The main difference for me is the handling, the R100 just feels ponderous and slow after the R65. Not that my R65 is especially standard.
As far as speed is concerned, the R100 is not that much faster, surprisingly, perhaps the different gearing closes the gap at normal road speeds. But it does have longer legs for the longer run.
I am fighting the urge to modify the R100, but I must keep it reasonably standard as there is no point in having two Cafe Racers.
Is there? Gaaahh!
Cheers
Steve Hawkins