If so, is the bad news that absolutely nothing happens when I screw on the screw. I can screw it as far as it goes but it does not affect idling at all. the only thing that happens is that the throttle control is sluggish and will only half , if I screw it out a little so goes the throttle fine again ...

 

Then you probably have the throttle cable adjusted too tight or the thumb throttle may be sticking,etc. I'd just have someone look at it if you can't get it adjusted right.

 

yes it is not easy to explain to someone who does not understand ....
but I'm pretty stubborn of me , then you have the patience to guidea me , I will resolve this to the end.

 

Ever figure it out? Long shot of an answer but I’m having the same problem.