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BMW R75/5
The Wayfarer's Choice
Text of Cycle World Road Test, July 1973
There isn't much question as to the intentions of BMW engineers when they
designed their shaft drive 750. Produce a motorcycle that is capable of
traveling great distances with a minimum of maintenance hassles. Allow for
maximum rider comfort. Build a reputation for manufacturing one of the world's
finest touring motorcycles.
The latest R75/5 is precisely that, with a touch of superbike thrown in.
Add the bonus feature of economy to the creditable performance figures and
you're faced with the prospect of riding a very desirable machine.
BeeEms don't often give way to major change, for they are a motorcycle
smelling strongly of tradition. And though tradition has its strong points, the
policy can often hold back progress. Fortunately for BMW, this is not the case.
BMW is apt to improve a machine during the model year, rather than wait until
new model introductions. For example, our test machine, a 1973 model, was the
last of the 55-in. short wheelbase versions. Later models (unofficially
1973½) got the swinging arm extended 1½ in., a change BMW says is so minor
most people will never notice.
The extra length is to allow the rider additional clearance between his shin
and the Bing carburetors, long a sore spot on the 750cc horizontally-opposed
twin. An alternate bonus of the increased wheelbase should be a smoother ride at
highway speeds, and BMW says that handling will not be affected. To identify
models with the longer swinging arm at your local dealer, look for black fuel
lines and flat black intake tubes to the carburetorsx. They were previously
silver.
Other than those few items, new BeeEms are quite similar in all respects to
last year's version. And as before, the 500cc and 600cc models are available,
though the 75/5 series outsells the R60/5 by nearly eight to one. Since the
difference in price between the smaller models and the larger and faster 75/5
isn't that much, most buyers are more than willing to fork over the extra cash
and ride home on the top of the line. They also find that when it is time to
sell, the 750 has the best resale value, though all BMWs rate high in this
respect.
And once a buyer has decided that, indeed, it is a BMW that he wants,
choosing the model is an easier proposition than with most brands. This is due
to the fact that all BMWs are identical with the exception of bore size,
carburetion, and the model nameplate on the sides of the engine.
There is no worry about which model has what, because if one has it they all
do. Simply decide how fast you want to motor, the health -and welfare of your
checkbook balance, and pick one of seven colors.
Purists stood back and examined the new styling treatment of the 1972 models
when they were first introduced. Most were unhappy. The chromed fuel tank
panels had them aghast, not to mention a few other new styling touches. But
apparently the changes caught the eye of a new group of buyers, and Butler &
Smith, BMW's U.S. distributor, reports that the new design was more than
successful. Sales went up. The chrome stayed. The purists frowned. But they can
order the old style 6.2-gal. tank as an option if they'd rather.
To the average rider the BMW comes off looking strange indeed. After all,
his cylinders aren't sticking out the sides like that. But little
do the neophytes know about the advantages of such an arrangement. The opposed
twin has those jugs sitting out there in all that cooling air rushing by.
Overheat? Not on your life.
Too, routine servicing becomes a simple task, because plugs and carburetors
are out in the open with nothing to prevent easy access. Even valve lash
adjustment offers no problems. And BMW is thoughtful enough to include a tool
kit that contains everything you'd need for a roadside repair. Among the goodies
is a tire pump, extra patches, and even a rag.
Though a BMW may look like it's on the hefty side, don't let the thing trick
you. The R75/5 is one of the lightest 750s available, and considerably lighter
than the majority of big bore machines. This has been accomplished through the
extensive use of aluminum alloys and lightweight materials such as plastic.
Again, the traditionalists will probably get upset over the mere mention of
the word plastic, but it has its good points. For example, both fenders are
plastic, but you'd never know unless you gave them a tap. They are feather
light, they don't dent or rust, and they'll probably never crack from vibration.
A duplex cradle type frame is used which features lightweight oval tubing in
the main sections. The triangulation of bracing serving as the seat and rear
fender support is removable, unlike most frames. Welding is on par with past
BMWs, which is to say that it's quite good. The engine/transmission unit bolts
directly to the frame with no rubber mounts or cushioning whatsoever.
The 745cc flat twin is mechanically interesting to look at. In fact passersby
with no interest whatsoever in motorcycles are likely to pause and ponder a
moment.
Models from a few years back had lots of iron bits and pieces throughout, but
the modern day BMW has made the switch to alloys. Now we find aluminum cylinders
with a cast-in steel liner for better longevity. The main engine casting is
alloy, as well. Though the unit appears as though it is on the tall side, the
upper portion is comprised of an air chamber and housing for the electric
starter motor.
The heavy pieces such as the forged steel crankshaft, steel connecting rods,
and camshaft, are positioned down low. So in spite of the way it looks, the
center of gravity is where it should be. And to help with cornering clearance,
BMW raised the cylinders slightly a few years back, and that's where they've
been ever since. The change made it necessary to place the camshaft below the
crank, rather than above, but now the cam benefits from better lubrication.
Bend down and look at the bottomside of the engine cover, and there is a
large cast aluminum sump cover with cooling fins. This aids in dissipating heat
from the nearly five pints of oil contained in the oiling system, which is
circulated by a Eaton-type pump through a full-flow oil filter. Since plain-
type bearings are used in the engine, an efficient oiling system is imperative.
A double-row chain connects the crankshaft and cam together, and features a
tensioner unit to help eliminate any vibrations which may be present. Doing away
with chain slack also helps somewhat in making the engine mechanically quieter,
and quiet is another one of those BeeEm traditions.
This is one motorcycle that was silent before it became fashion, and now when
other manufacturers are working feverishly to meet new requirements, BMW finds
itself concentrating on other items. They have a right to look smug.
It's interesting to note here that the 750 BMW has always been a strong
performer, but has always been left out of the superbike classification. Now
suddenly, many of yesterday's super machines are finding themselves with far
more restrictive muffling and air intake tracts, due to the new laws. As a
result, their drag strip times are falling off drastically, and again, BMW looks
pretty smug. If anything, they're going faster.
An automotive-type single plate dry clutch is continued on the latest models.
Lever pull is light and release is positive. So positive, in fact, that power
shifts produce impressive wheelies from first to second at the dragstrip. And
once again, BeeEm has reduced the size of its flywheels, so the old BMW clunk
during shifts isn't as prevalent. With the lighter flywheels, engine RPMs slow
much more quickly and as a result, engine and transmission speeds synchronize
just that much faster. Transmission gears were beefed up last year and no
changes have been made since.
Naturally, the feature that makes the BMW stand out in the local crowd of
wayfarers is shaft drive. There is no chain to lubricate, adjust, or sling oil
on rider and machine. This makes for an ideal situation whether you are on a
long trip or a short one. The driveshaft nestles inside the right hand swinging
arm member, and connects to a hypoid gear at the rear wheel. The gear rides in
an oil bath and is sealed, so the rider can virtually forget about it.
Rocking the 750 off its centerstand and climbing on feels funny if you've
never perched yourself on a BMW. The cylinders feel as though they'll get in the
way and they give you an impression that the machine is huge. But that's only if
you're staring down at them. And since most riders don't stare down when they're
in motion (we hope), they forget about the fact that they're there.
Since there is no key switch on a BMW, the ignition is turned on with a
little plug-in handle that fits in a hole on the headlight nacelle. In the
down position the ignition is on, and turning the handle left or right
operates parking or running lights. This is one feature on the BMW that is
annoying, and it makes theft easy since anyone with one of those plugs can start
your motorcycle and ride away. A key switch is a much better way to go.
Some choke has to be fed to the Bing vaccuum-type carburetors if the engine
is cold, and depressing the thumb operated button has the powerful electric
starter motor churning several revolutions before the twin fires. Once warm,
however, the engine starts with much less reluctance.
At idle the engine is quiet; blip the throttle and it stays quiet. But there
is that peculiar torque reaction in the lateral plane when RPM builds. It's very
strange for someone used to a more conventional machine.
Step on the shifter pedal with your left foot and pull away; there is a shake
throughout the bike at low RPM, but that disappears as revs build. And it's not
the kind of shake that gets to the rider, except for the fact that images do not
focus in the rear view mirrors. Only four speeds with this one, and that's all
the BeeEm needs to do business.
Around town you can stay in first gear and not bother anyone because of
noise, but you can also lug down the 750 in a higher gear if you don't mind the
shakes. All controls are properly spaced, but the Magura levers require some
reaching with the fingers to grab hold of them firmly.
Front fork action is strange. Apply the front brake and there is 8 in. of
soft compression. Yet, on certain street surfaces, the forks don't seem to budge
an inch, and the corresponding ride is harsh. The forks take the big bumps in
stride, but ignore the little ones completely.
At the rear, shock action is close to perfect over any surface. They even
place a handle at the bottom of each unit so the rider may change the settings
without hunting for the proper tool.
On some lengthy trips, staffers began to appreciate what BMW smoothness
means. Long rides and fast travel magnifies the comfort. And related handling
and braking is up to the overall performance of the motorcycle. There are minor
flaws and annoyances that keep the R75/5 from perfection, but overall refinement
approaches excellence.
But don't just pass judgment on a 5-mile tour around the block. Motor along
for awhile. The bugs may go splat and the trucks may go whoosh, but the
R75/5 doesn't give a damn. The BMW R75/5 is one sweet ride to
anywhere.
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