For the 1987 VMAX coded VMX540L, the factory reference is Yamaha LIT-12628-00-80, a book that covers both the 1986 and 1987 machines.
It is a narrow span, which is good news when you are chasing a specification: there are few year-to-year exceptions to trip over. Still, confirm VMX540L on the frame, since the 1986 sled uses a different code and some tables are keyed to it.
The manual works through periodic maintenance, then engine service with the disassembly order, measured limits and torque figures the factory specifies. Carburetion and oil delivery follow, then the clutch, chaincase, track and skis, then front and rear suspension and the chassis. The electrical chapter carries complete wiring diagrams and the test values for ignition and charging components, and troubleshooting tables group faults by what you can observe.
