Hi guys

I am lucky enough??? to now own 2 K 100 rt,s

My 85 model does 4000 rpm at 100 kph

And my 89 k 100 rt Ex police bike does 4700 rpm at 100 kph

32/11 is stamped on both diff housings??

My question is

Do police K100 rt,s have different gearbox ratios???

hi,

If you look here at this rpm to speed calculator (also an office 2003 ver there)


http://e1ferq.bay.livefilestore.com/y1pRoZtqpnPaVyBlRjqZKpWg31fwkmCmDxxEFuVmUQ4-ok8OHBZl1186uvGwHlWTlNudNzslcbK7UFN5z5_QP0mKw/Speed%20to%20RPM%20calculator%202.0.xlsx?download

Then.
Assuming 5th gear, same road and same external conditions (wind, rain and so on) in both cases.
then using excell "goal seek" one gets that given 5th gear with a 32/11 final drive and with speed set at 100KMH - calculated RPM under ideal conditions should be 3792. this is in agreement with your 85 bike as in real world there are loses such as drage, tire charachtaristics and so on.

again using excell "goal seek" - to get the 100kmh at 5th gear with final drive at 32/11 5th and 4700RPM, gear would have to have a ratio of 2.065 instead of documented 1.6660.
This is some where between 3rd and 4th gears, those more knowldgable then me will have to pick this as I have no idea if what you say agrees with known specs.
one possibility is tire differences but the disparity seems too large to me to be explained by tires, it certainly is not size as you could only get these results if tire circumference goes from ~213cm to ~171cm (ie diameter down from ~67cm to ~ 54cm)

can you pls do similar tests in other gears?

Roy

Hi Roy

Thanks for the reply

I have just bolted a gps on and went for a ride on the 89 model, and the speedo is out a little (Bike 97k = gps 100k) so that brings the revs down a little,, Tacho reads an indicated 4500 to 4600rpm at GPS 100k, I wonder if the diff has been altered internally but not restamped,or the rev counter is out of wack???

Both tyres are new.

85 is Metzeler ME88 130/90/17
89 is Michelin Macadam 130/90/17

any ideas???

Thanks skip,,

Hi Skip based on Roy's calculation I would be suspecting a tacho error but how does it feel as there is a certain amount of vibration between 3800 and 4500 so that might give you a better comparison.

I would suspect if anything would have been changed it would have been the final drive to improve acceleration overall but not to the extent you mention and that does not appear to be the case with your bike.

Regards,

Phil

According to the ETK, authority K100s (Police bikes) don't have a different crown gear.
However, ETK is listing 2 different ratios for all K100rt from 1984 to 1989: 33/11 and 32/11
Was the 33/11 an option????

Phil

Thanks for the reply. Ill try to find a portable rev counter and see how accurate the rev counter is on the 89 model, It seems ok with no jumps or stuttering, but the bike does seem to be reving harder than the 85,

Bert
The only marks on both diff housings is 32/11 so I may have to swop them to see if there is any differences before tearing them apart,,.

Might take a while but Ill let you know if I find out anything,

cheers

skip,,

Swop the speedo's first. A lot easier.