Differences between 1981-1986 R80 G/S and 1987-on R100GS.
Some R100GS features apply only to 1991-on R100GS's.
The 1981-1986 R80 G/Ss are much more like R65s and R80STs than they are the R100GS (and 1987-on Paralever R80GS, never imported to North America). It would almost be easier to list the few similarities between the R80 G/S and the R100GS than it is to list their numerous differences.
Though the R100GS gained at least 53 pounds over the R80 G/S, BMW did their homework. That weight came with many, many improvements.
R100GS has: R100GS R80 G/S Difference ------ ------- ---------- More displacement 1000cc 800cc 200cc More power 60hp 50 hp 10hp More torque 56.1 ft-lbs 45.0 ft-lbs 11.1 f/lb More weight 434 lbs dry 381 lbs dry 53 lbs More wheelbase 59.6 in 57.7in 1.9 in More rear suspension travel 180mm 170mm 10mm More front suspension travel 225mm 200mm 25mm Less ground clearance 6.7 in 6.9in -.2 in Less seat height 850mm 860mm -10mm Bigger oilpan bash plate Bigger headlight Bigger battery Bigger gas capacity Bigger oil capacity Bigger fork tubes
Major differences between the two:
Rear wheel (R80 G/S: 18", 3 lugnuts; R100GS: 17", 4 lugnuts) Starter motors (R80 G/S: Bosch, R100G/S: Valeo) Forks (R80 G/S: 36mm BMW; R100GS: 40mm Marzocchi) Exhaust material (R80 G/S: black, rusts; R100GS: stainless steel) Centerstand design (R100GS centerstand pedals are curved out) Electrical components (Arranged differently under the gas tank, basic charging system is the same however.) Gas tank design (R80 G/S: longer, one petcock, 5.1 gal; R100GS: knee depressions, two petcocks, 5.8 gal) Master cylinder (R80 G/S 1982 - 1986: 12mm; R100GS: 13mm) Front brakes (?) (R100GS brakes don't suck as much as R80 G/S brakes) Controls (R80 G/S: old-style; R100GS: K-style) Final drive ratio (R80 G/S: ?; R100GS: ?)
Things R100GS has that R80 G/S doesn't:
Paralever Windscreen/headlight fairing ('91-on) "Roo" bars ('91-on) Tachometer ('91-on) Oil cooler Crossover tube in header pipes Right-side fuel petcock Sidestand reinforcement Centerstand bash plate (PD option?) Standard accessory socket
Tubeless tires Thicker upper triple clamp K-style controls Vented (no hose) gas cap Fuel solenoids (CA models) Plastic engine oil dipstick Updated clutch spline material
Things the R80 G/S has that the R100GS doesn't:
A '/' between the G and the S At least 53 fewer pounds Stock kickstart
This omits the differences between the PD kits, but the most notable one is that the R80 G/S's seat is attached to its PD luggage rack. To get under the seat, the rack must be removed too. The R100GS PD solo seat pops off separately from the rack.
Also, the R80 PD gas tank is steel, holds 8.9 gallons and puts the gas farther back than the R100GS PD tank. The R100PD tank holds 9.3 gallons, is fiberglass and has a handy locking compartment.
Though the G/S has a slightly higher listed seat height than the GS, in practice, most people have noticed that the G/S seems lower. But the experienced vertically challenged will immediately point out that the 53 pound difference is what makes the G/S an easier bike to handle, not the negligible difference in seat height.