Press the starter and the whole bike shakes and rocks like a World War II fighter just firing up, coughing, spluttering and struggling to get going. Once the starter has had its tussle with the big twin engine they do sort it all out and agree to get on with the job, the twin Bing carburettors fire a quick squirt of petrol into their respective cylinders and the engine settles into a burbling tick over. Even then the whole bike joins in with the rhythm, dancing away in time with the exhaust note as if alive, the side ways forces of the boxer engine creating a strange handle bar movement in the lower rev range.
Well balanced, and easy to get the best out of on just about any terrain, the bike is a doddle to get along with, its thumpy and willing engine happily trudging down green lanes or speeding along on the highway. Serious off-roading is best left to those svelte single cylinder machines with a good deal more ground clearance, less engine and all up weight, the Beemer can do it, but you probably wouldn’t want to be too close to it when thing go wrong which of course they can and do so easily on the rough. Where the G/S comes into its own is out on the open road, power is plentiful, smooth and easily controlled. Once the lumpy gearbox has been dialled into the brain, the G/S is a delight to ride, each gear selection can be notchy if the correct throttle-clutch ratio and timing isn’t used, but once this has been mastered clutch free shifts are a reality. Not that gear shifts are common, the torquey, and well fuelled engine will easily, and strongly, pull from around 30mph in top gear so, for most corners and obstacles, it a case of leaving it in full auto mode and enjoy the ride.
Down shifts can be more difficult, with so much engine mass spinning around getting that and the rear wheel in sync throughout the process is a real art form, which, once mastered, is addictive. The shaft drive imparts its will upon the rear end too, these were the early days of such devices and to say the idea wasn’t fully sorted would be an understatement, any heavy handed throttle inputs or down shifts has the back end trying to rotate around the gear box as the pinions transfer the power through 90 degrees and out to the wheel. Get too enthusiastic and rear wheel hop is also unavoidable, an effect not too bad to deal with when upright but, all to unwanted at any angle of lean. This effect isn’t as bad as other more road biased machines for m the BMW stable as in an effort to reduce weight for the G/S around 8kgs was shaved off from various reciprocating components within the clutch, this in turn reduces to mass and does make for a smoother feeling action although still nowhere near the silky operation enjoyed on bikes from the big four.
Despite the look and suggested bulk the R80G/S is in fact a lively beast capable of lofting the front wheel in the first two gears and leaping up all kinds of inclines like a youngster. Braking could be better and is the one area where the Beemer could be improved particularly on the tarmac where speeds and grip are generally higher than off road. Despite having a powerful twin-opposed-piston Brembo caliper it is let down by the size of the disc it has to grab and also the weight of the bike behind it. In reality, a twin disc set up or a much larger diameter disc is required to keep the whole plot in check with authority.
At low speed the Boxer engine acts like a gyroscope keeping the bike upright and making feet up u-turns, or full stops at traffic lights and junctions, a doddle once confidence has been gained. The secret is to not blip the throttle when at low speed as or at a complete standstill, doing this has the bike swinging alarmingly to one side as the huge crankshaft spins up from its low revving slumber and the rest of the bike reacts to its spinning mass. Simply leave the throttle well alone when at rest and enjoy this stunningly well-balanced machine to the full. A trials bike like, lock to lock, steering arc has the big bike doing feet up u-turns in the tightest of back roads making for effortless rambling around. Throwing the bike around twisty bends couldn’t be any easier thanks to the low slung engine and wide handle bars, while at speed amore conventional superbike stance is the order of the day. The big Beemer responding to small inputs through the bars and pegs and flicking from side to side with great enthusiasm in a manner not at all in keeping with the image it portrays.
BMW R80G/S Model History
The start of the G/S, or Gelande Strasse project ( Gelande is the German for off road and Strasse means street) can be traced as far back as 1975 when suspension expert Rudiger Gutsche built his own enduro machine based around the road going R75. Later versions of this privately built Beemer featured the single sided Monolever rear suspension initially developed for the new K series but first seen in production on the G/S. The main advantages of this design being its torsional strength and light weight, having just the one main arm that also doubles as the drive shaft tube, supported by a single shock absorber. Fast rear wheels changes were an added extra with the design, however the rear swing arm that gave the G/S its distinctive look was actually dropped for the pukka Paris-Dakar race bikes as the BMW team used a more conventional swing arm set up for increased durability in the unforgiving and tough world of desert racing.
The launch of the R80 G/S wasn’t totally unexpected after all, the Boxer engine in its various guises had been successful in a whole host of off road disciplines during the 70’s. What was surprising was the capacity chosen as the first G/S model, being 800cc made it the largest off-road machine by a good margin, until that point the Yamaha XT500 laid claim to that title. Like the Yam thumper the BMW displayed pleasing on tarmac habits as well as a capable, if a little limited, off road ability. Unlike the big Yam the R80 G/S had a set of specially developed multi purpose tyres by Metzeler that enabled its go anywhere attitude to be used to the full. Trail tyres of the period were rated no higher than the P speed range which, with a sustained top speed of 93 mph clearly wouldn’t have been suitable for the G/S with its treble figure to speed. The challenging work carried out by Metzeler set a trend that others soon followed, effectively opening up the world of the trailie into a whole new speed and ability range.
Produced between 1980 and 87, 21,864 G/S models were built in total making it a great success for the BMW. It even spawned a roadster version, the R80ST introduced in 1983. This was little more than an ill-conceived parts bin special that used much of the G/S bodywork and cycle parts running on wire wheels when the rest of the world had switched to cast alloy items. Although a fine handling machine, it was underpowered when compared to similar capacity machinery from the big four Japanese manufacturers. Needless to say, despite the type receiving good reviews when launched, this model wasn’t the success that the G/S had been and with few sold, the type disappeared out of the model range.
In latter part of 1987 the G/S was replaced by the Paralever GS model, available in both 800cc and 1000c versions. This new machine was considerably bigger all round and featured an all new rear end. A traditional shaft drive causes the rear to sit up under acceleration and squat off the throttle, this effect is undesirable but these forces can be designed out , how ever to do this effectively the swing arm would need to be unfeasibly long, around 1700mm in the case of the Boxer engine. The Paralever however, with its two flexible joints along the length of the swing arm, allow the wheel to behave as if it were situated within a much longer swing arm and the negative effect of the final drives torque reaction is reduced by around 70%. This complex arrangement, made entirely of cast aluminium, is actually no heavier than the steel swing arm it replaced.
BMW R80G/S Timeline
1980 BMW R80G/S – Chassis number 6250001
Take the R80 engine and wrap it up in an R65 chassis with long travel suspension and you have the unlikely but, none the less, successful G/S range
1981 – Chassis number 6251499
This was the first real year for the G/S range, it coincided with the type win in the Paris –Dakar race of that year and this in turn led to the maximum impact possible for the range. It sold over 6000 units in the first year of production.
1982 – Chassis number 6255879
Electric start now fitted a standard while the rear rim received a wider section
1983 – Chassis number 6258246
The G/S remained unchanged for this year
1984 – Chassis number 6281212
A new gas rear shock with remote reservoir is fitted while a limited edition Paris-Dakar model is also introduced.
1985 – Chassis number 6283357
Having seen few changes since its introduction for this year the G/S got a revised engine. New heads and rockers reduced noise while improvements were made in the transmission.
1986 – Chassis number 6286767
A new colour scheme and a different shape seat marked the only changes to the G/S for the next two years
1987 – Chassis number 6291006, ends 6292522
The last of the R80G/S models
1988
The G/S loses its slash and becomes the Paralever R80GS and 100GS complete with lightweight Marzocchi forks. The older design lived on as the German market only R65GS, visually identical to the previous G/S, but with a mere 27bhp on tap, this under powered machine wasn’t popular.
Paris–Dakar the inspiration behind the design
Almost as soon as the G/S was launched it received a great push with Frenchman Hubert Auriol winning the 1981 Paris-Dakar rally on a race prepared version. Auriol and BMW repeated this feat again in 1983 on a 870cc G/S and finishing second the following year behind team mate and three times world motocross champion Gaston Rahier. BMW withdrew their official works team from the event following the death of organiser Thierry Sabine in 1986 but still continued to develop privateer machinery to good effect, privateer riders continuing to make themselves known among the leading riders throughout the next couple of years.
BMW R80G/S Specifications
- Engine – air-cooled horizontally-opposed 4-stroke twin
- Capacity – 797cc
- Bore & stroke – 84.8 x 70.6mm
- Compression Ratio – 8.2:1
- Carburetion – Bing 32mm CV
- Max Power – 50bhp @ 6500rpm
- Torque – 41.8ft lb @ 5000rpm
- Ignition – Bosch electronic
- Transmission – 5-speed wet clutch shaft final drive
- Frame – steel tube cradle
- Suspension – 36mm telescopic forks, monolever rear
- Wheels – 3.00 x 21 4.00 x 18
- Brakes – 260mm disc twin-opposed-piston Brembo caliper, 200mm single leading shoe drum
- Wheelbase – 1465mm
- Weight – 173kgs
- Fuel capacity – 19.5 ltrs (Dakar tank 32 ltrs)
- Top speed – 104mph
BMW R80G/S Gallery
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