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BMW R 69US

     

 

Make Model

BMW R 69US

Year

1967

Engine

Air cooled, four stroke, two cylinder horizontally opposed Boxer, pushrod operated 2 valves per cylinder.

Capacity

595
Bore x Stroke 72 x 73 mm
Compression Ratio 9.5:1

Induction

2x Bing Bing 1/26/9 - 1/26/10 carbs

Ignition  /  Starting

Magneto ignition  /  eclectic

Max Power

42 hp @ 7000 rpm

Max Torque

Transmission  /  Drive

4 Speed  /  shaft
Gear Ratio

1st 4.17 / 2nd 2.73 / 3rd 1.94 / 4th 1.54

Frame

Double loop steel tubular frame

Front Suspension

Telescopic fork

Rear Suspension

Long swing arm with suspension units and oil pressure shock absorbers

Front Brakes

Single 200mm drum

Rear Brakes

Single 200mm drum

Front Tyre

3.5 S18

Rear Tyre

4.00 S18

Wet-Weight

 200 kg

Fuel Capacity 

17 Litres

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 swing-

ing-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 l>e lucky to come up with five full inches of fork travel. BMW's has no less than 8v§ 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

Source road test 1969

 

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