Can a non-overdrive tranny be upgraded to overdrive?

[BoxerSteve]

I have been told you should not be cruising under 4000 RPM . If I fall under 4K, I downshift to 5th gear so the engine isn't lugging or loading the driveline. I went from a 31/11 (2.81) to a 32/11 (2.91) and would never go back. I am reading 4200RPM @ 78MPH. My sixth gear is now a part overdrive, part 6th gear.

I generally try to keep the revs above 3,000 RPM. If below that, you are not necessarily lugging the engine. It depends on how much gas you are giving it and what gear it is in. High loads at low RPM = bad.

[gregor]

As I said earlier I get around 70mph at 4000rpm. Even running at 80mph (on a private test track) the bike feels fine.

I do have a regrettable habit of getting into 6th gear ASAP though- it simply pulls so well. Even on the twisty bits 5th gear is plenty accelerative. I tend to short shift through the gearbox at 4000rpm when in a moderate hurry. Must think it's a diesel like my car.

[Biff's R]

There isn't a cheap or easy way to change out the 6th gear. Just enjoy the extra passing power of running 500 rpm higher, but in a better spot in the torque range.