Honda OEM radiator cap, 19045-MZ3-40, for GL1200 1985 Limited, 1986 SEI and 1987 Aspencade models and for GL1500, 1988 - 2000. Picture shows two views of cap but is sold as each.

Maintenance schedule: Honda advises inspecting the radiator and coolant core every 8000 miles or 12800 km. Replace your coolant every 2 years or 24,000 miles - whichever comes first.