What did the Yamaha factory use on the RD side enging casings to adhere the metal badges.
Even after almost 50 years they were very hard to remove.
Large round YAMAHA ignition cover and rectangular YAMAHA opposite side
Contact cement as far as I know. When it dries up for 50 years it's like the old Permatex hardening gasket sealant. Need an air chisel to get it off.
IR8D8R