I raise my left hand in a "how" position 100% when I see a fellow motorcyclists coming and get a 95% return wave....in many different configuratios. 50% of the HD passengers do the waving here, which works just as well.

Yesterday, on our weekly breakfast ride, we (11 of us) were on a norrow road and coming the other direction was 20-25 Harleys of the local HOG chapter. I waved for 1/4 mile it seemed...ha ha

Several weeks ago, returning from a Sunday breakfast, alone, I came upon a sport bike group. I waved, as most of them did, except one who did a wheelie as he passed in the other direction. Now, that was a wave!