this motor has 150 hrs on it , carbs cleaned, new fuel line,tank,filter,seperators,will run up to 5500 rpm and when returned to neutral will only return to 2200 then eventually to 1100. how do you make adjustments ?
You should get a yamaha service manual these carbs have a lot of settings.
It seems like the linkage might be hanging up. Check your dashpot setting there is an adjustment screw. Are all the throttle valves able to fully close???
Without a manual you will have to eyeball the linkage to see why the idle stays so high Also check where the main throttle cable connects to the engine you can make adjustments there. good luck
Get a twenty dollar vacuum gauge and hook inline just in front(before) engine's filter....vacuum should never go over 4", if it does you have something
wrong with your setup....sounds like a vacuum buildup.