Forgive me if this has been addressed, and I'm too thick to have found it, but the air cleaner chamber top (called the 'air duct' in the parts list) on my bike is missing about a third of the seal. What have you other fellows used for a replacement seal, please?
Nasty, Brutish, and Short
1967 Yamaha U5-E
1971 Honda CB175 Candy Gold
1972 Norton Commando 750
1973 Honda CB350F Candy Bacchus Olive
1975 Suzuki GT750M Jewel Grey
1975 Honda GL1000 Candy Blue Green
1976 Honda GL1000 Sulfur Yellow
1976 Benelli Sei
1979 Honda CBX Glory Red
1983 Honda CB1100F
You are NEVER too old for a happy childhood!