Suzuki GS 450E

Which Bike review 1980

The final conclusion in the test last year of the Suzuki GS425EN ended with the suggestion that the bike should really have been a four-fifty. In other words, although it was a presentable bike, it just wasn't gutsy enough to make any lasting impression. As a work horse, of course, the four-twenty-five had plenty going for it, as no end of messenger riders will agree. But for fun biking, it just couldn't cut the mustard.

Suzuki must have appreciated the fact that the GS400 needed more than a slight overbore to help it compete in the nasty, below-the-belt world of middle capacity roadsters. For not long after the introduction of the 425 came the news of an even bigger twin, a 450 no less. And evidence that Suzuki have been aware that a longer-term panacea than bigger pistons was necessary to revive their mid-range model is that the GS450 is a completely new machine. The only similarities between the GS425 and the GS450 are in the general layout of the engine and frame, which are now roughly common to the smaller GSX 250 twin. So the 450 is a double overhead camshaft parallel twin with a 180-degree crankshaft and a gear-driven counter-balancer.

The only common group of components are in the six speed gearbox. To get the extra capacity, Suzuki could have just opened the bore size even further. But they didn't because other factors had to be considered.
The most important of these was noise,both mechanical and exhaust. Suzuki have long used ball and roller bearing crankshafts for their four-strokes but they are relatively rattly. So with the new models they switched to quieter-running plain bearings and at the same time designed the crankshaft with a shorter 56.6mm stroke which meant that 71mm bores were required. This makes the 450 much more oversquare than the 425.

Interestingly, primary drive on the 450 is by straight-cut gears, while those driving the heavier stubby balance shaft in the front of the cases are helically cut, which is the opposite of that used on the GSX250. Perhaps the noise production of the 450 primary drive is more critical. Either way, the reduced mechanical noise of the 450's engine allows the exhaust to be louder and less restrictive. And despite not using the Twin Swirl Combustion Chambers with four valves seen on the 250, 750 and 1100, the 450 and its conventional two-valves per cylinder and bucket followers punches out a useful 43bhp at 9,000rpm, three more horses than the 425, with the funky off-beat exhaust note more associated with Honda's racing twins.

The extra top-end power of the 450 was expected but the way in which the bike pulls from lower down the range came as a complete surprise. Throttle response from the twin constant-vacuum 34mm-choke Mikuni carbs is remarkably good, so good in fact that riding solo you can just rely on the engine's pulling power without the need to keep jumping up and down through the gearbox.

Should you be of a mind though, the GS450 makes a great scratcher when you pile on the revs. The bike is very smooth, surprisingly somewhat smoother than its 250 brother at the top end though the rear view mirrors seem to find more than their share of buzzing. You'll need those mirrors too. The GS450 is a very nimble and light machine for its capacity, tipping the scales at 3861b dry, some 301b more than the 250 and 121b more than the old 425. It picks up speed very smartly and can cruise at anything up to an indicated 90mph and with no trouble at all will pull l00mph in top gear.

That puts the 450 alongside and ahead of many of the 500cc machines with a quarter mile time of about 14.5 secs. But although the performance is snappy the fuel consumption is still very good. Even riding hard the bike returned 55mpg.

In keeping with the 450's performance is a riding position ideally suited to high speed riding. The handlebar is flatter than on the 250 twin and the footrests mounted farther back on chromed plates, the gear lever being connected to the gearbox through a linkage. Wind pressure is effectively balanced at about 70mph by body weight and the rider has a good perch to counter hard acceleration. But this is at the expense of wrist comfort riding in dense traffic. The positioning of the handlebar also makes it difficult to quickly use the new-style thumb switch on the left console. On this there is just a single lever that moves in four directions for both the turn signals and headlight dipping.

That acceleration is good enough to jerk up the front wheel in bottom gear when the last movement of the clutch is taken up, more so when you're packing a passenger, for which the 450 has ample clout and room on the dual seat. The handling of the 450 was slightly squirelly. The frame differs marginally in detail fromt he 425, mainly in the positioning of the frame tubes around the swing arm pivot. Steering head bearings are tapered rollers and the swing arm rides on needle rollers. The bike felt very light and nimble at speed and the tyres, Bridgestone Mag-Mopuses give good roadholding. We thought the suspension was slightly mismatched with a softly damped and sprung front fork that would dive badly under hard braking. The rear end was by comparison fairly hard. The bike is so easy to handle that any shortcomings in the handling can be easily overcome.

The brakes were very good too. As mentioned in last month's test of the GSX250, the front disc brake uses new style disc pads and a one piece rotor that give great feel under breaking which is also helped by the dog-leg handlebar levers. The reasons why the brake is so good has been difficult to establish. Some may be the pad material, some may be the disc, which was not stainless steel as was used on previous Suzukis, because it rusted after a night in the rain. The rear brake is a drum unit with good lever feel and power.

The GS450 is a surprising newcomer to the class, whether you call it a 400 or a 500. It starts easily (there's no kickstarter) and the lights are reasonably okay. Above all the bike feels exciting; the nearest model we could compare it to was the RD400 Yamaha. And with good economy, you couldn't provide the GS450 with a better testimony.