Hello, I put the newly acquired k100rt back together today after sorting out a couple of stray wires. Took it for a little ride and noticed that it seems to be geared rather low, just by the sound of the engine in fifth gear.

At 45mph the tachometer is turning 3000 rpm, is that normal for a k100rt... seems its reving fairly high at that speed, feels like it's geared kind of low. I believe there's a gear ratio stamp on the rear end somewhere,will have to look and compare it to the owners manual.

Any thoughts on this topic will be appreciated. thanks bob

not sure but you may want to look at the diff ratios. stamped on the diff at the point where shaft drive connects.

From memory there are a number of different ratios you can have, but can you interchange them?

It's probably because I'm not use to riding a K bike, use to two cylinders that lug a lot. One of the aircraft mechanics here where I work use to work for a BMW shop and he said the K bikes have a short stroke and like the higher RPMs. He said to keep the RPMs up around 3k+ and to not let it lug.

I will check the ratio numbers on the rear to see if it's in line with the manual. Thank you

Yes, the torque does not kick in until 2500rpm and in my case she complains if I try to do anything under 2500. I tend to keep my rpm around 3000 so choose a gear to suit. At 60km/h (local streets) i never get out of 4th.

The ratios are:
K75 (all models) Standard 32/10 (3.20:1), optional k75S 34/11(3.09:1) and 37/11 (3.36:1)for the other models

K100RS 31/11 (2.82:1) , optional 32/11 (2.91:1)
All other models K 100, 32/11, optional 33/11 (3.00:1)

Those spec are for European models. I gues they're the same for the rest of yhe world

green cat wrote:The ratios are:
K75 (all models) Standard 32/10 (3.20:1), optional k75S 34/11(3.09:1) and 37/11 (3.36:1)for the other models

K100RS 31/11 (2.82:1) , optional 32/11 (2.91:1)
All other models K 100, 32/11, optional 33/11 (3.00:1)

Those spec are for European models. I gues they're the same for the rest of yhe world

Thank you. Just to get this clear in my mind: 2.82:1 goes fater than 3.00:1 at say 3000rpm... correct?

I don't think so... 3.00:1 is faster than 2.82:1

I think mine is doing about 3800 at 100k's or 62 mph and they are an undersquare engine so definitely not a short stroke and no need to be revved like a Jap bike.

As Ned says from around 2500 things start happening which is pretty good for a four cylinder and from 3000 no problems at all.
You can open the tap at 3500 in top gear up a very steep hill and away it will go.

My old CB900 did not get going till the tach hit 7000 and the XL1000 I took for a run recently was doing about 3000 rpm at 80 k's in third gear with three to go!

So the K is no Harley but it still has plenty of torque and no need to row the gearbox to keep it going.

Regards,

Phil

I checked my rear end and it's 32/11. As for which gear ratio is faster, as in top speed, the 2.91-1 is faster than 3.00-1. For drag racing it's typical to use a low geared rear end, 4.56-1 4.11-1 etc.

Now the engine will rev faster with the lower gear ratio, but the top speed will be reduced considerably. The bigger the number the lower the gearing... ring gear turn 1 revolution to multiple turns of the pinion gear (engine tranny). thanks.