What Yamaha succeeded so wonderfully with the XS 650 line, that also got Suzuki thinking. There was still a demand for and a market for 'classic' parallel twins after the English example. Only the general opinion was that to be happy with that… at least you don't have to have a British twin. The Yamaha XS 650 line became legendary and iconic. But if you proudly report that you own a Suzuki GR(D) 650 'Tempter'. Then misunderstanding is your part. Oh, yes: Suzuki's own British twin was just launched too late to be a success.
The Suzuki GRD 650 was an advanced design derived from the GS450
The Suzuki GR 650 was powered by a four-stroke air-cooled DOHC parallel twin with two valves per cylinder. This engine had a 180° crankshaft with a gear-driven counterbalancer and a wet sump. The carburettors were two Mikuni CV BS36SS. To create vortex in the air-fuel mixture, Suzuki added a sub-intake port that connects the carburetor venturi to the intake port just above the valve head. Suzuki claimed that this allowed the GR 650 to run with a leaner mixture than usual, which improved fuel economy. Two jets of oil gave the pistons a significant cooling bonus at higher engine speeds.
A smart flywheel
The Suzuki cleverly featured a two-stage flywheel that used a centrifugal clutch to disengage a secondary flywheel above 3.000 rpm, effectively reducing the mass of the flywheel. This was intended to dampen vibrations and provide an easier start at low revs and improve responsiveness at higher revs.
The Suzuki GR 650 Tempter is considered a robust two-wheeler. The engine's performance curve at relatively low speeds allows for lazy riding. There is no need to shift gears to make the engine run smoothly. But switching does the five-speed exemplary. In a recent test ride, the comfort-designed chassis and the good handling of the machine in tight corners with a relatively high degree of lean clearance and the stability of the fork were noted as pleasant. However, unlike the British examples, the Suzuki was more of a bike for leisurely touring and cruising. The curb weight of the twin also played a part in this. The caveat for tourist deployment was that the tank capacity was not very large.
The Suzuki GR 650 was sold in two trim levels
The GR 650D and the GR 650X. The GR 650X came with traditional wire wheels, a monochromatic paint scheme and non-adjustable front forks. The Suzuki GR 650D got a two-tone paint scheme, cast alloy wire wheels, an extra running light under the headlight and adjustable auxiliary air suspension at the front.
The weak points
Almost 50% of all GR models, especially those of the early years, pitting occurs on the third gear pair, an ailment that we already knew from the T500. The alternator stator often tends to short circuit. The regulator rectifier unit also often breaks down.
The diaphragm actuated fuel cock: Even with minor leaks (visible when the fuel hose is disconnected), fuel may run through the inlet channels into the combustion chambers and the connecting rods may bend easily when the starter is operated if the piston rings are properly sealed (fuel impact) after a long period of time from standstill. And we also know that phenomenon from the Suzuki XV800.
With a volume of 12 liters, the tank is therefore too small for longer distances.
You don't see these Suzukis very often. And then you suddenly see two for sale. The only problem is that the shed is already sufficient. If you find one, it won't cost you much money. So go for a topper. And then think of max. 1.750 euros. So who says classic driving has become unaffordable?
They are the 'known' ailments. had 15 Japanese and they all had a stator encased in motor oil. That means: hot/cold/chemical exposure and in addition, delay of refreshment is sometimes disastrous, metallic splinters are disastrous for the insulation and your short circuit is there. The voltage regulators are built to 'flare off' excess current through heat transfer from outside air. Too much thermal insulation, poor heat transfer and the recipe for an overheated regulator/boiled battery! Modern petrol is disastrous for rubbers/plastics. See there: the entire fuel routing from tank to piston bottom, parts come into contact: valve seals, float needles, floats, hoses, diaphragms, diaphragm pumps, valves…. All withstand the time but shorter than intended and just when you are in the polder past Lelystad. If you keep this in mind and act on it, you have a reliable engine for years to come.
Hi Maarten, I don't know a "stator in motor oil bivouacking" on a Japanese motorcycle. Mind you, I do not claim that such a thing does not exist, but I only know of situations where a stator, and therefore also the rotor, is separated from oil from the block by a seal ring. Of various English classic twins, the stator of which is placed around the left crank pin, and in the presumed present oil of the primary case where often the venting of the crankcase also contributes. That electrical system from the not highly regarded manufacturer Lucas also contains the “flare system” you described in the form of a Zener diode and an aluminum radiator. A pitifully primitive system whereby the dynamo always ran at full power (and therefore also took power for the rear wheel) by converting the balance into heat even when the battery is charged. The advantage was that it was cheap to realize, a decisive argument for British brands at the time. And yes, it worked, more or less. One of the elements that made the Japanese motorcycle dominate the world market is the electrical system, which was of a higher quality from the start, and was soon designed more intelligently. I am not aware of any construction of a 'heat sink' on the Japanese bikes I have ridden and maintained. The only electrical defect I've had with a Japanese bike was a short circuit in the wiring at the headset, a combination of mechanical stress and outdated insulation. But I may have been lucky and therefore drive a now 24 year old Honda NTV650 every week without any worries.
I have worked in a motorcycle shop in the Westland for 30 years and have also seen the motorcycle pass by, but left no impression on me. 🙂
It strikes me that possible shortcomings are mentioned that I have never had to experience with any Japanese bicycle. Admittedly, I haven't done enough miles with the Yamaha SRX to experience the familiar fifth gear shortcoming. But a short-circuited stator and a helluva rectifier; that's new to me. The appearance of this for me unknown Soes has gone too much in the direction of 'Japanese chopper', which in my opinion is a style icon of 80s bad taste. That seems to me to be an explanation as to why this product did not really catch on, and certainly not as a replacement for a classic English Twin, which in the end had to rely mainly on the appearance.
But such a flywheel? You always learn something new!