Yamaha XJ650 Turbo, superfuturistic and powerful

0
93

Technological revolution with superbike power and the appearance of a motorcycle of the future, this is the incredible Yamaha XJ650 Turbo, a motorcycle that does not leave you indifferent when you see it.

Although there is no documentation about it, surely the tuning fork brand managed to find out -albeit very late- that Honda was developing a turbocharged motorcycle. That is why they decided to create their first turbo in a hurry, at whatever price, in order to arrive -at least- at the same time as the competition at the 1981 Tokyo show, to go on sale in 1982.

And they succeeded, but Iwata’s bike, although it was aesthetically very attractive, lacked a little more development so that the engine and the chassis were really balanced. But despite all this, the second most popular turbo bike is, without a doubt, this Yamaha XJ650 Turbo -whose official name is XJ650T-.

It was launched at the same time as the Honda CX 500 Turbo in 1982

It was a very futuristic and attractive motorcycle, although it was simpler than the Honda, less technically elaborate, but despite this it worked well thanks to its simplicity. In their development to save costs, they started from the drive unit of the reliable and proven XJ650, a simple four-cylinder in-line transverse -4T, air, 8V, DOHC- with cardan shaft final drive.

Photo of the Yamaha XJ 650 Turbo
The aesthetics of its fairing and tail were certainly very attractive.

If the Honda CX500 Turbo was fueled by electronic injection, this blown XJ was powered by a classic and simple battery of four 30mm Mikuni CV carburetors, working at overpressure thanks to a small Mitsubishi turbocharger just 39mm in diameter – the IHI of the CX Turbo had 50 mm-.

A turbocharged motorcycle fueled by carburettors… It was the only turbocharged motorcycle that did not have electronic injection, which gives an idea of ​​the aforementioned: it is a very simple motorcycle technologically speaking, an indicator that work was done in a hurry to launch a model turbo at the same time as Honda…

The Yamaha XJ650 Turbo was the first and only serial turbo motorcycle of the Iwata firm, as is the case with the rest of the motorcycles of its lineage

Continuing with the theme, to avoid the typical problems of lag -delay in the throttle response- of turbo engines, the carburettors were fed with air coming from an airbox divided into two parts.

Photo of the Yamaha XJ 650 Turbo
Its four-cylinder engine offered 85 hp, a good figure for its time.

When the turbo pressure was not enough -at low revs- the carburettors were fed directly from the air, it was an aspirated engine, while when the turbo pressure was already correct, thanks to a simple mechanical reed valve, the conventional air passage and was fed by the air blown from the turbo.

This was also applied to the fuel line, to prevent turbo air pressure from reaching the fuel tank, using a fuel pump and various bypasses and valves, all mechanical. The simplicity remained. The placement of the turbo was also strategic, as close as possible to the exhaust and intake manifolds.

It was a sport tourism in which comfort prevailed over extreme handling

It was installed just below the transmission output shaft, on the left side, where the cardan joint went towards the rear wheel, because there was “a gap” and because it was halfway there. This was also possible because the turbine was much smaller than normal, despite the fact that it delivered the same blowing capacity and rotated without problem up to 200,000 rpm.

The exhaust was a four into one, with all four manifolds converging on the turbo; it discharged the exhaust gases only in the silencer on the left side, despite the fact that this turbo had two exhausts…

Photo of the Yamaha XJ 650 Turbo
Its ergonomics, fairing, seat and driving position were focused on providing ride comfort.

And here lies another curiosity. It had two exhaust silencers, but the gases were only expelled through the one on the left, which was connected to the turbo outlet. And the right exhaust? Well, it only served to discharge the turbo overpressure valve…

Its pointed full fairing was designed to exert downforce on the front axle

Despite all this deployment, the engine suffered from lag, that is, the turbo took time to come into action when the throttle was opened. Yes, the Mitsubishi turbo was quicker than the Honda Turbo’s IHI, but it still took a second to respond—the Honda took a couple.

Lag aside, thanks to all this, the power offered was 85 hp, a very good figure that forced Honda to launch the evolution of its 500 turbo a year later, launching the CX 650 Turbo, with 100 hp.

Photo of the Yamaha XJ 650 Turbo
The automotive court instrumentation included a check of some components of the motorcycle.

Returning to this XJ Turbo, if simplicity was maintained in the engine, it was also maintained in the cycle part, with a classic steel double cradle chassis with a 36 mm fork and air-assisted bars, plus a pair of rear shock absorbers in classic configuration – the rest of the turbo bikes had a single shock absorber with linkages.

The rims and brakes are almost practically the same as those mounted on the humble Yamaha XS400

The precious alloy wheels were too narrow, with a rear tire size of only 110/80 x 18” -the front was 19”-, with a pressing lack of rubber to manage 90 hp. You just have to think that the humble Yamaha XS 400 (launched in 1983) with 45 hp -half the power- was equipped with the same wheels -they shared design- and suspension measurements of the Turbo, with an identical rear tire, and the 400 already I was right in this regard…

And in terms of brakes, the Turbo wasn’t too bad either, since it had two small 266 mm front brake discs with single-piston calipers and… a rear drum! Only one more disc than the XS 400 and with the same diameter… They worked a little more on its aesthetics, since its large and beaked full fairing protected the rider a lot, as well as being attractive.

But there was something more, since, for the first time, this fairing influenced the dynamics of the bike: its design was intended to load more weight on the front axle as speed increased. Hence, the front was so prominent and beaked, and that a small spoiler was available on the bottom. In fact, this elaborate fairing was later used to equip two more models launched in 1983: the XJ550S and the XJ750.

Photo of the Yamaha XJ 650 Turbo
From any angle this Turbo was beautiful.

It was the only turbo that did not have an electronic injection to feed its engine

In ergonomics, its seat was generously foamed, designed so that the pilot could do many kilometers comfortably, and the driving position kept the pilot quite upright. It was a sport tourer oriented to swallow miles, with a certain joy.

And as for its instrumentation, it was automotive style, without spheres, very futuristic and full of information. It included two dials for speedometer and tachometer, which shared the same space, and in the middle of these was a small LCD screen for fuel level, turbo boost level and the usual collection of whistles.

But there was something more as Yamaha declared that it was the first motorcycle in the world to include an electronic component diagnosis system. Thus, the LCD screen showed a check of the status of the battery, brake fluid, engine oil, lights and side stand.

It was launched on the market with a price that doubled that of the standard XJ650, really expensive… For the year 83 -last year of production-, some improvements were introduced in the cycle and engine part.

Photo of the Yamaha XJ 650 Turbo
The tail, non-existent, was occupied almost entirely by the rear pilot.

Thus, the diameter of the bars was increased, new shock absorbers were mounted, the blowing power and the size of the fuel tank were increased, the front brake calipers were strengthened, the brake discs received more ventilation slots, as well as new fenders and rear turn signals and small tweaks to the fairing.

Along with the Honda CX 500 Turbo, it was the most popular turbo bike, if not the best-selling

But Yamaha had to fight against the wonderful turbo from Honda, which outperformed it in power and stability. To deal with this, Yamaha distributed a free upgrade kit! among your customers. With this kit -turbo opening spring and part of the final silencer- the blowing pressure was increased from 7 to 12 psi. Almost 40% more…

The problem was that Yamaha sold out of the kits… Users of version 83 were lucky to receive all these improvements… at a better price. The total number of motorcycles manufactured -years 82/83- amounted to 8,000 in total, the same units that the Kawasaki GPZ 750 Turbo sold.

The XJ650 Turbo had a good engine that never suffered from serious faults or carburation, had a bold and beautiful futuristic aesthetic, and was only marred by weak brakes and laggy response.

In spite of this, today, 40 years after its commercialization -which is exactly in 2022-, it is still a collector’s motorcycle, very futuristic and that leaves no one indifferent when they see it pass, if it is that can you see any…

DATA SHEET

Engine: 4 cyl. inline, air, 8V, DOHC
Displacement: 653cc
Maximum power: 85 hp at 9,000 rpm
Max Torque: 7.5kgm at 7,000rpm
Feeding: 30mm Mikuni carburetors with Mitsubishi turbo
Change: 5 speeds
Clutch: Multi-disc in oil bath
Transmission: by gimbal
Chassis: Full steel double cradle
Front suspension: 36/140mm air-assist fork
rear suspension: double shock absorber
Front brake: 2 x 266mm discs with single piston calipers
Back brake: 220mm drum
Tires: 3.25 x 19” and 120/90 x 18”
Distance between axis: 1,445mm
Seat height: 780mm
Gasoline deposit: 19.5L
dry weight: 245kg

Previous articleUS GP, Free Practice 1: Sainz leads, Alonso 6th and Palou debuts
Next articleLoneliness and not being happy accelerate aging more than smoking

LEAVE A REPLY

Please enter your comment!
Please enter your name here