Adler M 250
| Eagle | |
|---|---|
 MB 250 from 1954 |
|
| M 250 to MBS 250 | |
| Manufacturer | Adlerwerke |
| Production period | 1954 to 1958 |
| class | motorcycle |
| Motor data | |
| Two-cylinder two- stroke engine | |
| Displacement (cm³) | 247 |
| Power (kW / PS ) | 11.8 / 16 at 5600 rpm to 13.2 / 18 at 6200 rpm |
| Top speed ( km / h) | 116/126 |
| transmission | 4 courses |
| drive | Chain drive |
| Wheelbase (mm) | 1225-1335 |
| Seat height (cm) | 78 |
| Empty weight (kg) | 145-170 |
The Adler M 250 model is a motorcycle made by Adlerwerke in Frankfurt am Main.
Model history
The forerunner of the Adler M 250 was the Adler M 200, which was built in parallel until 1955. The last models of the M 250 and MB 250 were the Favorit and Sprinter in 1957 . In 1958 the motorcycle production of the Adlerwerke ended. In addition to the road, Adler built the 250 as Adler-Sixdays for reliability rides, the special Adler Motocross machine with initially 20 hp at 6400 rpm and the RS 250 racing motorcycle with initially 26 hp, the latter with both air and water-cooled engines. After production ended, the RS was further developed by racing mechanics and drivers in the Adler works, most recently with an engine output of 36 hp at 8700 rpm.
engine
The engine is a transversely installed air-cooled two-cylinder two-stroke engine with 180 ° crank offset and reverse scavenging . The compression ratio of 5.75: 1 on the MB 250 S was increased to 6.6: 1 in order to increase performance; The 18 hp engine of the MB 250 S has modified exhaust ports and forged pistons 16 grams lighter with only two piston rings instead of the 206 gram cast 3-ring pistons of the 16 hp engine. The mixing ratio of oil and gasoline is 1:25.
The MB 250 is equipped with a 6-volt electrical system. The spark plugs had a heat value of 225 to 240 - according to the Bosch system - and an electrode gap of 0.6 to 0.7 mm; the 18 hp engine requires 280mm spark plugs.
The alternator, the ignition system each with two breakers, capacitors and ignition coils are encapsulated. The rotor sits on the crankshaft. The voltage regulator is attached to the right. The horn is mounted on the left in a sheet metal flap, roughly below the driver's seat.
transmission
The engine, clutch, gearbox and alternator of the M 250 to Favorit model series are combined in a common housing. The claw-shift gearbox has a primary drive with helically toothed spur gears. It has foot switching with the switching scheme 0-1-2-3-4 (idling at the bottom, indicated by a signal lamp), based on the one-armed gear lever. Some of the motorcycles were also built with a rocker switch . The oil content of the gearbox is 1.2 l SAE 20 engine oil .
landing gear
The Adler M 250 and the following series had a double tube frame suitable for sidecars, a front fork with a pushed short swing arm and, until 1956, a straight travel suspension with hydraulic damping and 50 mm travel. Initially, the bars of the front fork reached under the handlebars and were connected with two fork bridges; the fork had coil suspension and friction dampers. From the end of 1953, Adler built the MB fork with coil springs and hydraulic damping; the fork tubes of this fork, also known as the "rocker arm fork", ended below the steering head and were connected there with a cast fork bridge. The steering head was placed higher to allow tall drivers a comfortable seating position. All M and MB models have an adjustable friction steering damper. The brake anchor plate was supported on the fork with an additional handlebar to absorb the braking torque. This suppressed the "straightening up" of the motorcycle when braking. The rear swing arm with spring struts was also new to the Favorit and Sprinter. The rear suspension of all models could be set by hand for solo or pillion rider use. Due to the rear swing arm, the wheelbase has been extended by 75 mm from 1260 mm to 1335 mm compared to the MB 250; the M 250 had a wheelbase of 1225 mm. The tire size of the Adler Sprinter is 3.25–18 front and rear, while the Adler-Favorit is 3.25–16 at the front and 3.50–16 at the rear. The full hub brakes have a drum diameter of 180 mm and a brake pad width of 30 mm.
Furnishing
The motorcycles were available in black or green and, most recently, blue. The on-board tools made of chrome-vanadium steel were housed in a box in the tank on the models before 1957, then in a box to the right of the rear wheel. Older M-tanks have two caps. All M and MB models have an adjustable handlebar. In the course of the approximately five-year construction period, there were five variants in addition to the models for sports, which differed slightly in terms of equipment and performance, and a 280 cc export version MB 280 for Austria with 18 hp. The models M 250, MB 250 and MB 250 S with a raised exhaust system were available for an extra charge.
Adler Sixdays
The Adler-Sixdays off-road motorcycle, known internally as the MBS 250 G, was derived from the Adler-Sprinter, with the engine remaining the same as in the production model. Otherwise, the machine differs primarily in its greater ground clearance, achieved by a 19-inch front wheel with 3.00–19 tires and a modified front fork with additional long-stroke suspension struts in front of the fork tubes. At the rear it stayed with the 18-inch wheel, but with 3.50-18 off-road tires. Otherwise, the machine had a high handlebar, raised mudguards, a tool box on the tank, a protective grille in front of the headlight against falling rocks and pipe supports that protected the engine from damage. The single-port exhaust was pulled up and left no more space for the battery box, which is why the battery was moved into the lamp housing. A special feature that could only be used in competition was an oil tank from which oil dripped onto the open drive chain. The gearbox had a shorter gear ratio than the standard version, so that the top speed was around 100 km / h.
At the 31st six-day race in Garmisch-Partenkirchen in 1956, the three Adler works riders won three gold medals with the new motorcycle. Nevertheless, interest in Adler-Sixdays, which was offered for sale for DM 2,315.00, remained low. Only 20 pieces were built.
Adler RS 250
At the instigation of Helmut Hallmeier sen. and Helmut Hallmeier jun. Adler developed the racing machine RS 250 from September 1953. The condition was to largely use serial parts of the M 250 in the design and thereby keep costs as low as possible.
The engine received an intake duct that was increased in height and two Amal carburetors with a diameter of 24 mm. The standard light alloy pistons with three piston rings were exchanged for pistons from Mahle with two rings. The RS engine also had cylinder heads with increased cooling fins, a lighter and finely balanced crankshaft, a trough-shaped combustion chamber to increase compression (8.5: 1 instead of 6.6: 1) and Bosch magneto ignition instead of battery ignition. The power increased from 18 hp at 6200 rpm to 26.6 hp at 7500 rpm.
Furthermore, the RS received a lightweight double tube frame with a single top tube and a rear swing arm, as it was only later adopted into series production. The front fork with pushed short swing arm was similar to the standard version. Otherwise, a 16-liter aluminum tank, a seat and a rear fairing belonged to the racing model with a weight of about 100 kg. Among other things, a kick starter was omitted to save weight. The top speed was over 160 km / h, depending on the gear ratio.
This air-cooled Adler 250 RS was first used at the Dieburger Dreiecksrennen on April 11, 1954. Hallmeier jun. won the race over 25 laps or 125 km in 1: 04: 01.2 hours ahead of DKW driver Karl Lottes . That corresponded to an average speed of 117.1 km / h. Hallmeier drove his fastest lap in 2: 30.9 minutes or 119.3 km / h. In the 1954 Solitude race over 12 laps (138 km), he finished third behind NSU works drivers Werner Haas and Rupert Hollaus , around 4½ minutes behind and an average speed of 126.7 km / h.
After this and other successes, Adler decided to build ten RS 250s that were offered to private drivers for sale. The machine costs DM 3,950.00, about twice as much as the standard Adler M 250 S.
In the races of the 1954 season there were also several breakdowns of the Adler machines, in particular due to insufficient cooling. Thereupon it was switched from air to water cooling, with two separate water coolers, which were mounted high on the front frame loop. A water pump was not needed. In addition, the improved version received carburettors with a 28 mm diameter and the compression was increased, so that the output rose to 32 hp at 8200 rpm. (For comparison: the output of the NSU Sportmax, which can also be bought for 4,000 DM, was 28 hp in 1955.)
In the course of further development, the RS was also driven with fairing, initially with the so-called dolphin fairing, which left the front wheel open, and then with full fairing. The factory-supported use of the Adler racing motorcycles ended in 1956. After that, the drivers were left to their own devices and their mechanics, and yet Dieter Falk (* 1930) from Freudenberg (Siegerland) was German champion in the class up to 250 cm³ and fifth in the TT in 1958 the Insel of Man in the lightweight class.
The Adler RS 250 was still driven into the 1960s, most recently with around 36 hp at 8700 rpm, an enlarged radiator, six-speed gearbox and front double duplex brakes .
Technical specifications
| Parameters | MB 250 | MB 250 S | sprinter |
|---|---|---|---|
| engine | Two-cylinder two-stroke | ||
| Displacement | 247 cc | ||
| Bore × stroke | 54 × 54 mm | ||
| compression | 1: 5.75 | 1: 6.6 | |
| Power at 1 / min | 16 hp (11.8 kW) at 5600 | 18 hp (13.2 kW) for the 6200 | |
| cooling | Air cooling (airflow) | ||
| Electrical system | 6 V, 60/90 W. | ||
| transmission | 4-speed with foot switch | ||
| frame | Double tube frame, suitable for sidecars | ||
| Front suspension | Short arm swing arm, hydraulically dampened | ||
| Rear suspension | Straight, hydraulically damped |
Swing arm with spring struts, hydraulically damped |
|
| wheelbase | 1260 mm | 1335 mm | |
| tires | 3.25-16 | 3.25-18 | |
| Brakes | Drum brakes | ||
| Empty weight (without driver) | 145 kg | 170 kg | |
| maximum weight allowed | 295 kg | 320 kg | |
| Tank capacity | k. A. | 15 l | |
| Top speed | 116 km / h | 126 km / h | |
The tire sizes are front / rear for the Sixdays model 3.00–19 and 3.50–18, for the motocross model 2.75–19 and 3.00–19.
literature
- Dieter Jorzick, Johann Kleine Vennekate: Adler motorcycles . 2nd edition, Johann Kleine Vennekate, Lemgo 2007, ISBN 978-3-9804987-7-7 .
Web links
Individual evidence
- ↑ Ernst Leverkus: The great motorcycles of the 50s . Motorbuch Verlag, Stuttgart, 8th edition 1993, ISBN 3-87943-849-8 , pp. 31-35.
- ↑ a b Adler Schwinge advertising brochure , issue 4/56.
- ↑ Adler index.htm. In: www.historicmotorcycle.org.au. Retrieved June 26, 2016 .
- ↑ Wheelbase according to the in-house magazine "Adler Schwinge". Jorzick / Kleine Vennekate name 1350 mm.
- ↑ a b Jorzick, Kleine Vennekate: Adler Motorcycles . Verlag Kleine Vennekate, Lemgo 2007, ISBN 978-3-9804987-7-7 . Pp. 46-89.
- ↑ Jorzick, Small Venne Kate: Adler motorcycles . Verlag Kleine Vennekate, Lemgo 2007, ISBN 978-3-9804987-7-7 . Pp. 94-101.
- ↑ Jorzick, Small Venne Kate: Adler motorcycles . Verlag Kleine Vennekate, Lemgo 2007, ISBN 978-3-9804987-7-7 . Pp. 101-108.
- ^ Yearbook of International Motorsport. ADAC 1954, p. 189.