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.

This thread is there already with just about the same title. So, I'll just latch onto this one. Unfortunately the YouTube video is no longer available but my issue is the following:

The bike will idle perfectly. Then after a while at a traffic light start to idle slower and slower until it stalls. Sometimes it will even idle a little faster. This happened after getting the K75s into shape.

I purchased the K75s in Cape town. It was idling ok and was running well. But the trip home to Pretoria was costly with a fuel consumption of 14km/l. (Just more than 220km on a tank) It got a good dose of injector cleaner and valve ease along the way. In many ways it needed a clean-up, service and repairs. (even a welsh plug) The handle bar was bent and eventually I found out that the triple clamps were not true too. Accident ..... fortunately I have a doner K75s.

After all the work, I did the 3600km eastern Cape trip, and the bike performed well, except for the idling problem and the front forks. The fuel consumption was steady 19km/l.

The TPS was not set correctly, which I corrected, checked compression, valve clearances, plugs, water temp sensor, cleaned the TB and checked for air leaks and the Z breather pipe. Checked the AFM resistances as per the info I found on the forum. I changed the injectors (Bosh EV14 multi port) because I thought that they may have something lodged or loose in them changing the fuel quantity. In the mean time had the original injectors tested and they a are good. Fuel pressure and delivery is good too.

Now I am at a loss of ideas or options and am hoping some light may come from the forum?

Greetings Rolf

Yeh... Problem solved.  

The only thing that I could still think of was that there must be some fault with the air flow meter. So I started with opening and measuring a spare unit that was dirty (came in a box with spares) and checking it according to Beamer's thread on air flow meter restoration. Everything looked fine, I cleaned the unit and at the same time also the air bypass. Doing so I checked the turns on the air screw before taking it out. The O-ring on this unit was perished . . . . so let me check the O-ring on the unit on my bike and compare the number of turns it is out.

Ha ha ha ... the air bypass screw on my air flow meter was turned tightly in the closed position. Since I don't have a CO analyser I checked on the forum what the +/- turns can be and this confirmed that the 4 3/4 turns on the spare unit was in line. I turned mine out 4 1/2 turns and bingo, the bike is idling well after resynchronising the TB. It is amazing that it actually still idled. 

What a fool I am to not have checked this from the beginning and assuming people don't fiddle there and the CO must be sort of right by checking the condition and colour of the spark plugs.  

Assumption is foolish
Trust is good
Check is better

:tu1:well done, mate!

Thank you for sharing the solution of this puzzling problem.

PS:
you wrote: 'Assumption is foolish'

the other day, I heard that one from a teacher:

ASSUME
makes an
ASS of
U and
ME

BTST:
I've ran into more than one difficult situation myself just by assuming I knew what the problem was.
And I had to say this classical quote to myself in the end:
https://youtu.be/0srO4LTzVTE

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

I just went through this with my K100RS. I found that when I had shortened a cable, a K75C, I had cut through the liner. I then removed from the liner, the same amount that I had cut from the casing. I then just slipped the liner piece with the "top-hat" into the cable into the top. Over time the liner migrated down and ended up in the throttle body cam, "cable channel".



The result was the liner walked down into the throttle body cam.



I first tried putting back in a K100RS cable but too short so I decided to re-work the K75C cable instead. I drilled out the cable barrel at the throttle body end, then pulled and reversed the liner. This time I heated the liner end at the throttle end,  with a circuit board heater/solderer, making my own top-hat by heating and forming with the blunt side of a razor blade.




In addition, I put two 2.5mm wide zip ties on the cable just in case the liner moves again. I placed them adjacent to the throttle cam and verified that they didn't impede full throttle opening.



This is now the exposed part of the liner.