That's determined by the final drive ratio. Being a police bike, the dept could have ordered them special like that. Or, it could have been swapped as an entire unit. Single-sided final drives lead a very tough life. The internal ratio should be stamped into the cover near the drive shaft housing joint. Check that number against specs.

On my 1993 R100GSPD it turns about 4,500 + at 75 mph. Closer to 5,000. Seems pretty low gearing and I'm constantly having to push to keep up to interstate traffic.

My R100RS had much taller gearing. Does this sound right?

I know, nothing wrong with slowing down a bit, but nice to blow by tractor-trailers...

"push" what? Your are riding a 998cc engine, no lack of power. Granted it's a barn door and geared to climb steep dirt hills. But wind that motor to 6500rpm when passing is needed. Actually you can ride it there all day long.

"Wind the motor to 6,500 rpm..."

I really like that response and punch myself for being a wimp. Might be my R90/6 goes along at much lower revs. The GS is a specialized gearing with tons of low end torque, but it's got the power so I need to learn to use it.

What you shouldn't do is ride it at RPMs less than 3000, that's lugging the engine.

This is a true statement.