Yamaha XJ550 Seca

File:Yamaha-XJ550-Seca 1.jpg
Yamaha XJ550 Seca
Manufacturer	Yamaha
Production	1981
Class	Standard
Engine	Four stroke, transverse four cylinder. DOHC, 2 valves per cylinder.
Compression ratio	9.5:1
Top Speed	178.6 km/h / 111 mph
Ignition	Battery powered inductive
Transmission	6 Speed
Suspension	Front: Telescopic coil spring forks Rear: Swinging arm with dual dampers adjustable for preload
Brakes	Front: 2x 267mm discs Rear: 182mm Drum
Front Tire	3.25-19
Rear Tire	110/ 90-16
Weight	205 kg / 450 lbs (wet)
Recommended Oil	Yamalube 10w-40
Fuel Capacity	15 liters / 3.9 US gal
Manuals	Service Manual

It could reach a top speed of 178.6 km/h / 111 mph.

Engine

The engine was a Air cooled cooled Four stroke, transverse four cylinder. DOHC, 2 valves per cylinder.. The engine featured a 9.5:1 compression ratio.

Chassis

It came with a 3.25-19 front tire and a 110/ 90-16 rear tire. Stopping was achieved via 2x 267mm discs in the front and a 182mm Drum in the rear. The front suspension was a Telescopic coil spring forks while the rear was equipped with a Swinging arm with dual dampers adjustable for preload. The XJ550 Seca was fitted with a 15 liters / 3.9 US gal fuel tank.

Photos

Yamaha XJ550 Seca

Overview

Yamaha XJ 550R Seca

Labels arerelative.Though the Seca hasn't changed mechanically, it's drifted from sport to mainstream— in comparison, of course, to the competition. Superbikes with their claim to 11-second quarter-miles and outrageous top speeds—dominated the Seventies. In a similar way, middleweights are laying claim to the Eighties. Capable of mid-twelves in the quarter, with agility unrivaled by full-liter bikes and, maybe best of all, carrying price tags well below three grand, the best of the 550s are attracting sport enthusiasts like never before. Kawasaki opened up the '80s with the introduction of the KZ550—faster than any of the other middleweights except Yamaha's 650 Maxim.

The KZ's only class rivals (the Honda 550-turned-650 and the Suzuki 550) were mildewing with age, designed in the early- to mid-'70s with only minor subsequent updates. So along came 1981, and Yamaha sprang the Seca on us, which was competitive with Kawasaki's refined KZ and new GPz. But technology (thankfully) keeps blossoming: the GPz got better in 1982 while the Seca dropped back a notch. Still, the Yamaha ranked above the musty Honda and Suzuki middleweights. Nineteen-eighty-three — and, oh what a difference a year makes! The Kawasaki GPz has been refined, Suzuki's 550 is all new (with racetrack-inspired styling and technology), and Honda's new Nighthawk 550 and 650 are fast, fast, fast. And the Yamaha Seca? It is, basically, an '81 bike with more sedate styling. Less its handlebar-mounted sport fairing and flashy red-on-white paint scheme, the new Seca comes only in black with red and purple stripes. Following an '82 change, the front fender and fork sliders are color-matched to the bodywork.

This latest Seca has more mainstream appeal, though its sporting potential is still commendable. Moreover, it remains the lightest and narrowest four-cylinder bike in its class. Mechanically, the Seca is unchanged from the original model. The narrow engine design, made possible by mounting the alternator on top of the transmission case, was an important step in creating a more compact, lighter motorcycle. Honda is just now using that design on the new Night-hawks. Narrow engine cases do more than just improve Ground Clearance; ergonomics improve as well. With a narrower engine, the footrests can move in closer to the fore-aft center line of the motorcycle.This enables the pegs to be mounted low, allowing a fairly expansive seating position while still maintaining good cornering clearance.

Though modern in design, the Seca's twin-valve double-overhead-cam engine lacks the development of other manufacturers' mid-sized fours. Quarter-mile performance strongly reflects an engine's output, and here the Seca falls behind. Its quarter-mile figures—13.05 @ 98.46—pale against those of the current 550 King, the GPz. Kawasaki's rocket will blast through the quarter in 12.7 seconds at 103 miles per hour, while offering the same versatile power as the Yamaha. The Seca uses a straightforward chassis design. With 27 degrees of rake, 4.29 inches of trail and a 55.5-inch wheelbase, the 550 promises a cross between agile and stable handling, and it makes good on that promise. The Seca staggers very little in crosswinds, and the bike does nothing to surprise the rider; it just plain works well. Though its suspension components lack air assists and adjustable damping, the Seca accommodates most riding styles and handles most conditions well—exactly as a mainstream motorcycle should. The Seca's seating position falls between traditional and sport. The handlebar's pullback invites an upright riding position, and, fortunately, the instrument nacelle is high enough to act as a decent windbreak; the traditional-style handlebar won't cause wind-related discomfort unless you regularly cruise at supra-legal speeds. The footpegs, mounted halfway between sport and traditional, complement the seat-bar position well. A comfortable seat allows easy cruising for an hour or all day; the short step leading to the passenger area is small enough to let tall solo riders scoot back easily. History seems to be repeating itself, with just a change in characters. A few years ago the Yamaha Seca was the fresh face in the crowd of middle-weights while the Honda and Suzuki were the tried-and-true standbys. For 1983 the roles are reversed: the Seca has established itself as a solid performer by providing good power and handling all around (but not the best in class), while the new bikes are waiting in the wings to prove themselves.

Source Cycle

Make Model	Yamaha XJ 550R Sega
Year	1981
Engine Type	Four stroke, transverse four cylinder. DOHC, 2 valves per cylinder.
Displacement	528 cc / 32.2 cu-in
Bore X Stroke	57 X 51.8 mm
Cooling System	Air cooled
Compression	9.5:1
Induction	4x 28mm Mikuni carburetors
Ignition	Battery powered inductive
Starting	Electric
Max Power	37 kW / 50 PS @ 9000 rpm
Max Torque	41.9 Nm / 4,3 m-kg @ 7500 rpm
Transmission	6 Speed
Final Drive	Chain
Front Suspension	Telescopic coil spring forks
Front Wheel Travel	137 mm / 5.3 in
Rear Suspension	Swinging arm with dual dampers adjustable for preload
Rear Wheel Travel	80 mm / 3.7 in
Front Brakes	2x 267mm discs
Rear Brakes	182mm Drum
Front Tire	3.25-19
Rear Tire	110/ 90-16
Wet Weight	205 kg / 450 lbs
Fuel Capacity	15 liters / 3.9 US gal
Consumption Average	55 mpg
Standing ¼ Mile	13.4 sec / 98 mph
Top Speed	178.6 km/h / 111 mph