included the first disk brake system that had ever been used by BMW. For some reason, the BMW engineers were so scared of the whole notion, that they located the master cylinder underneath the fuel tank, where it was operated by a cable running from the hand lever. The system was short on feel, short on power, and encouraged folks to ignore the condition and maintenance of something they couldn’t see. By the time the bike was 15 years old, this notion was revealed to be as silly as it currently seems. Today, every single motorcycle has its master cylinder right up on the handlebars. The world has not ended. The stars are still in the skies.
My master cylinder, having suffered the fate of being ignored, and of having sat in a barn for several years, was not doing well. It appeared to be seeping from somewhere – whether through inaccurate filling or blown hydraulics – and the brake fluid was stripping the paint off the frame backbone and doing more damage to the relays and coils that sat underneath. The rubber brake lines attached to it didn’t look too happy, either. And while somebody that wanted to restore this bike for profit would have run right out and bought another one of these abominations, I just wanted my bike to stop with authority. I was pretty confident that an upgrade to more modern brake hydraulics, and maybe some stainless steel lines was not that difficult, and added that to my growing list.
I’ve had more than my fair share of conversations with mechanics.
One of the scariest things that ever springs from their lips is the phrase, “You know, while we’re in there….”.
‘While we’re in there’ can result in replacing a transmission just because it’s currently out of the car. It can result in the complete overhaul of a motor that went into the shop for a leaky valve cover gasket. I’ve seen ‘inthereitis’ end up replacing water pumps, timing chains, idlers, belts and hoses when investigating a squeak from the engine compartment.
This job was shaping up to be the mother of all ‘while-we’re-in-theres’.
By the time a detailed triage was done, I’d added a complete exhaust system and a clutch to the list of things that would be far easier to service while everything was apart.
I’d be dammed if I was going to have to pull the complete exhaust system again just to do an oil change. Of course, no job would be fun unless Ham Primus had destroyed something really critical to its completion. In this case, our man had stripped out 3 of the 4 nuts that hold the stock mufflers to the frame.
Did I mention that those nuts are welded to the frame?
Didn’t think so.
It is amazing what a tap and die set can do, but I’m getting ahead of myself.
I located a set of brand new Bub mufflers, and some reproduction headpipes from an English supplier.
The complete clutch pack was all BMW – I assumed that with the entire power train out and the bike completely stripped that if I made sure that the entire driveline had been renewed, it would be a goodly long time ™ before I’d have to spin wrenches in anger and go in there again.
I have occasionally been guilty of extreme hubris.
All things considered, the R90S went back together far more smoothly than I had any right to expect.
I remember spending a good deal of time, in that era before digital cameras and ubiquitous camera phones, walking around the bike with a yellow legal pad and a Number 2 Ticonderoga, writing down every single electrical connection on the bike by connector number, wire color and position. Where routing looked chewy, I drew pictures. All in all, my Snake Anxiety – bordering on full blown Serpent Paranoia – served me well. I was so overprepared that a kindergartner could have rewired that bike with those directions. Those 5 or so sheets of legal pad are still folded up in my shop manual and I still refer to them from time to time.
A friend of mine that did a small side business in used BMW parts and/or parts of questionable parentage turned out to have complete factory wiring harness for the S in his inventory. A modest sum – about a quarter of what BMW wanted – changed hands and the hardest part of what I was looking to do was sitting on my workbench.
The master cylinder upgrade was a known issue with these bikes – so much so that certain enthusiast dealers had kits that contained all of the parts required to make the swap look factory. The kit which I obtained had a Magura handlebar mounted master cylinder from a newer R80, a junction block which accommodated the original brake light switch and mounted on the frame backbone where the old master cylinder had been, and a set of brake lines – one rubber to run from the handlebar to the junction and two stainless steel lines to run from the junction to the calipers. It was an elegant solution that didn’t require any rewiring or re-engineering. Everything plugged right in and just worked.
I shared my plans for this bike with another bike business friend of mine, and he gave me that ‘Stop’ gesture and disappeared into the back of his shop. He reemerged several minutes later with a dusty piece of metal in his hands.
“Been looking for a good home for this. This is a San Jose BMW fork brace – this tubular steel structure is a direct bolt up that replaces that stamped bit that currently holds your fender. Much stronger – bike will corner and brake much better.”
Another small number of dollars changed hands.
He was right of course. It did and still does.
Replacing the harness turned out to be nearly trivial. I ended up placing the new harness alongside the old one and only removed one conductor at a time, replacing each one with its new equivalent. After about two hours, I re-wirewrapped the main harness into place on the frame backbone, and had a much deserved beer.
My blood pressure had remained nominal. There was no sweating, shaking or cursing.
The snakes, it seemed, had all be entirely slain.
It was a watershed moment for me. I had approached something of which I was irrationally afraid, and breezed right through it.
Breezed, anyway, if all this stuff worked when the rest of it went together.
These days, I’ll rewire anything.
You stand still long enough and I’ll rewire you too.
The motor went into the frame fairly easily, when you consider I was working solo. I remember having a few salty words getting the rear motor mount to line up, but a jack and some patience sufficed. I torqued the motormount bolts to spec and continued on.
The engine harness was connected to the chassis electrics and the starter cover from the old motor, with its R90S badges, was installed.
There were several special tools required to get the new clutch pack in place. One tool was a set of over length clutch bolts and matching nuts that were used to remove the old pack and the wrench the new one into place against the tension of the diaphragm spring. Those bolts came from a supplier called Maryland Metrics — MM is still around and has saved my Beemer-wrenching rear end countless times between then and now. The overlength bolts were screwed into the flywheel, and then the bolts were run down their length to compress the clutch pack. Then the stock length bolts could be inserted and torqued to spec.
The other tool was a centering arbor – designed and built by a gent named Ed Korn – that ensured that the clutch pack was assembled with all of its components properly aligned and ready to rock.
The whole transplant – with the right tools – was done with an efficiency that would have been impressive trackside.
The brake kit was extremely straightforward, and introduced me to the joys of bleeding hydraulic systems – remember, the Slash 5 was stopped by two drum brakes, actuated by cables and rods.
The transmission, swingarm bearings, driveshaft and brakes went together smoothly, and after some tap work on the frame’s mounting bolts, the new exhaust slipped in place. After a little delicacy getting it aligned, the fork brace was wrapped up. By this time, it was fairly late, so testing would need to wait for tomorrow.
When I got back to the garage, I rolled the bike into the driveway, set it up on the main stand, turned the fuel taps, and then inserted and turned the key. The telltales on the dashboard – at least the ones that worked before — were all properly lit. There was no flickering, no hissing sounds and no smell of insulation smoke.
This was looking good.
I made sure the bike was in neutral, set the chokes on the DelOrtos, pulled in the clutch, petitioned the lord with prayer, and pressed the starter button.
On about the forth compression stroke, the big motor fired, gave a snort and quit.
I pressed the starter again, and the motor caught and went into the signature DelOrto lumpy idle.
I rolled the throttle gently a few times, and it took throttle and revved.
It looked like we had a motorcycle.
In fact, we did have a motorcycle, which I rode almost every day for the next 10 years or so.
It wasn’t exactly pretty, and there were still some details that would have driven a purist crazy, and some things that drove me crazy. Unlike a lot of BMW twins, this bike was NOT refined. Where the /5 was glass smooth at certain RPMs, this bike was making power, and it told you about it in no uncertain terms. You could feel each power pulse, and the frame rang like a bell, at most legal speeds. For things to really smooth out and straighten up in top gear, you needed to be pulling over 5000 RPM and hanging out in a zip code that began somewhere around 90 mph.
If the /5 was easy, Proud Mary, the S bike was rough.
But rough as it may have been, it was a solid motorcycle, stable and trustworthy.
During those miles, I learned a few things. Given the miles I was putting on, I did some dumb things involving tires. I fitted reinforced touring tires – Dunlop 491s. I fitted tires that were larger than the OEM sizes – 4.00-18 rear and 3.25-19 front. Both dumb things made the handling of the bike into a truckish wrestling match, and were quickly discarded. Light bias tire in the correct sizes – Michelin Macadams proved to be the best – transformed the 90S into a virtual bicycle on back roads – the bike moved to the correct lean angles without thought and held them solidly. The Macadams are the most tractable tires I’ve ever had on a motorcycle – they communicated so clearly and linearly when they were going to begin sliding, and the rate of slide increase was always very linear. Spinning the rear wheel under control was simple. I even discovered – more or less by accident – that with the now braced fork and the Macadams, that one could gently drift the front tire to scrub speed on corner entrances, a very modern racebike trick that I assumed was well outside the capabilities of my Antique sporter.
I assumed wrong.
I even used the bike to commute back and forth from Maryland to Boston, when my consulting job was finding work there and not here. I remember running I-78 in eastern Pennsylvania on one of these runs, and hitting a thunderstorm so intense that the tractor-trailer drivers were pulling off and stopping by the side of the road. I remember being out on this huge grade, pulling up the mountain, with everyone else stopped, and the constant strobe light explosions of the lightning, and the wake the bike was putting off in the standing water on the roadbed.
That bike felt solid, planted, and like it would never miss a beat and would run like this forever.
But then I turned to the Dark Side.
To continue reading, Part Seven of the story can be found here…