Usually, US model vehicles have lower final drive ratio to cover long distances while keeping the rpm lower. And European models of same vehicle has just a bit higher final drive ratio and hence give bit better acceleration but less top speed. And i heard it is done considering the distances a...
Try at 2. And do cold start in the morning. If engine hesitate getting rpm, open a bit. If it seems solid, then you may tight it further 1/8. Do not lean it unnecessary.
Richer 10,000 miles are less damaging rather 10,000 miles of too lean.
Plus let it warm up well, if you want it bit on...
If you are getting high voltage on idle, and low voltage on higher RPM then it is your voltage regulator. It is easy to figure out, by cliping in other bike's regulator for a minute and you 'll get the results.
Indeed it is clever way to set the screws. However, if one have good ears, then screws can be adjusted in old traditional way and that too works fine.
Thanks for the info though.