1981–1983 Yamaha SECA 750, XJ750RH-RK, XJ750K Service Manual (P/N 90890-03081)

• 309-page PDF set — a 250-page bilingual English/French Yamaha XJ750K manual for machines beginning with serial 22T-000101, plus a 59-page XJ750RH supplement beginning with serial 5G2-000101.
• Covers 750cc inline-four engine removal and installation, cylinder-head, cylinder, piston, valve-train, cam-chain, crankshaft, clutch, oil-pump, starter-drive, transmission, and middle-gear/damper repair, followed by factory reassembly and adjustment procedures.
• Walks through shim-over-bucket valve-pad clearance service, compression and ignition checks, YICS-assisted carburetor synchronization, fuel-level setup, idle adjustment, carburetor disassembly and inspection, and air-cleaner/crankcase-ventilation work.
• Chassis sections address front and rear wheels, disc and drum brakes, fork overhaul, steering-head adjustment, swingarm and rear-shock service, cable and throttle maintenance, and shaft-drive gear-lash inspection, disassembly, and reassembly.
• The XJ750RH supplement adds anti-dive suspension service, front-fork overhaul, computerized monitor-system diagnosis, starting, charging, ignition, lighting, and signal-system tests, model-specific cable routing, and an XJ750RH wiring diagram.
• Provides Yamaha special-tool listings with part numbers, assembly-specific torque data, clearances and wear limits, bearing and shim selection charts, lubrication diagrams, circuit schematics, troubleshooting charts, and exploded parts illustrations.
• Important scope limit: Yamaha identifies the factory supplement internally as XJ750RH and directs technicians to use it with the XJ650G Service Manual LIT-11616-01-94, which is not included. The added outer cover mentions XJ750RH–RK, but the technical pages do not contain a separate XJ750RK repair section.

Document Coverage

The 250-page XJ750K file begins with Chapter 1 rather than the original cover and publication pages. Its first technical page identifies the XJ750K and the 22T starting serial. The manual then runs through General Information, Periodic Inspections and Adjustments, Engine Overhauling, Carburetion, Chassis, Electrical, and Specifications, with English and French printed side by side.

The 59-page supplement carries Yamaha identifiers LIT-11616-02-34 and 5G2-28197-10. It is an XJ750RH model-difference publication rather than a complete standalone workshop manual. This set is therefore best understood as the XJ750K technical chapters plus the factory XJ750RH supplement—not as complete factory coverage for every RH/RK configuration.

Factory Repair Depth

The engine material goes well beyond routine tune-up work. Yamaha documents cylinder-head and cylinder removal, valve and valve-guide/seat repair, piston and ring inspection, camshaft and cam-chain checks, crankshaft runout, Plastigage oil-clearance measurement, color-coded bearing selection, oil-pump inspection, clutch repair, transmission and starter-drive inspection, middle-gear damper service, and controlled crankcase reassembly. One useful scope detail is that the cylinder head, cylinders, and pistons can be serviced without removing the complete engine from the frame.

The opening tool section ties these jobs to Yamaha service equipment. Examples include the tappet-adjusting tool 90890-01245, vacuum gauge 90890-03094, clutch-hub holding tool 90890-04086, damper compressor 90890-04011, front-fork cylinder holder 90890-33256 / 90890-01326, and pocket tester 90890-03104. These references help identify when a repair depends on a purpose-built holder, puller, gauge, or electrical tester rather than an improvised substitute.

Diagnostics, Diagrams, and Repair Notes

Electrical coverage includes the starter motor and cut-off relay, A.C. generator and regulator, transistorized ignition and pickup coils, sidestand relay, lighting, switches, battery, signals, and the self-canceling flasher system. The XJ750RH material adds a problem/cause/solution chart for the computerized monitor, plus dedicated circuit checks for the starting, charging, ignition, lighting, and signal systems.

Useful visual references include the XJ750K and XJ750RH wiring diagrams, anti-dive oil-flow views, the computerized monitor circuit and fault chart, charging-system circuitry, cable-routing drawings, and exploded illustrations for the clutch, transmission, middle gear/damper, final gear and drive shaft, wheels, brakes, front fork, meter, and electrical components.

The manual flags several model-specific repair traps. During valve-pad replacement, the cam lobe must be kept from contacting the tappet-adjusting tool or the tool and valve-lifter area can be damaged. Middle-gear reassembly also depends on correct damper-cam indexing and applying press force to the proper bearing race; incorrect handling can damage the gear or bearing assembly.

Engine removal, fork disassembly, brake repair, spring-loaded assemblies, and shaft-drive work require secure motorcycle support and the correct service tools. Follow the Yamaha cautions in the PDF, keep measuring equipment calibrated, and do not treat the manual as a substitute for the mechanical experience required for these repairs.