My first ride on a clean but high mileage BMW R90S left me less than elated. Thrown into the chaos of London traffic, the Teutonic monster complained by jerking all over the place as my boot fought a vicious game with the gear lever. Torque reaction from the shaft drive had the back end trying to go airborne and then flaying all over the road as I punched the box into a false neutral. The real neutral proved so elusive that I had to grapple with a dragging clutch at the traffic lights. When the motor stalled, the electric start sounded like it was falling apart, taking several minutes to persuade the engine back into life.
Also, having deserted bikes for a few years and not normally going near London, I had forgotten how crazy heavy traffic could be on a motorcycle. Most of the cagers appeared absolutely certain that I did not exist, forcing me to give the twin front discs a good work-out. It was whilst in such a wound up state that I let myself go, giving the beast a wild dose of throttle in second gear. The far distant gap in the traffic suddenly loomed near. No problem, thought I, until I suddenly recalled that there were two massive cylinders sticking out into the air.....
Calamity on my first ride. Tore a large swathe of metal off some poor dolt's Ford Fiasco with the left-hand cylinder. Nearly did the same to a Merc on my right but missed him by a few millimetres. As is often the case, I hadn't yet obtained insurance. I let the beast accelerate away, hoping no-one caught a glimpse of my numberplate. Reprehensible, perhaps, but anyone who rides a bike knows it's a dog eat dog kind of world out there.
Home was another 120 miles away. Didn't master the gearbox, could only change smoothly between third and fourth. The R90S has very tall gearing that needs lots of clutch slipping in town even in first gear. Needs about 2500 revs up before the engine begins to feel right. With a dose of vibration beyond 6000rpm, the effective power band is not exactly generous. To be fair to the old hulk, there's a lot of torque available within the confines of that band, with some stunning 60 to 90mph acceleration on hand.
Once out in the country, with the bike dumped in fourth, I had an easier time. I wasn't going to push an unknown bike much beyond 80mph, which was enough to reveal that the rear shocks had no damping. Pogo-stick time. I was also surprised at the amount of muscle needed to throw the Beemer through the bends. Didn't get anywhere near scraping the cylinder heads.
Once home, I was overwhelmed with relief at my safe delivery. I left the bike in the garage for over a week before I forgave its idiosyncrasies. The clock read 96000 miles, the last owner doing more than three-quarters of that mileage. Reckoned it was on its third clutch and fourth timing chain, but was otherwise original. He probably thought the bike was about to turn expensive in a big way and was happy to off-load it on some poor sap for 600 notes.
But I've always been a lucky sod with old bikes. The Beemer did an almost unbelievable 31000 miles with just the routine maintenance (about an hour a month) and a few minor problems. I did change the shocks for something newer out of the breaker and also had to do a minor rewire when use of the indicators caused the bike to catch alight. Some of the insulation had rotted away.
Once I was sure that the bike was not going to fall apart under me, and I'd fitted the newer shocks, it was time to see what she would do. 95mph came up no problem, the back end waltzing around mildly. Crouched down into the handlebar fairing to crack the magic ton. Before the speedo could hit the mark, the sleazebag went into a vicious speed wobble. Frightened the shit out of me, almost threw me clean off as I shut the throttle dead and hit the brakes. By the time I'd finished wrestling with the monster, ended up on the grass verge with a cylinder embedded in the earth.
Looked the chassis over but nothing obviously wrong. Blamed the tyres which had only a millimetre of tread left before they became illegal. Not being entirely thick, decided to limit myself to 90mph until I'd fitted some new Metz's (even then I never quite found the nerve to crack the ton). The other big shock was that fuel went through the massive carbs at less than 30mpg. A little bit of smoke out of the exhaust on the overrun suggested that the pistons and bores might need attention soon and the way that the carbs went out of balance every 200 miles, or so, indicated that they were as worn as the bores.
Soon, it was time for the summer hols. A fast canter around the wastelands of Wales. The BMW would storm down the motorways and dualcarriageways at 80 to 90mph but was a bit lost on the seriously twisty single track lanes that cut through the Welsh mountains. On a couple of occasions the torque reaction turned the drive-line lash so vicious that I was almost thrown off the side of the mountain. A restricted 125 could've made the Beemer look pathetic on those kinds of roads. The all up weight of over 500lbs had as much an adverse effect on throwability as the conservative steering geometry.
Despite the fitment of a fork brace by the previous owner the forks felt their age with enough slack to encourage judder when using the refurbished brakes. The gaiters hid perfect chrome under a layer of grease. The headrace bearings, though, were well gone and replaced with a taper-roller set. Being not entirely simpatico to engineering needs I managed to overtighten these. The resulting wild speed wobbles at 70mph nearly had me browning my trousers. I cursed my stinginess in not using BMW bearings, but was relieved to find all it took was a slight slackening off to revive the handling, er, finesse.
By then the engine wouldn't push past 95mph, so no hope of seeing if the 100mph speed wobble had been eradicated. I doubted it, the weaves were still there. Vibes were also reaching a disturbing level. I'd always been aware of two whopping great pistons doing the business down below, but by 125,000 miles it had become so bad that I was grinding my teeth away after a mere 50 miles.
BMW enthusiasts reckons it takes about 10,000 miles to master the gearchange but my gearbox and clutch were wearing out faster than I could learn the art of changing gear without the dreadful lurches and crunching noises. Second had become so elusive that I usually ended up in third with the smell of a burnt clutch plate.
The vibes did not do much for the battery, admittedly a non-standard car unit, that lasted for only 5 to 7 months. I managed to get the car accessory shop to swap the first one that went, but thereafter they told me where to get off. The front light was some ultra-powerful Halogen replacement that had car drivers terrified but blew every three months or so. Its use tended to drain the battery after about a 100 miles of riding, so it was a very mixed blessing. I eventually fitted a stock unit which has yet to blow but has made dark country lanes a bit dodgy.
Towards the end of its life, starting became very difficult, which further added to the stress on the battery. Usually took five to ten minutes to fire up on moderately cold mornings. Even a hot engine wouldn't fire instantly. New plugs helped for about a 100 miles. It didn't take an ace mechanic to work out that the engine was due for some serious attention.
Its demise was thus gradual, refusing to fail in a big way on the road, one morning the R90S simply declined to start ever again. Bumping a BMW is not recommended - didn't work anyway even with half the neighbours pushing.
One thing that should be said for this engine layout is that it's dead easy to pull off the cylinders. Half an hour's butchering with my spanners revealed that the wear had reached the crankshaft, all its bearings shot. With some quite deep score marks in the bores where the rings had broken after seizing solid into their grooves, it was surprising that the bike had run for so well and long.
As the chassis is still in a reasonable state I'm in the process of finding a newish motor, hopefully an R80. It has to be cheaper than replacing every singe component inside the old R90's engine cases...
Mike Boroughs