BMW R12 and R17
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Manufacturer | BMW Motorrad |
---|---|
Production | 1935–1942 |
Assembly | Munich,Germany |
Predecessor | R11 |
Engine | 745 cc (45.5 cu in)Side-valve4-strokeflat twin,Overhead valve4-strokeflat twin |
Bore/stroke | 78 mm × 78 mm (3.1 in × 3.1 in) |
Compression ratio | 5.2:1 |
Top speed | 110 km (68 mi) - 120 km (75 mi)[1][2] |
Power | 18 hp (13 kW)[1] |
Ignition type | Magneto or battery ignition |
Transmission | Manual |
Tires | 3.50×19 |
Dimensions | L:210 cm (83 in) W:90 cm (35 in) H:94 cm (37 in) |
Fuel capacity | 14 L (3.1 imp gal; 3.7 US gal) |
Fuel consumption | 3.5–4 litres per 100 kilometres (81–71 mpg‑imp;67–59 mpg‑US)[1] |
TheBMW R12andR17areflat-twin enginemotorcyclesmade byBMW Motorradfrom 1935 through 1942. They were developed in 1935 based on theR7concept of 1934.[3][4]A few hundred R17s were made, ending in 1937, while the R12 continued through 1942, with a total of 36,008 produced.[5]
R7 concept
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/0/01/BMW_R7_profile.jpg/220px-BMW_R7_profile.jpg)
The BMW R7 was conceived in 1933 by engineer and designerAlfred Böning,with anArt Decomathematical geometric basis of his design.[6]Only one R7 was ever made, which Böning disassembled and stuck away with design plans in a BMW warehouse. It was discovered more than seventy years later, in 2005. Hans Keckeisen in Munich began a restoration on behalf of theBMW Museum,completed 2012.[7]After appearing in European bike shows, restored 1934 R7 was first shown in the US at thePebble Beach Concours d'Elegance.
Böning's new hydraulic fork design of the 1934 R7 went into production the following year, in the 1934 R12 and R17.[5]
R12 and R17
[edit]On 14 February 1935, BMW presented the R12 together with the R17 on the German Automobile Exhibition in Berlin for the first time, being a direct successor to theBMW R11.[8]This and the R17 were the first in the world being produced withhydraulically damped telescopic forks.[9]By 1942, the total number of BMW R12 motorcycles manufactured was 36,000.[2]For military purposes, the single carburetorEinvergasermotorwas only available for the R12.[10]
Engine
[edit]The engine, designatedM 56 S 6or212,was a twin-cylinder boxer configuration -four strokewith aflatheaddesign.[1]The BMW R12 with two carburetors used a battery and coil ignition, while R12s with a single carburetor used a magneto ignition, capable of working independently from the battery.
Drive
[edit]The BMW R12 had a four-speed manual gearbox, operated by a hand shift lever on the fuel tank's right side. Several detail variations were seen in production. In common with mostBMW Motorcycles,final drive was via shaft, with thedrive shafton the right side of the motorcycle.
Suspension and brakes
[edit]Front suspension used a telescopic fork, while the frame was rigid with an un-sprung rear end supporting the final drive and a sprung seat for the rider. The R12 useddrum brakesfront and rear. Many R12's were equipped with asidecarattached to the motorcycle's right side.
Specifications
[edit]R12 | R17 | |
---|---|---|
Years | 1935–1942 | 1935–1937 |
Number produced | 36,008 | 434 |
Engine | M56 S6 (single carburetor)[1]or M56 212 (two carburetors)[2] |
M60 (two carburetors)[5] |
Type | Side-valve4-strokeflat twin | Overhead valve4-strokeflat twin |
Displacement | 745 cc (45.5 cu in) | 736 cc (44.9 cu in) |
Bore × stroke | 78 mm × 78 mm (3.1 in × 3.1 in) | 83 mm × 68 mm (3.3 in × 2.7 in) |
Compression ratio | 5.2:1 | 6.5:1 |
Fuel system | Sum CK 25 mm or 2 ×Amal6/406/407 23.8 mm |
2 × Amal 76/424 1-inch |
Ignition | Magneto or battery | |
Transmission | 4-speed, shaft drive | |
Suspension | Front: telescopic fork Rear: rigid | |
Tires/wheels | Front & rear: 3.5×19/3×19 | |
Brakes | Front & rear: 200 mm drum | |
Frame | Twin loop, pressed steel | |
Power | 18 hp (13 kW) or 20 hp (15 kW) (2 carburetor) | 33 hp (25 kW) @ 5,000 rpm |
Top speed | 110 km/h (68 mph) or 120 km/h (75 mph) (2 carburetor) | |
Dry weight | 162 kg (357 lb) | 165 kg (364 lb) |
Fuel capacity | 14 L (3.1 imp gal; 3.7 US gal) |
Surviving motorcycles
[edit]A BMW R12 is in theMuseum of Military HistoryinVienna,in its original camouflage.[11]In 2018, an American company created a modifiedBMW R nineTwith a close resemblance to the original R7, showing the R7-inspiredcustomat several shows and museums, and selling kits or complete bikes to the public.[12][13]
See also
[edit]References
[edit]- ^abcde"BMW R 12 Einvergaser"(in German). BMW Archive Group. Archived fromthe originalon 19 August 2014.Retrieved3 March2015.
- ^abc"BMW R 12 Zweivergaser"(in German). BMW Group Archive. Archived fromthe originalon 8 March 2015.Retrieved3 March2015.
- ^"BMW R 12 Schnittzeichnung der Telegabel"(in German). BMW Group Archive. Archived fromthe originalon 19 August 2014.Retrieved3 March2015.
- ^Cupler, Justin (August 21, 2012),"1934 BMW R7",Total Motorcycle
- ^abcFalloon, Ian (2015),The Complete Book of BMW Motorcycles: Every Model Since 1923,Motorbooks, pp. 44–52,ISBN978-1627887649
- ^Sánchez, Miguel (November 13, 2018)."Art Deco: BMW R7 Nmoto Nostalgia".La Escudería(in Spanish).Retrieved2019-11-11.
- ^"Inside the Nmoto Nostalgia: BMW R nineT Meets R7".Ultimate Motorcycling.2018-12-08.Retrieved2019-11-11.
- ^"BMW präsentiert bei den Modellen R 12 und R 17 die weltweit erste hydraulische Teleskopgabel"(in German). BMW Archive Group. Archived fromthe originalon 27 March 2014.Retrieved3 March2015.
- ^Setright, L. J. K.(1977).Bahnstormer: The story of BMW Motor cycles.Transport Bookman Publications. p. 47.ISBN0-85184-021-3.
- ^Zeyen, Wolfgang; Leek, Jan (2004).BMW: die Motorräder seit 1923(1. Auflage ed.). Stuttgart: Motorbuch Verlag. pp. 71–88.ISBN3-613-02401-2.
- ^Rauchensteiner, Manfried (2000).Das Heeresgeschichtliche Museum in Wien(in German). Graz: Styria. p. 92.ISBN978-3-222-12834-9.
- ^Stecher, Nicolas (May 6, 2019)."The Nmoto Nostalgia Is a Modern Take on An Iconic Motorcycle".Maxim.Retrieved2019-11-11.
- ^Ewing, Mark (December 4, 2018)."NMOTO Recreates The Sexiest BMW Motorcycle Ever, The Mythological R7".Forbes.Retrieved2019-11-11.