Does the 85 K75 transmission have all the gears rotating on the mainshaft or are all 5 gears fixed... My curiosity is whether or not you could install a taller 5th gear without touching any of the other gears or the final drive. BMW seems to like having the top two gear ratios ridiculously close to each other for some reason. I've always wanted very tall top gears on all my vehicles (2-wheel, 4-wheel, etc.) As an example, I have a Honda XR650L DP bike that I'm gonna change the 5th gear from an 0.84 to an 0.80 ratio. Is there anyone in the world who knows of something similar for this K75? The 5th gear on the K75 is 1.66, while the 4th gear is 1.88. If I could obtain a 5th gear that was more like 1.5, or even 1.4 I'd be a very contented rider.Thanks, Frank

Put a K1100 gearbox in they have a 1.61 top gear and a K100RT/LT rear drive which makes a big difference. However just let them rev they do it willingly and changing gear ratios will do little but drop the revs a bit.

What RickG said.

These engines have been designed and tested to run non-stop at full load at redline for 24 hours.  They love to rev.

When I got my first K bike I was constantly reaching for 6th gear; a few years and several thousand miles later I now find myself doing 65mph on the interstate in 4th.

Buy a Toyota Camry. They love to run at 2500 RPM.

duck wrote:Buy a Toyota Camry. They love to run at 2500 RPM.

And they suck more gas than a K100.

Crazy Frog wrote:

duck wrote:Buy a Toyota Camry. They love to run at 2500 RPM.

And they suck more gas than a K100.

Even worse they only move the body.
A K moves the soul as well.

If you're worried about stressing the engine/gearbox, Mick Walker's 'K-Series Motorcycles' states in it somewhere that the drive train was designed and tested to run at somewhere in the region of 175bhp.

Guess that's how Luftmeister got away with fitting turbochargers without modding the guts of the engine.

frankie177rg wrote:Does the 85 K75 transmission have all the gears rotating on the mainshaft or are all 5 gears fixed... My curiosity is whether or not you could install a taller 5th gear without touching any of the other gears or the final drive. BMW seems to like having the top two gear ratios ridiculously close to each other for some reason. I've always wanted very tall top gears on all my vehicles (2-wheel, 4-wheel, etc.) As an example, I have a Honda XR650L DP bike that I'm gonna change the 5th gear from an 0.84 to an 0.80 ratio. Is there anyone in the world who knows of something similar for this K75? The 5th gear on the K75 is 1.66, while the 4th gear is 1.88. If I could obtain a 5th gear that was more like 1.5, or even 1.4 I'd be a very contented rider.Thanks, Frank

I'm busy looking into R1200C gears ( 2,54 ratio ) onto my K. I've found an R1200C bevel drive for sale but I doubt it'll all fit, so does anyone have just the gears ? If I get it right, my 2,82 ratio will probably go to my brother in laws' K75R, and them we'll see what he says about that.

Between a K75 and the four cylinder Ks the only difference in the transmission is 5th gear where the K75 is 1.67 and the 4 cylinder Ks are 1.61 - a little less than a 4% difference.

If you want the tallest final drive gearing that is sure to fit then you should convert the K75 to paralaver and use a K1 final drive which is 2.75. (33/12)

(But you'll end up with a really slow K75.)