- Categorie: Rijtesten
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Text from "Motor Cycling" magazine, April 19, 1956
Introduced for 1956, the R26 BMW model is fitted with a highly tuned version of the earlier R25 engine and pivoted-fork front and rear springing similar to that previously confined to the 494cc R50 and the six-hundred R69. Outstanding characteristics of the two-fifty are its excellent riding comfort, superb steering, smooth, powerful braking, a remarkably high level of exhaust and mechanical quietness, goof fuel economy and a fine standard of engineering, detail design and finish. And, as the data in the information panel shows, the R26 possesses a high performance for a two-fifty.
On some modern machines a combination of a reasonably low seat and footrest setting with an ample range of wheel deflection results in a tendency for the footrests or other components to foul the road on corners. This is not so on the R26. The laden saddle height is low enough to permit a short rider to place his feet firmly on the ground when required and the footrests are sufficiently low to afford a comfortably wide knee angle; both front and rear springing systems allow ample wheel movement. Yet the model can be heeled over to an extreme degree when cornering without the footrests or other parts scraping the ground, for the width across the footrests is only twenty-one inches, while the silencer and centre stand are well tucked away.
Width of the tank between the rider's knees is also comparatively narrow (nine inches), while handlebar width is only twenty-five inches. The resultant riding position proved extremely comfortable at all speeds within the model's compass, and many consecutive hours were spent awheel without a trace of fatigue. Another feature contributing to riding comfort is a four-position saddle-spring adjustment which caters for riders' weights from 132 to 220 pounds.
Grouped in two clusters clamped to the ends of the handlebar, the hand controls were all very conveniently sited and sweet in operation. Though not adjustable for position, the rear-brake and gear pedals were also ideally sited.
In both front and rear shock absorbers, spring and damper characteristics are extremely well blended. Both wheel suspensions responded remarkably well to all varieties of road shocks from small ripples to pot holes, yet there was never any pitching. On full front-wheel deflection, caused by crossing a deep road hole at speed, the front number plate broke the headlamp glass. Mounting the plate an inch farther forward would preclude the possibility of its fouling the glass. (It should be remembered that the front number plates are not used in Germany.)
Steering of the race-bred variety made cornering a sheer joy, whether the bend was fast or slow, smooth or bumpy. Unusually little effort was required to heel the model over. Indeed, once the banking was initiated the R26 seemed to take matters into its own hands with superlative results. Of an equally high standard was the braking. Used independently, each brake could be made to evoke a protesting squeal from the tyre. Applied in unison, they would stop the model smoothly, safely and, if necessary, rapidly enough for any emergency. Although the brakes were intentionally not spared, no adjustment was needed during a test of just over 500 miles. Front brake torque is transmitted through the pivoted fork so that brake operation tends to raise the front of the machine, but not unduly so, and certainly not enough to cause fork judder.
Whether the engine was cold or hot, a first-kick start could virtually be guaranteed provided the carburettor was not over-flooded. If that was done the engine would fire readily if the kick-starter were operated with the throttle wide open. A throttle setting as for a fast tick-over was normally required for starting, in conjunction with momentary operation of the float tickler when the engine was cold or none at all when it was hot. Whatever the temperature of the engine, it would idle very slowly and reliably when the throttle was closed.
Incorporating bevel gears which actuate the throttle cable through the medium of a cam, the twistgrip has a differential action giving a slow rate of throttle opening in the lower ranges and a progressively faster rate as the grip is rotated further. This delicate control, in effect, enhanced the natural docility of the engine for traffic work and in conjunction with a low bottom-gear ratio, smooth transmission and high flywheel inertia, made it easy to ride the R26 a slow walking pace with the clutch fully engaged, and to accelerate sweetly from that speed.
With the exception that slight vibration was perceptible between 44 and 48 mph in top gear, and again at an indicated 60 mph, any speed between the minimum non-snatch figure and maximum was equally pleasant to use. On long main-road trips fifty miles were often packed into each hour by cruising on half-throttle or just over. This setting gave an indicated speed of approximately 70 mph under windless conditions on level roads; but speedometer flattery was about 10 percent throughout the BMWs speed range. When tested for stamina, the R26 was ridden for several miles on end on full throttle without the least sign of distress. Hill climbing was excellent, thanks to the engine's high torque and flywheel inertia.
An engine-speed clutch and widely spaced gear ratios do not make for the best in gear changing. Upward changes on the R26 could be made with lightning speed provided some clashing of the dogs was tolerated. Alternatively, noiseless changes could be effected by means of a pause in pedal movement. A slight click accompanied all downward changes. Engagement of bottom gear with the engine idling was almost noiseless; neutral selection was child's play and was indicated by the illumination of a green light in the headlamp shell. Clutch engagement was smooth but because of the high flywheel inertia, the lever was best released gently if a slight lurch was to be avoided.
A wide, powerful headlamp beam made daylight speeds safe on unlit roads after dark. Mudguarding efficiency was above average. At the conclusion of the test which included much hard riding, no oil had leaked from any part of the mechanism.
A fine quality tool kit and good accessibility render maintenance easy. But it is necessary to remove the tank to gain access to the valve adjustments and this involves draining the fuel. However, adjustments are unlikely to be required except after decarboizing the engine. The R26 bristles with attractive features such as quickly detachable, balanced wheels with polished, light-alloy rims, steering and tool box locks and rubber sealing of the tool and battery containers. In its performance, unobtrusiveness, finish and detail design, the R26 cannot fail to engender great pride of ownership.
Engine: BMW 247cc (68 X 68 mm) overhead-valve single with fully-enclosed valve gear, dynamo and ignition equipment. Aluminum-alloy cylinder head. Light-alloy connecting rod; plain big-end bearing. Crankshaft supported by three ball bearings. Compression ratio 7.5 to 1. Pressure lubrication; oil compartment in crankcase, capacity 2.25 pints.
Carburettor: Bing with twistgrip throttle control. Air filter.
Ignition and Lighting: Coil ignition with auto-advance. Noris 60-watt dynamo with automatic voltage control. Bayern 6-volt, 9 ampere-hour battery. Bosch 6.5-inch diameter headlamp with pre-focus light unit and 35/35-watt main bulb.
Transmission: BMW four-speed gear box in unit with engine; positive-stop foot control. Gear ratios: bottom, 22.17 to 1; second, 12.56 to 1; third, 8.49 to 1. Single plate dry clutch incorporated in engine flywheel; fabric friction material. Final drive by enclosed shaft and helical bevel gears. Engine rpm at 30 mph in top gear, 2,630.
Fuel capacity: 3/25 gallons
Tyres: Metzeler 3.25 X 18-inch front and rear
Brakes: 6.25-inch diameter X 1 3/8-inch wide front an rear; finger adjusters.
Wheelbase: 54.5 inches unladen. Ground clearance, 6 inches unladen.
Weight: 330 pounds fully equipped and with full oil container and one gallon of petrol
Price 207 pounds
Braking: From 30 mph to rest, 29 feet (surface dry tarmac)
Turning circle: 13 feet, 6 inches
Minimum non-snatch speed: 15 mph in top gear
Weight per cc: 1.34 pound
Petrol consumption: At 50 mph 80 mpg
Highest one-way speed: 73 mph (conditions moderate side wind; rider wearing two-piece plastic suit and overboots)
Suspension: BMW pivoted-fork front and rear springing employing multi-rate coil springs and hydraulic camping. Two-position manual adjustment for load on rear shock absorbers. Two-position load and trail adjustments on front fork for sidecar duty.