Hi there again
There is the movie that will show everything better that thousand words:
https://www.youtube.com/watch?v=8uWburs0V24

I have no idea what can cose that problem because linkage has a free play, nothing clogg the free movement. Looks like a spring is not closing baterfly (but all springs are ok) but how? All is ok.

I'm sure the explanation must be very simple but looks like I'm to stupid to find one. That is why must be supported

Make sure  the Choke/ fast idle cable is not stuck and pulling/holding the throttle open.

moriarti wrote:Make sure  the Choke/ fast idle cable is not stuck and pulling/holding the throttle open.

Done already, a lot of free play.

Things to try:

It may be the TPS holding it open.

Also lube the throttle gears in the throttle perch. (I get rid of the old grease and use spray silicone instead.)

Try adding some slack where the throttle cable leaves the throttle perch.

Make sure that the grip rubber is not rubbing against the throttle perch. (or bar end if there is one)

Spray some silicone grease in the TB springs.

Hi Piotr, few years ago you posted a engine noise  problem on this forum, but never finished. What happened, did you solve noise. How?

duck wrote:Things to try:

It may be the TPS holding it open.

Also lube the throttle gears in the throttle perch. (I get rid of the old grease and use spray silicone instead.)

Try adding some slack where the throttle cable leaves the throttle perch.

Make sure that the grip rubber is not rubbing against the throttle perch. (or bar end if there is one)

Spray some silicone grease in the TB springs.

Will try TPS but just made adjustments and looks ok.
Believe me all linkage, places where linkage goes were several times lubricated and everything plays free. Only the throttle behaves as the spring did not close butterfly completely. I think I should looking for problem in there, but TPS also looks somehow reasonable

duck wrote:Things to try:

Also lube the throttle gears in the throttle perch. (I get rid of the old grease and use spray silicone instead.)

Try adding some slack where the throttle cable leaves the throttle perch.

Spray some silicone grease in the TB springs.

Came here to say make sure there really is free play in the cable, when I first got my K I couldn't figure out why I had to set the cable to have loads of slack before the revs would fall quickly down to idle and it was because the gear wheel with the chain on it was heavily worn, which adds a lot of slack to the movement.

Also, some kind of grease (or I'd start with light oil) on the TB springs is easy enough to try.

Do the revs fall back to idle speed quickly?

Make sure the cable is not jamming in the cable channel where it attaches at the TB's.
Regards Martin.