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The Yamaha XJ750 Seca was a sport-standard motorcycle produced from 1981 to 1985, featuring a 748cc air-cooled, inline-four engine, shaft drive, and Yamaha's YICS (Yamaha Internal Combustion System). 

Key Yamaha XJ750 Seca Models & Variants

  • XJ750RH / XJ750 Seca (1981–1983): The base sport-standard version featuring a distinctive rectangular headlight with a smaller auxiliary light below, anti-dive front forks, and an electronic voice/light monitoring computer tracking basic functions. [ 1,  2,  3,  4]
  • XJ750RJ Seca (1983): A "dressed" factory-option variant that included cleanly integrated, aerodynamic hard luggage side-cases. [ 1]
  • XJ750 Maxim (Companion Line): While the Seca focused on sportier ergonomics, solid motor mounts, and sharper handling, the sister XJ750 Maxim model leaned into custom cruiser styling with pulled-back handlebars, stepped seats, and rubber-mounted engines. [ 1,  2,  3,  4]

     

    The factory primary body colors for the Yamaha XJ750 Seca (1981–1983) included Maxim Red (Cardinal Red) and Quartz Silver Metallic, depending on the model year and regional market. [ 1,  2,  3,  4,  5]

    Primary Body Colors & Paint Schemes

    • Maxim / Cardinal Red: A vibrant multi-stage factory paint process utilizing a bright metallic silver base coat followed by translucent candy red layers. Additional coats deepened the red shade into a rich candy finish. [ 1]
    • Quartz Silver Metallic: A high-gloss bright silver metallic coat used extensively across multiple production years. [ 1]
    • Accent Graphics: Both colorways featured bold factory black accent stripes and geometric block graphics layout across the fuel tank and side panels. [ 1]

      Frame and Component Finishes

      • Competition Yamaha Black (Code 33): Used as a semi-gloss or metal-flake black on the frame, engine brackets, and select chassis components.
      • Flat Black (Code R4): Applied to functional parts like kickstands, center stands, and footpeg brackets.
      • Lower Fork Tubes: Finished in specialized silver/black highlights depending on production batches. [ 1,  2]

         

        Engine Specifications

        • Engine Type: Four-stroke, transverse inline-four, DOHC, 2 valves per cylinder
        • Displacement: 748 cc (45.6 cu in)
        • Bore x Stroke: 65.0 x 56.4 mm
        • Compression Ratio: 9.2:1
        • Cooling System: Air-cooled
        • Horsepower: 76–82 hp @ 9,000 rpm (depending on regional tuning/year)
        • Torque: 49 lb-ft (66 Nm) @ 7,500 rpm
        • Fuel System: Four Hitachi CV 28mm or Mikuni carburetors (with YICS system) [ 1,  2,  3,  4,  5]

          Transmission & Drivetrain

          • Transmission: 5-speed constant mesh
          • Final Drive: Shaft drive [ 1,  2]

            Chassis & Suspension

            • Frame Type: Tubular steel cradle frame
            • Front Suspension: Telescopic forks with adjustable anti-dive
            • Rear Suspension: Twin shock absorbers with 5-position spring preload adjustment
            • Front Brakes: Dual disc brakes
            • Rear Brakes: Mechanical drum brake [ 1]

              Capacities & Weights

              • Dry Weight: Approx. 500 lbs (227 kg) / Wet weight around 525–538 lbs
              • Fuel Tank Capacity: 19 liters (approx. 5.0 US gallons, varies slightly by market/year)
              • Oil Capacity: 2.8 liters (with filter change) [ 1,  2,  3]

                If you need more specific details, let me know:

                • Are you looking for fluid capacities / maintenance intervals?
                • Do you need torque specs for engine assembly?
                • Are you troubleshooting a specific carburetor or electrical issue?