The cover protecting/covering the radiator fill cap is not gasketed. There is no place for water leaking in to the recessed area in the dash to escape. Drill a tiny hole in the lower right-hand corner of the recessed area so moisture/water can escape.
ps
I'm not trying to be a "know-it-all". I was the "Product Validation Specialist" at Yamaha Motor Corporation, Cypress, CA in 1980. One of my job functions was to critique motorcycles being released to the American market.