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Bike Review - Posted 21st October 2013
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Suzuki GR650

In the mid-1980s, Suzuki built their interpretation of the traditional British bike: an air-cooled 650 twin. As Paul Shiel has discovered, with a few tweaks, it's still really rather good...

The GR was built from 1983 to 1989 and looked both forward and back in terms of motorcycling technology. Its engine layout conformed to that of the traditional British twin - two cylinders, arranged side by side, firing at 180 degrees, air-cooled - but was updated with chain-driven double overhead cams, wet sump and an inventive (if not entirely successful) dual flywheel system.

Simple, quick, nimble, economical... Original Suzuki GR650 Advertisement

That motor was housed inside Suzuki's 'Full Floater' monoshock chassis with a single disc front brake and an entirely traditional rear drum brake. Cycle World tested the American version (aka the Tempter) in 1983 and said: 'There is a feel of suppleness not found on most motorcycles as the GR650 glides over bumps and dips. Sit on the Suzuki and the bike settles more than expected. It does this whatever the preload setting in back and whatever air pressure is used in front. Mostly it's the rear suspension that gives the GR650 its floating-on-a-cloud feel.

'Riding the Suzuki 650 is in most other ways satisfying. It doesn't have many annoying features, those little quirks that make some bikes frustrating to ride. It starts easily with the push of a button and handles predictably on all kinds of surfaces. Particularly at low speeds the Suzuki is an easy handling bike. It invites riding on bad roads where a rider needs to steer at the last minute around obstacles or holes.


'The rest of the bike is happiest on back roads, too. The single front disc brake and rear drum brakes are better than Suzuki's fancier triple-disc systems with anti-dive. Because of difficulty bleeding the anti-dive systems on more expensive Suzukis, they lose brake feel; the 650 doesn't.

'Engine characteristics, and more important the gearing, also fit the low-speed nature of the 650. More than most any other mid-size Japanese twin, the GR650 is tuned to provide lots of low and mid-range power. The swirl-inducting air jets, the carefully tapered and small intake ports and cam timing all make for an excellent, broad powerband. What it doesn't make is peak power.

There's all sorts going on in there... Suzuki GR650 Engine
'Classic' Suzukis on

'Up to 60mph the 650 Suzuki is a joy to ride. At low speeds the engine is smooth and there are no gaps in the powerband. It pulls from idle, the two-stage flywheel doing its job without intruding. Below 3000rpm it pulls like a tractor and is amazingly resistant to stalling when the clutch is let out too quickly. Above that the engine is somewhat more responsive, but there is no real transition. You don't feel the flywheel disengage or engage. The clutch is magnificent. Start the Suzuki cold, put it in gear and you don't hear a sound or feel a tug. It releases fully. It never gets grabby hot or cold. This can't be said for the clutches on some of Suzuki's other mid-size bikes. Add shifting that's light and responsive and it makes exercising the 650's engine a pleasure.

'Only the growing level of vibration above 60mph intrudes on the fun. Even with the counterbalancer shaft, the engine feels busy around 5000rpm, and with an engine speed of 4650rpm at 60mph that vibration period comes at common highway speeds. Above 70mph things settle down a little, but the real sweet spot is just at or below 60 mph. Up to that speed it maintains that delightful Big Twin feel, chugging the bike forward with authority.'

I quite like that seat... Paul's Suzuki GR650 as bought

I picked up my own green 1988 GR650 here in Australia about a year ago, with 18,000 kilometres on the clock. It's an ex-Australian Military Police machine mainly used for escort duties. The GR was an underrated bike of its time. It's light with good handling, and bags of low-end torque guaranteed to put a smile on yer dial. But I wanted to do a few subtle improvements to it.

I've had the seat reupholstered using the original base to a more comfortable shape, replaced the handlebars with something which would be more at home on an English bike from half a century ago, changed the fork oil to 20W and added an inch spacer for the springs. These modifications improved comfort and control for my 'ample' (six foot tall) frame no end.

Exhausts look the part... Paul's Suzuki GR650 as it is now

Then onto the exhaust. The restrictive double wall headers were replaced with a stainless steel mandrel formed by a workshop that makes bull bars: $100 well spent, I think. The reproduction Peashooter mufflers of an annular design came from the USA.

These changes necessitated carb adjustment: pilot 45, needle up one notch, mains 145, and this resulted in a healthy increase in torque and power. To take advantage of this I raised the engine sprocket by one tooth (to 16t) as the standard gearing was too low.

Now the GR has sufficient torque to take off on its own, almost without throttle, by just releasing the clutch. Overtaking is rapid without needing to change gear, and acceleration is quite brisk up to the ton with little or no vibration. And it still returns 60mpg!

Colour scheme lets the engine dominate...

All round, the GR is a big improvement on the XS650 I used to run. If things had been different, perhaps this is a bike which Triumph coulda, shudda built in the 1970s

Photos Paul Shield


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