Power 60hp @ 8,500rpm (rear wheel)
Top speed 112mph (period test)
Engine 748cc, (65mm x 56.4mm) air-cooled, DOHC, 8-valve inline 4-cylinder
Transmission 5-speed
Weight 511lb (half tank)
Price then/now $2,195 (1977)/$2,000-$4,500
When Suzuki launched its first 4-cylinder, 4-stroke motorcycle, the company knew it had to build a winner. There was no going back: the days of 2-stroke motorcycles on U.S. roads were coming to an end, and the new bike was running dangerously late against the competition. Honda’s 750 Four, which created the inline quad category, was already seven years old: the hot-rod Kawasaki Z1 had been on the market three years; Yamaha had its DOHC 750 triple — and the mighty XS1100 was waiting in the wings.
Spotting a gap in the market, Suzuki created a machine that was more technically advanced than the class-defining CB750 (by featuring double overhead camshafts) in a more popular capacity class than the Z1/KZ (750cc vs 900cc), and sportier than the shaft-drive Yamaha.
As early as 1974, selected U.S. Suzuki dealers had been able to see and ride a prototype DOHC 750, with their feedback incorporated into the production bike. So when the first GS750s arrived in the U.S. in late 1976, the formula had been enhanced and refined.
Like Kawasaki, Suzuki combined its 2-stroke expertise with current 4-stroke thinking. They designed a short-stroke, DOHC, 8-valve engine with a ball-and-roller bearing bottom end and built-up crankshaft. The short stroke allowed a bigger bore and larger valves for more revs and more power. The bottom end followed 2-stroke practice and proved so strong that drag race engine builders are still using GS-based crankshafts 40 years on!
From the center of the crankshaft, a roller chain with automatic tensioner turned dual overhead camshafts, which ran without bushings directly in the “hemi” cylinder head. Cams operated the eight valves directly with shim-and-bucket adjustment. Suzuki even chose the exact same valve sizes and camshaft timing as the Kawasaki Z1/KZ.
A straight-cut gear on the crankshaft drove the clutch, which was removable without splitting the engine cases, to the 5-speed gearbox. At the rear of the frame, the swingarm pivoted on needle roller bearings (not the rubber bushings used in most bikes) making for more rigid alignment. The 1977 launch bike featured spoke wheels and a single brake disc front and rear — though within two years the updated GS750EC featured cast wheels and dual discs up front.
While being relatively docile and tractable on city streets, the GS really came alive once the tachometer hit 6,500rpm. From there, power came in much more strongly to its peak at 8,500rpm and all the way to the 9,500rpm redline, where it was still making almost 58 horsepower. At the strip, this translated into a 12.75-second standing quarter at 104mph.
And while straight-line performance was a given in the new superbike era, capable handling was not, as Cycle Guide noted of the KZ1000 in its comparo with the GS750. The former would “wallow when we hit any kind of bump when leaned over.” In contrast, their testers praised the Suzuki’s fine handling and relative lack of steering vagueness, something they put down to a rigid frame, combined with the needle-roller-bearing swingarm, relaxed steering geometry and a long 59-inch wheelbase. Steering was also noticeably lighter than the big Kawi with less weight over the front wheel.
Cycle Guide’s criticism of the new GS was limited to a slightly-too-firm seat, over-sensitive rear brake, and some slight oil weeping from the front fork. They summed up: “The GS750 is without doubt the best-handling big-bore Japanese streetbike around … it goes faster and handles better than other 750 multis without losing ground in other areas.” Wrote Cycle in January 1977, “It is without question the best motorcycle in the 750 class,” then nominated the GS750 one of its best five bikes of that year.
Honda and Kawasaki soon released DOHC 750-fours of their own; but the GS750 had sparked a technology race, which led to 4-valve cylinder heads, liquid cooling and aerodynamic bodywork, and eventually gave us today’s race-replica sport bikes. MC
Contenders
1975-1979 Honda SOHC 750F/750F2
- 54hp @ 8,250rpm/ 114mph, 60hp @ 8,500rpm /111mph
- 736cc (61mm x 63mm) air-cooled SOHC eight-valve inline 4-cylinder
- 5-speed, chain final drive
- 525/542lb curb (half tank)
- Price then/now: $2,148 (1977)/$2,000-$7,000
Honda’s 750 Four K0 of 1969 defined the air-cooled inline four motorcycle for a decade. But by 1975, the DOHC Kawasaki Z1 featured newer technology. Honda’s response was the updated 750F Super Sports, identified by a new 4-into-1 exhaust. At the rear wheel, a disc replaced the mediocre drum. Reduced trail and a longer swingarm preserved straight-line stability, while a stiffer frame and suspension changes improved handling. The engine was claimed to be unchanged, though Cycle magazine recorded 58 horsepower at the back wheel (49 for the 750K), which gave a standing quarter in the high 12s. On the road, the drivetrain and handling improvements together with longer suspension travel made for a comfortable ride and precise steering. The downside: a weight increase of 12 pounds.
New for 1977, the 750 F2 (shown) featured Honda’s problematic ComStar wheels, with triple disc brakes and a new quieter muffler. The engine featured larger valves and more radical cams giving 60 rear wheel horsepower, but at higher rpm.
While they were attempting to verify Honda’s claim of sub-13-second standing quarters. Cycle Guide’s test bike dropped a valve, destroying a piston and the cylinder head. The cause, they suspected, was insufficient heat treatment of the valve.
“We didn’t abuse the CB750,” explained Cycle Guide’s review, “but we pushed it to its limits — and then just past.”
That aside, testers considered the F2 to be the best Honda 750 so far, the result of continual refinement and improvement. Honda had created a comfortable and fine handling motorcycle with performance that just about kept pace with the GS750.
1979 Kawasaki KZ750
- 55hp @ 9,500rpm (rear wheel)/120mph
- 738ccc (66mm x 54mm) air-cooled, DOHC, eight-valve inline 4-cylinder
- 5-speed transmission
- Dual disc brake front, disc rear
- 491lb curb weight (half tank)
- Price then/now: $2,749 (1979)/$1,500-$3,000
While it was the Suzuki GS750 that pioneered double overhead cams in the 750cc class, in 1979, Kawasaki struck back with the KZ750. Essentially a stretched KZ650, the Kawi 750’s main advantage was its light weight. At 491 pounds at the curb, it was 51 pounds lighter than the CB750F2 and 20 pounds under Suzuki’s GS750. Though recording just 55 rear-wheel horsepower on the dyno, the KZ stayed with the CB and GS on the strip, recording 12.5 seconds at 107mph for the standing quarter. And while conceding outright performance to both the Suzuki and the then new 16-valve Honda CB750F, the KZ750’s light weight also gave it the edge on the track and in throttle roll-ons — as long as it had 4,500rpm on board.
The secret of the KZ’s sparkling performance lay in its cylinder head, which was designed to breathe freely through ports smoothed with epoxy. This allowed the use of huge 34mm Keihin CV carbs. Below was a plain bearing crankshaft with five mains, Hy-Vo chain drive to the two camshafts and a central gear primary driving the transmission. The engine went into the same KZ650 frame, but with 20mm lower top rails to reduce seat height. Final drive to the cast alloy wheels was by chain, and triple disc brakes provided stopping power.
Testers appreciated the lighter weight of the Kawasaki, noting that motorcycles in general were getting too fat. The Kawasaki proved to be lithe and nimble with good handling, adequate braking and decent comfort. While having no standout positive attributes, “It’s a motorcycle totally without serious fault,” said Cycle World.
I had been riding a '72 CB750 (among other bikes) I had bought new and got to know it well when in '80, a fellow worker sold me his '77 GS which he was replacing with a CB750F. This gave me the chance to compare the two bikes side-by side. The GS with it's four valves and dual cams had way more punch. I found it to be a better handler, braker, and just about everything else better performance wise than the CB750 on which by that time I had accumulated over 20K miles ... mostly on long cross-countries. But that's where I found the Honda to excel ... comfort ... and probably overall looks too. But then, that just personal taste. I never took the chance to ride the Z1 and was very tempted to slap down the extra $500 over the CB but didn't. I am a bit surprised over the comment about the Z1 handling though. If my memory serves me right, the magazines at the time tended to give the Z1 pretty good marks in that area for the size of bike. The CB750 wasn't a great handler but she was solid which made casual touring a pleasure. If only she had the power of the GS ...
I was already a 16 year-old Suzuki nut in 1977 when the GS-750 came out in 1977... though my heart still belonged to two-strokes. I was still riding my GT-380 in my senior year of high school in 1978 and I needed an excuse to get a bigger bike for my "Graduation gift to myself". I actually wrestled between the GT-750 (in black in 1977 - its last year) and the brand new GS-750, but the salesman - who was also a friend - talked me into the GS, saying that it was an "all new design" vs the GT which was an already 6 year old design. Plus the performance numbers could not be argued with. OK - I gave in and got the 2nd year 1978 GS-750. Since I was already concerned about the GS's 510 lbs (I only weighed about 125), I opted for the "Standard" GS with wire wheels and the single front disc brake... as this saved 15 lbs compared to the "ES" with the dual front discs, the mag wheels and the stepped seat. Mine was a very pretty deep blue with light blue and gold striping. I had that bike for 10 years until 1988. In all that time, though the GS was a great bike, it actually never quite lived up to my expectations. Coming from the GT-380, I imagined that this bike would have "twice the power", and in some ways it sort of did (67 HP vs 38 HP) but it weighed about 100 lbs more than my GT380, and the GS had a pretty soft mid-range (vs the GT-380's which actually had nice fat mid-range for its size) so it never felt how I imagined. Still a very nice bike that did everything well. I had a friend that owned a 1973 Z1 and we swapped bikes on a few rides, and suddenly I understood how much better the GS handled and how the engine felt so much smoother and more refined that the big Kawi... I was always glad to get my GS back after swapping. Now 43 years later, and even more bikes later (no kidding I am a collector and currently own 37 Suzuki's(!) - not surprisingly mostly 2-strokes), the GS-750 would be the last time I bought a brand new bike. In 1988, I sold the GS-750 to make room for my (used) 1983 GS-1100E in bright Red. A gorgeous bike to my eyes with the blacked out engine! And now I finally had the engine and grunt that I imagined my GS-750 having. All at basically the same weight as the GS-750 and with a top end kick of some 110 HP to boot! I kept this bike for 3 years until 1991 when I sold it to buy the true love of my (2-wheel) life... a bike I still have today - my RG-500... So awesome was this bike, that I became an RG fanatic, and bought and imported the other *7* RGs that I own today (8 total) - all of them different (RG-50, RG-125, RG-150, RG-200, RG-250, RGV-250 (VJ-21) and RGV-250 (VJ-22)... did I mention that my heart belonged to two-strokes?... Cheers!
I owned one of the first GS 750 motorcycles delivered while I was living in France. Standard equipment included 2 disk brakes in front. The Suzie was by far the fastest Japanese superbike on the road due its superior handling and brakes. It outpaced even the ever so slightly more powerful Kawasaki Z1, which was heavier, had perfectible handling and did not brake as well, though you could add a second disk to improve that. The GS was the best of the best UJMs. Acceleration was very strong and cruising at 180 km/h was natural to the beast. Being a speed-crazed young man I did push it to the limit way too many times and it never let me down or showed any sign of brake fading or other gotchas. The sound of the engine was so muted that the wind was all you could hear when riding at high speed on the highway. I never had a single problem with it, which didn't surprise me because Suzuki had long been building very reliable motorcycles. Looking back, the engine could have had a little bit of personality and a flatter torque curve, but that was the lot of all four bangers. Competing two-strokes were two triples: the Suzuki GT 750, a heavier, less powerful bike with a wonderful engine sound but not-so sporty handling, and of course the Kawasaki 750 H2, whose poor handling made it known as a widow maker, just like its parent the 500 H1.