Can't keep idle set

[patrick_dolce]

Hello, I am new to this page and I was hoping to find some answers to my issue. I have an issue where my 1981 cb750k will idle fine (900-1,100 rpm) when first started. If I use the throttle and bring the rpms up they tend to stay around 2-3k which is quite high. The weird thing is that i can thread out the main idle knob and the rpms will come back down. It seems like it is threading itself in when I use the throttle and is preventing the throttle plates from returning to a low enough position. All ideas are welcome and appreciated. Thank you guys!

 

[amc49]

If you have the OEM spring on the idle setting knob I assure you it is not moving.

You have the throttle set too high. The engine should never idle when stone cold, you only set the knob for hot engine only. It is SUPPOSED to die when cold, keeping a cold engine running until it gets warm is a learned biker skill.

Reset the knob for hot idle at same lower speed and leave it alone after that. When you set it to idle cold it is too far open for hot and why the engine races up.