My ’97 BMW F650 will supposedly put out 48 horsepower at 7500 rpm, but in practice I don’t cruise much over 5000 rpm (75 mph in 5th gear). Why? Vibration, engine sound, intuition and fear. Mainly fear.
Significantly, 5000 rpm is the smooth, high-power sweet spot for the F650 Rotax engine.
At 5000 rpm I can go up the hills typically found on the interstate or roll on more power to get past a truck. I can slow down a bit and then speed up without shifting. And the bike will keep it up all day long.
That said, I am usually more comfortable riding around 65 mph at about 4300 rpm. Everything feels more relaxed. I don’t have as much horsepower to work with but it is manageable.
But if I have to slow down to 55 mph for some reason, I will have to down shift to go up a hill or accelerate. At 3600 rpm, the engine isn’t putting out enough power to do those things in high gear. After all, the bike weighs about 430 lbs. and I’m 170 armored up plus about 60 lbs. of luggage. So about 660 lbs. total. And I have a big windshield pushing the air off me.
I do have stock sprockets, so if I changed the front 16 tooth for a 15, I would be running 5000 rpm at 70 mph. That might give me a machine that is better matched to my style of riding. Some of the guys on the F650 Chain Gang recommend the 15 tooth sprocket. I may try it.
I’m basing my thinking on a recent 6500 mile trip with much of it over 60 mph on a loaded bike.
If you are going to ride the interstate or the high speed two lane roads in the West, especially with a load, the kind of power I get from the F650 is probably a minimum. Otherwise, you will be shifting all day long and constantly reminded that you are on the wrong bike.
Even on the F650, the Road Kings rocket by me, their riders seemingly carefree with their feet stretched way out in front. They look like they’re watching TV.