.

BMW R 80G/S Paris Dakar

.  

Make Model

BMW R 80G/S Paris Dakar

Year

1985
Production 200 Units

Engine

Four stroke, two cylinder horizontally opposed Boxer, pushrod operated 2 valves per cylinder.

Capacity

797.5 cc / 48.7 cu in.
Bore x Stroke 84.8 x 70.6 mm
Cooling System Air cooled
Compression Ratio 9.2:1

Induction

2 x Bing constant depression carburetors

Ignition 

Battery ignition 
Alternator Bosch 12 V/280 W
Spark Plug Bosch W 7 D / Beru14-7DU / Champion N9YC
Starting Electric & Kick

Max Power

37 kW / 50 hp @ 6500 rpm

Max Torque

56.7 Nm / 5.8 kgf-m / 41 ft lb @ 5000 rpm
Clutch Dry single plate, with diaphragm spring

Transmission 

5 Speed 
Final Drive Shaft
Gear Ratio 1st 4.40 / 2nd 2.86 / 3rd 2.07 / 4th 1.67 / 5th 1.50:1
Rear Wheel Ratio 1:3.20
Frame Double loop tubular frame with bolt on rear section

Front Suspension

Telescopic hydraulic forks.
Front Wheel Travel 200 mm / 7.8 in

Rear Suspension

Monolever swinging arm.
Rear Wheel Travel 170 mm / 6.6 in

Front Brakes

Single ∅260mm disc

Rear Brakes

200mm Drum

Front Tyre

3.00 - 21

Rear Tyre

4.00 - 18
Dimensions

Length  2230 mm / 87.7 in

Width      820 mm / 32.3 in

Height   1150 mm / 45.2 in

Wheelbase 1465 mm / 67.6 in
Ground Clearance 175 mm / 6.88 in
Seat Height 860 mm / 33.9 in

Wet Weight

205 kg / 452 lbs

Fuel Capacity 

32 L / 8.4 US gal
.  

The R80GS earns its place as being one of the world's biggest and fastest off-road bikes. It is very good on the road but not so good on the dirt. The GS stands for Gelanden Strasse or street scrambler. BMW call it 'a hobby bike, a two-wheeled Range Rover' and the comparison is appropriate. It is not a serious dirt bike but it is one of the best all-purpose bikes ever built. Suitably beefed-up factory versions have won the gruelling Paris to Dakar rally on three occasions. In stock production form, the GS80 has proved a popular choice for riders exploring the world on long distance trips across continents with all types of terrain. It is a 100 mph road bike that can cope with the rough stuff.

 The machine is an imaginative mix of parts that were already available on other BMW bikes, spiced with some adventurous engineering. An example is BMW's patented 'mono-lever' rear suspension, a one sided swing-arm with a single gas shock unit. In effect, it is half a swing-arm, but BMW's engineers made it both lighter and 50 per cent stronger than a conventional assembly. The rear wheel is held on by three bolts, there is nothing you could call an axle.

The wheel bearing is big, the crown wheel housing is internally stressed since it has to carry the full loads of the back wheel with 6.7in of travel available, and the whole rear suspension works admirably. Quick wheel changing is obviously a bonus.  The front suspension consists of leading axle forks offering a luxurious 7.9in of travel. The bike is tall and needs to be for reasonable ground clearance (8.58in). The steering is quick and the throttle response lively. The whole machine is light and nimble with plenty of power and very good brakes. Like all flat twin BMWs, it has a low centre of gravity, so the bike can be chucked around with abandon.

The dual-purpose, knobbly tyres are S-rated and give wonderful grip. The engine is an updated variant of the R80 road bike endowed with typical BMW performance - bags of torque and a wide spread of power - plus some dual-purpose innovations. The bike has a light-weight clutch and flywheel for quicker throttle response, and some low gearing; necessary for a dirt bike but lots of fun anywhere since it helps the GS to wheelie easily. On the open road it will hold 100 mph for as long as the rider can face sitting up so high and exposed against the wind. Unfortunately what makes it good on the tarmac tells against it on the dirt. The bike is just too big and too powerful. Fully gassed (4.3gal) it weighs 4101b, fine for a road bike but a little heavy for serious off-road use. In addition there is the long wheelbase, the unsprung weight of the driveshaft and two horizontal cylinders that stick out a long way, all factors that conspire against its dirt ability.

These are not problems when traction is positive on firm ground but in mud and real rough stuff, the bike bogs down far too easily.  The R80GS is best used as a cross-country bike, sticking mainly to proper roads but taking the odd short cut and back road where necessary. Above all else, the bike is a lot of fun to ride; it is a functional, practical, rugged and reliable all-rounder. Recently, various BMW importers have released Paris-Dakar replica versions of the bike as a tribute to one of the world's most successful desert racers.

Source of review : The Worlds Fastest Motorcycles by Michael Scott & John Cutts

The R80G/S (G for Gelände "offroad" in German S for Strasse "street") was the first large displacement multisport bike on the market. The G/S was fitted with a 797.5 cc (48.67 cu in) BMW type 247 engine, which is a flat-twin (boxer) sometimes known as an airhead.

The engine, which was fitted into an R65 frame, was a modified version of that fitted to the R80/7, featuring Nikasil cylinders, electronic ignition and a lighter flywheel.[2] At the rear the bike had a new design combined single-sided swingarm and drive shaft – called a monolever with the rear dampening provided by a single shock absorber. The monolever was stiffer and lighter than the design fitted to previous models, and was subsequently fitted to other BMW motorcycles. It was a sealed suspension lever with the driveline inside the lever filled with oil to lubricate the shaft and parts. The single sided swing arm enabled the rear wheel to be removed easily with the bike on the center stand. It differs from other BMW road bikes of the same era due to its lighter weight, longer suspension travel, and large 21 inch front wheel.[3] The bike gained popularity with adventure-seeking travellers after having won the Paris-Dakar ralley several times

. BMW offered numerous optional parts including a 32-litre (7.0 imp gal; 8.5 US gal) fuel tank with Gaston Rahier's signature, a solo seat, stainless exhaust and a larger battery meaning that for the first time a true adventure travel motorcycle could be purchased directly from a manufacturer. The market it created spawned many aftermarket motorcycle accessories, such as larger fuel tanks and panniers.

The R80G/S was developed for BMW by engineer Rüdiger Gutsche, a successful competitor in the International Six Days Trial on his specially adapted R75/5. In 1981, Hubert Auriol, riding a R80G/S prepared by German company HPN Motorradtechnik, won the Paris-Dakar Rally.[6] He repeated his success on an 870 cc version of the R80G/S in 1983.[5] Gaston Rahier won the Dakar on a R80G/S in 1984, and then again on a larger 1,000 cc engined R80G/S in 1985. To commemorate their success, BMW launched the R80G/S Paris-Dakar special edition which featured a 7 imperial gallons (32 l; 8.4 US gal) fuel tank, fitted with dual petcocks and signed by Gaston Rahier.

In 1986, the R80G/S was joined by the R100GS, which had a larger capacity 980 cc engine and an updated suspension and drive unit called a Paralever. In 1987, production of the R80G/S ended and was succeeded by the 650 cc R65GS, which used the same monolever suspension and drive, and the R80GS, which retained the G/S engine but used the newer Paralever drive.