Yamaha XJ 600S Diversion

The XJ600S is known as the Diversion in most parts of the world but as the Seca II in the North American and Australian markets. The bike has a small top fairing although a lower fairing is available as an accessory. The XJ600S is a descendant of the XJ600 models manufactured between 1984 and 1991. It is fitted with a 598cc, air-cooled 8-valve inline-four engine producing 61 hp (45 kW) and 55 Nm (41 lb-ft).  The engine from the original XJ600 model was tuned towards improved low- and midrange power, sacrificing some peak power.

600cc Diversion models were manufactured from 1992 to 2004. The US Seca II was manufactured from 1992 to 1998. As the Diversion/Seca II design is based on an earlier, well-matured model, changes made to the bike during these years were rather subtle, mostly concerning improvements in fairing: a second front-brake disc and small oil cooler appeared on the 1998 model along with improvements to the carburettors.

The Diversion favours an upright riding position more than most 600cc sport bikes, making it usable for commuting. It remained in production for quite a long time, probably due to its low price, modest fuel consumption, longevity and reliability.

Source  Wikipedia

Review 1992

"SO WHY THE 'S it called the Diversion then?"

That's the question the editor of Performance Bikes dared me to ask at the press presentation. There was a fiver on leaving in the expletive but I bottled out - not wishing to offend our hosts in the Swiss Alpine resort of Gstaad - but I'd still like to know why it's named after some intangible marketing policy.

BIKE did all the 'alternative route' jokes last month so I'd got a rare old collection of Julie Andrews gags lined up for this - until I discovered The Sound of Music was all about Austria. Still, the Diversion philosophy IS all about an alternative route and the Alps are the Alps - all singing nuns and cow shit.

Alternative route as in different from the road down which Kawasaki has gone to attract first time riders and RC starters. The XJ600S Diversion is certainly no Zephyr, as Yamaha is at pains to point out: "This is no retro bike aimed at re-creating the 'good old days'. This is a machine for the '90s." And built to a price, I might add.

It looks the part. Four cylinders, worth 598cc between them, slope forward at an angle of 35 degrees and the inlet manifolds and carbs point straight up under the humpty-back tank. This creates a space behind the block big enough to get a bus through - well almost, and one of the Yamaha staff did try it, honest.

The silver lacquered engine sits in a steel double cradle frame which is painted to match the bodywork. Close scrutiny of those akward little places revealed a worrying lack of paint, raising questions about the bike's ability to cope with winter.

Diversions come in two colours: red and dark green, both of them subtle pearl finishes that glow lustrously in the sun. Graphics are so restrained as to be virtually nonexistent. It says Yamaha on the tank and a copy of a Ford logo on the fairing bears that word, Diversion.

It's the fairing that is the Diversion's big plus. The bike is supplied with two screens - a shorty sporty and a taller tourer — and a pair of aerodynamic 'ears' that bolt on the side of the fairing in minutes. The options produce remarkably different wind-cheating characteristics and it's great to be able to modify your fairing according to the weather/journey.

A combined side-panel/seat tail moulding sweeps up from the base of the tank to the pillion grab handles and stowage space. This emphasises the modern look.

What's it like to ride then? Well, half a dozen or so British journalists were given the opportunity to test the bikes for one sunny day on twisty Swiss mountain roads. If you want to know what it's like through tight bends and over quick sprints I can tell you it's fine - a lot of fun. But if you want an appraisal of its performance in the wet, on long straight roads and at night you'll have to wait for our full UK test.

The seating position is virtually upright with slightly raised bars and rearset footpegs. After 163 miles I noticed a slight ache in my ankles, but this was probably more due to the frantic working of the gearbox and restraining myself from the over-keen rear brake.

A low, manageable seat height and centre of gravity will instil confidence in Yamaha's target mar recently qualified riders and returning to the fold. Monocross rear end with its long swingarm and preloadable shock behaves itself.  With 38mm diameter front forks gives a well-balanced ride with no fast bend weaves or wobbles.

A single front disc brake hauls the slimline Diversion and its porky pilot to rest with no trouble — thanks to its 320mm diameter and twin pot caliper. It will pull up rapidly when the novice rider has to, but won't spit them off if they grab a too enthusiastic handful. The rear brake however has the 130/70-18 Yokohama leaving its calling card on the road at the slightest dab.

Power output is not going to have CBR and ZZ-R600 owners rushing to dealers for a trade-in. At 60bhp the Diversion is in a different class, and that's just where Yamaha wants it to be. If you've been reading BIKE for years you're probably starting to lose interest and thinking of checking out the GSX1100G test. But if you're a recent convert Yamaha hopes you might be getting excited.

There's only one word for power delivery. ..smooth, with a long ooo. Apart form a mild tingle through the footpegs at 4000rpm, which disappears 500rpm later, the eight valve engine pours out like Swiss yoghurt, ooo, mmm. Engine mounts are rubber at the front left-hand and rear right-hand fixing points and rigid at the front right and rear left. A non-roller cam chain (sic) and rubber dampers on the final drive sprocket help to keep vibrations to a minimum.

Mirrors remain clear and sharp at all times apart from that 4-4500rpm buzz zone.

Exhaust down pipes are knitted across the front of the engine so cylinders one and four feed the left silencer and two and three go to the right. This arrangement makes best use of the exhaust pulsations from a 1-4-2-3 firing order and creates a fine sound and a deep hum on the overrun. Access to the oil filter is not impaired but the fussy engine plate arrangement will suffer at the hands of a short front mudguard in the winter. The clutch operating mechanism on the top of the right-hand casing looks suspiciously vulnerable to the elements too.

Being a mad-as-a-fish ZXR rider I abused the Diversion horribly. Mile after mile of third and fourth gear bends with the rev counter needle wavering twixt eight and 9000rpm - and the masochistic little devil loved it. Vigorous use of the 'box reveals a rather pernickety gear change but familiarity with its traits and a few thousand miles will no doubt aid selection. Neutral was occasionally hard to find and there's a big leap in ratio between first and second gears.

This style of riding will have you looking for a filling station after 109 miles. The petrol tank is not as capacious as it would appear. There is a large recess underneath where the air filter box sits but 3.7 gallons should give a decent range when riding sensibly.

Bolted to the downward-pointing inlet manifold and looking something of an afterthought is an oil-fed carb de-icer. A rubber pipe takes hot oil from the right-hand side of the cylinder head to the de-icer and the flow is regulated by a solenoid. This gizmo puts paid to the temperature drop problems caused by the rapid flow through the inlet valves.

The XJ600S is a difficult bike to judge. It can't be compared to supersports 600s on price or performance. It can't be compared to dual purpose machines because it is not one. It shouldn't be compared to Zephyr but it will be.