Check for a torn intake boot between the head & carb. It's common for them to tear & it'll create a high rpm miss. Typically the cause of the boot being torn is engine mounts that are loose or broken so check for those too. One way I've checked the boot is to hold a steady throttle when you're up to speed & reach down & tug on the carb, it'll Prolly miss in areas that it didn't miss before. Btw, if this is the cause replace the boot with a Yamaha piece, you can get El Cheapo's from ebay but they don't last. Good luck.