I have a 2000 Honda Varadero 1000 with only 7000 miles on and it’s developed a vibration. I've checked the tyre pressures and they are spot on. I have slackened the chain off a bit more, but to no benefit. Both sprockets are fine.
The wheels could be out of balance, especially the front one. There are balance weights on the wheel and if one has fallen off that will set up a drumming at certain speeds.