Four stroke,
two cylinder horizontally opposed Boxer, pushrod operated 2 valves per cylinder.
Capacity
594 cc / 36.2 cu in
Bore x Stroke
72 x 73 mm
Compression Ratio
9.5:1
Cooling System
Air cooled
Induction
2 x
Bing 1/26/9 - 1/26/10 carburetors
Ignition
Magneto ignition
Starting
Electric
Clutch
Single plate, dry
Max Power
31.3 kW / 42 hp @ 7000 rpm
Transmission
4 Speed
Final
Drive
Shaft
Gear Ratio
1st 4.17 / 2nd 2.73 / 3rd 1.94 / 4th 1.54
Frame
Double loop steel tubular frame
Front Suspension
Telescopic front fork with hydraulic damping
Rear Suspension
Swingarm, plunger type shock
absorbers
Front Brakes
∅200mm Drum
Rear Brakes
∅200mm Drum
Front Tyre
3.50 - S18"
Rear Tyre
4.00 - S18"
Wet-Weight
200 kg / 440 lbs
Fuel Capacity
17 liters /
4.4 US gal
.
BMWs are very much different from the run-of-the-mill
motorcycle, because they're built like an automobile. In fact, forget that
they ride on two wheels, and they're more like a car than a bike.
Let's start with the engine. And that will tell you why
the BMW is so like a car. Have you ever seen a Volkswagen engine out of the
car? Try to visualize two of the cylinders missing, and all the cowling pulled
off. The capacity of that engine would just about match the 600-cc. capacity
of the BMW. This may not seem big by automotive standards, but at 7,000 r.p.m.
it cranks out a very healthy 42 horsepower, and you've got to use a good grade
of gasoline, as the compression ratio is 9.5:1.
The clutch is just like the one in a stick-shift automobile;
it has a double-faced friction disk that rides on the flywheel, and a pressure
plate. The gearbox is also similar. It forms an integral part of the engine
housing, and internally looks very much like your automobile gearbox, too.
Each gear ratio is derived from pairs of spur gears that remain continuously
meshed during shifting, making for a smooth shift in every gear.
The rear drive also looks like a byproduct of automotive
engineering. If you split your car's differential right down the center, you'd
have exactly what you find on the BMW. You'd see a complete ring-and-pinion
setup; even a shaft drive and universal joint going to the gearbox. As I said,
the bike is more automobile than motorcycle.
It even rides almost like a car. The rear suspension is of
the pivoted swinging-arm type. The pivot point attaches to the rear of the main
section of the frame, and oil-damped shocks and rebound springs control wheel
deflection. The front suspension is a modernized version of the old telescopic
fork that BMW pioneered for motorcycles back in 1935. There are very few
machines today that do not use this type of suspension. It's just two
oil-damped hydraulic cylinders with a rebound spring on each one. The damping
action is progressive, which means that the farther the suspension moves,
either up or down, the stronger the action of the suspension.
BMW has an ace in the hole, too. Take any bike around, and I'd
be willing to bet that you'd lucky to come up with five full inches of
fork travel. BMW's has no less than 8 inches! I didn't really
appreciate this suspension until I was riding through Louisiana in a driving
rain. My speed was about 60, and as I rounded a sharp bend, what should I see
but a large, wet mattress right in the middle of the road. I had my choice of
sliding almost $2,000 worth of shiny motorcycle or trying to jump the
mattress. I aimed for the middle of the mattress and punched it head on.
I've jumped competition bikes before, but this was really
something out of the ordinary. The trick to jumping a motorcycle is to slide
back on the seat for weight transfer, and then roll the throttle on, as you
hit the jump, to keep the front wheel up in the air. I'll bet I was three or
more feet in the air with a machine weighing in at 448 pounds. Since I'm not
writing this from a hospital bed, you can
gather that I came down all right. To be truthful, the only
thing that kept me out of the ditch was that fine front suspension. The frame
of the bike, incidentally, is of the duplex cradle variety, and looks robust
enough to support much more than its engine and a rider.
Taking on the weather. In Louisiana, it began to rain. By
the time I entered Texas, the rain had turned to sleet and driving snow. I was
even stopped once by the state police and told that tornado warnings were out
and I would be proceeding at my own risk.
U. S. 80 outside Fort Worth and Dallas had flooded, and I took
the fully loaded BMW up into the muddy hills to avoid the backed-up traffic
and roadblocks. In one spot, just hours before, an overflowing creek had
washed a car off the road and the driver had lost her life. Again at my own
risk, I crossed this creek while bystanders cheered me on from both banks. A
BMW is just about waterproof, so other than a missing left cylinder (caused by
lack of a part someone had pulled off the plug cap), the bike putted across
like a submarine. (I found that as long as no water gets into the air cleaner,
the cylinders can be submerged without
missing a beat.) Even plowing through
snowdrifts, the machine performed faultlessly. —
What about gripes?
I do have a few. The speedometer was
one. It clouded up as soon as I hit rain, and still hadn't dried off for
visibility even when I was back in sunny California. When you're riding a
motorcycle, especially through small towns, you have to be very careful
of the speed limit. You sure can't do this if you can't see
the speedometer face.
Also, BMW has gone from a metal to a nylon float needle to
cure a minor problem of now-and-then flooding. Apparently the nylon needle has
not cured the problem completely—every once in a while I had to dismount and
whack the side of the float chamber with a rock to get my left carburetor
float to seat.
Believe it or not, these two were the only real problems I ran
into on a 3,200-mile trip.
Twice, in the mornings, when temperatures dropped way below
freezing, I encountered difficulty in starting, but these were the only times
during the trip that the bike didn't start on the first or second kick. And
once, when I parked for the night, I inadvertently left the fuel tap on, and
all the gasoline leaked out of the tank onto the ground.
Let's talk about the brakes. They were superb! The front
unit is a powerful double-leading-shoe type, and the rear one a single-leading
shoe. When I tested the brakes after I got to California, I found that it took
seven panic stops from 60 m.p.h. before there was any evidence of brake fade.
The brakes on a BMW are also the next-best thing to being completely
waterproof. The average mud puddle won't bother them at all, and they have to
be entirely submerged before moisture gets on the linings.
I'm happy to echo what Norbye and Dunne said to me after their
coast-to-coast record run with the Pontiac [PS. July]: "If I had to make the
same trip again, I'd pick the same machine." DjD