Hey guys! 
I keep on having a problem while downshifting, usually from 4th-3rd, but also upshifting. I am new to bikes in general so it hurts me, even more, when I hear my clutch cranking while trying to put it in gear because as far I know and I feel it is in a good shape so I feel like I am destroying it... and most of all i feel in danger while driving fast and it happens. When i shift the pedal feels sharp and well lubricated. like a good maintenance gun. I recently changed my clutch cable but I had the same problem before. I do all the maintenance myself so feels even worse as this is the only problem I have. also happens while upshifting to the second gear but this one might be my lazy footwork.

First thought was that it's simply an old bike so the amount of slack for the new riders is short. I just have to do it the right way. So I figured the number of revs might be not correct. as I might still not be used to motorcycle engine - in a car, it's "2200" or somewhere right above 3000 when having fun. So I read on a forum the guys ride between 5k-7k and that's what the engine likes. I am trying to figure out the final drive ratio and simply on what revs to change gears upwards. I usually keep 1st and 2nd on 3k and then 3rd to 3-5k up to 80kmh.
the question is silly but I have no one on a K bike around: how do you shift? what revs?

I do rev-matching while downshifting. do you? 

or it might not be the case at all?

thanks!

Hi first things first,please enter the bike details including VIN number/mileage on the signature strip this will enable the brains
on the forum to give accurate advice.Have you set the clutch cable correctly?? if not all sorts of problems will occur.Should you have local contact with experienced riders ask if they can   
help out.Hopefully its rider error and not the clutch splines that need servicing 

These are symptoms that often indicate a maladjusted clutch or the need for a transmission input shaft spline lube, as moriarti has indicated. Determine if there is any play in the shifter, too. Tell us here how long you've had the moto, how many miles are on it and how many miles you've logged on it.

You're likely to be able to repair this yourself.

You need to be very positive with the shifts, short shifts work OK on the Japanese bikes but the Getrag gearboxes don't take well to lazy shifts. Also as said the missed shifts can be a result of dry splines on the clutch shaft.

Definitely check your gearbox oil level.  I checked mine recently and had to add about 100 ml or so (there was no measuring involved).  Not much but I think it has made a bit of a difference in shifting.  I usually shift at about 4k rpm's when going up through the gears and always blip the throttle when down shifting -  a small blip if I'm slowing down slowly and heavier if I'm engine braking.  Rick is spot on about lazy shifts and I believe Robmack has previously described the feel of the early Getrag transmissions as 'tractor like'.  Bring everything up to spec - fluids, adjustments, etc. and then see where you are at.

As noted above, false neutrals from 4->3 and 3->2 are usually a symptom of the need for a clutch spline lube.

Rick also has a point in that K bikes need to be shifted with authority.  You shouldn't be stomping on the shift lever though.

Do follow all of the advice so far...

I remember reading an article where the (female if I am correct) went to great lengths describing the benefits of applying (a little) pressure to gear selector pedal before pulling the clutch and going ahead with the gear change (ie. full pressure and movement). 

Also, in an English classic bikes magazine, the happy owner of a R75 described the gearbox as "agricultural".

I occasionally get false neutrals between 4 and 5 - I can only blame myself for a half hearted effort on the pedal.

GF

Hi 
Service your bike then ride. You're new to riding so in six months it will be better, before long you'll be doing this on auto pilot. Different tips work for different people and different bikes. Try changing at 3000rpm and a few others. Don't let the revs drop.  Try quick changes,  slow changes. Try with the clutch lever just half in. Try feeling the gear leaver in, instead of force,  but with pressure,  I know,  that's an oxymoron. The first BMW I rode had no problem at all, but I still get false with mine now sometimes, I don't care I just have a second go at it. Try different boots.

As stated by many before, use the pedal to its full extent.
Also, and nobody apparently told it yet, when you change your gearbox oil, disobey the instruction manual and use some 75w140. It makes a hell of a difference on those bmw rough gearboxes.

It's a hit'n'miss gearbox, a strong foot will help

Poupy wrote:As stated by many before, use the pedal to its full extent.
Also, and nobody apparently told it yet, when you change your gearbox oil, disobey the instruction manual and use some 75w140. It makes a hell of a difference on those bmw rough gearboxes.

And moly gear oil additive.  It's takes a few hundred miles to work in but it makes a noticeable difference in smoothing out the shifting.

A rounded tablespoon of 1.5 micron Molybdenum Disulfide powder in the gearbox oil will make it shift like a rice burner.

I use half a tube of this stuff:

Thank you all so much! 
i am silly jilly and wrongly adjusted clutch cable. it's all fine now but you have a point with spline lube and thanks for all the tips with the gearbox oil and working with the clutch!