Service Suzuki QuadZilla LT500R 1987 1988 1989 1990 contains maintenance schedule and the repair procedures you need.
The Repair Manual for Suzuki QuadZilla LT500R contains:
General Information
Periodic Maintenance and Tune-up Procedures
Engine
Cooling System
Fuel Systems
Electrical System
Chassis
Service Information
Appendix
LT500RJ (88-Model)
LT500RK (89-Model)
LT500RL (90-Model)