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1990 to 1991 – 3rd Generation Suzuki GSX-R750: More changes, inverted forks
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1990 Suzuki GSX-R750
1990 Suzuki GSX-R750

 

1990 Suzuki GSX-R750L 3rd Generation Suzuki GSX-R750: More changes plus inverted forks

Although this model looks very similar to the previous ’89 model many changes were made. The 1990 Suzuki GSX-R750L was considered possibly the best of the oil-cooled GSX-R750 models. The 1990 Suzuki GSX-R750 featured changes to the engine, suspension, body work, brakes and chassis. This was the first GSX-R to be fitted with inverted forks as standard (USA models retained the conventional forks until 1991), and returned to the bore and stroke dimension of the original long-stroke engine.

The engine returned to the 749 cc engine bore and stroke dimensions of the original long-stroke engine but still maintained the 13,000 rpm redline. It now featured new conrods, lighter pistons, smaller valves than the 1988/89 engine but larger than the 1985-87 engine and used larger carburetors. The new Mikuni model BST38SS “slingshot” carburetors were 38 mm diameter and featured an additional high-speed circuit (circuit was blocked in USA models) and the slide breathers were now divorced from air box. The exhaust system was also changed, gone were the dual silencers and replaced with one stainless steel silencer on the right side and the transmission output shaft was lengthened to accommodate a wider wheel. A new curved oil-cooler design with a large capacity oil pump and oil lines (attached to the oil pan similar to the original 85-87 engines) were installed. Horsepower was up to 115 hp at 11,000 rpm while weight was down to 193 kg.

The frame was changed for 1990 and used some of the features from the ’89 GSX-R1100 frame with the rake was now 25.5 degrees and wheelbase 55.7 inches (1,410 mm). The front suspension now had 41mm inverted forks, the triple clamps (yokes) and handlebars were changed to accommodate the new forks. The rear suspension featured a new shock and swingarm, the rear shock now had a remote reservoir and damping adjustment and the revised swingarm now featured cast ends for the axle adjustment. With the rear wheel widened to from 4.4 inches (110mm) to 5.5 inches (140 mm) but the tire size remained the same. A non-adjustable steering damper was added which attached from the left frame rail to a clamp on the left fork (US models did not receive the damper but the frame had the tapped mounting holes). The rear sprocket carrier and sprocket changed fomr a five to a six-bolt design. The front brake rotors changed from a cross drilled hole design to a slotted design.

The body work changed slightly also with the side vents becoming less rectangular and in a slightly different position. A new fender was also used with the inverted forks (except US).



1990 Suzuki GSX-R750 Specifications

Overall Length: 2,070 mm (81.5 in)
Overall Width: 730 mm (28.7 in)
Overall Height: 1,135 mm (44.7 in)
Wheelbase: 1 420 mm (55.9 in)
Dry Weight: 193 kg (425 lbs)
Engine type: Air and oil-cooled 748 cc inline-4, DOHC, 16 valves. 115 hp/ 11,000 rpm.



 

 

1991 Suzuki GSX-R750
1991 Suzuki GSX-R750

1991 Suzuki GSX-R750M


The most notable feature of the “M” are the faired in headlamps and a slanted nose, both of which were designed to reduce front drag, with distinctive headlight cover and running lights. Also fitted was a new larger seat and new rear body work that featured twin tail lamps. This was the last GSX-R to use the oil-cooled SACS engine (except for US). Internal engine changes included a new valvetrain that used one dedicated cam lobe and rocker arm (finger follower) per valve (previous models used one lobe and one forked rocker per two valves). Valve clearance (lash) was now adjusted with shims (previous models used a screw and nut). The cam duration and indexing changed slightly as well as the porting according to a magazine article. The rear tire width was increased to a 170 mm section width. The gauges also changed to white colored needles (previously amber colored). Horsepower increased by 1 to 116 hp.

Unfortunately, the 1991 Suzuki GSX-R750M gained 15 kg over the 1990 model which negatively impacted its overall performance.

 

1991 Suzuki GSX-R750 Specifications

Overall Length: 2,070 mm (81.5 in)
Overall Width: 730 mm (28.7 in)
Overall Height: 1,135 mm (44.7 in)
Wheelbase: 1 420 mm (55.9 in)
Dry Weight: 208 kg (458 lbs)
Engine type: Air and oil-cooled 749 cc inline-4, DOHC, 16 valves. 116 hp (84.7 kW)/11,000 rpm.


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