The BMW R80s evolved from the 750
and then just kept on evolving slowly, like most primitive forms of life.
The R80/7 appeared in September
1978 and was basically a bored-out R75. It
had a duplex endless timing chain, contact breakers and mechanical
advance/retard, wire wheels, fork gaiters, single front disc and a solid
shaft
The British police were much
taken with the bike, and, largely at their instigation, a second disc went
on the front The front suspension was beefed up by reducing the damping rod
holes from four to two. All engines were the S model with 9:1 compression
ratio, Kinematics gearchange went on
soon after, in a half-successful attempt to get a half-decent gearchange
action. Cast wheels followed and brake calipers changed from ATE to Brembo.
These changes crept up osmotically on the Beemer, but in late '79 came a
major overhaul.
The seat changed to the sportier
R90S style and the rear light became the current twin-bulb type. Changes
also took place in the engine.
The timing chain changed over to
a single-row item with split link, which is worth remembering as it takes
half the time to replace compared to the duplex one.
The ignition was modified to get
out of the way of water and oil, and was put in its own container and
remotely driven, much like a car's distributor.
Fork gaiters departed and the
shaft drive finally got a cam-type shock absorber.
Production finished in 1980,
The engine continued in the R80G/S Paris-Dakar model, until the R80 was
brought back in 1983, featuring some of the C/S mods.
Faults and Quirks
BMWs are low-tech and
low-stressed, so often prove to be ridiculously long-lived Later models will
probably prove the better buy, if only because of their specification.
Ignition may well prove troublesome on earlier models since the original
points were at the front of the crankcase and could get water in from the
front and oil from the rear.
Equally, the early duplex timing
chains could take ten hours to replace even by a skilled mechanic, so the
later models' single-link will prove easier to replace. Listen for
clattering chains, which normally go about 40,000 miles.
On older models check for scuffed
wiring loom and blocked breathers. Also look for worn rear wheel splines, as
replacements are expensive. Wives can sometimes drop in at 50,000 miles or
so on a very tired engine
Electrics can prove troublesome,
beyond just the points. The mechanical regulators on older models should be
viewed with a jaundiced eye. The Varta batteries, horribly expensive that
they are, could be easily ruined, so replace with a similar sized car
battery that has the full 30aH wack. Generators are also weak.