Looking down the throat of the carb (.46 2-stroke), how much opening should there be at a decent idle? I assume full closed will kill the motor, unless there is enough air bleed through the low speed needle/air bleed adjustment on the throttle arm? Trying to set my throttle servo throws and get an engine broken in - I'm new to non-electric motors...

Depends how well tuned the engine is but normally it is opened just a little for idle. Take a "T-pin" or a small paperclip (opened up) and insert it into the opening and gently close the barrel against it. Make sure the throttle trim is at least half-way up . That will be a good starting point. Yes, when the barrel is fully closed the engine will stop.
Depending on the radio you have you can electronically adjust the end-points and sub-trim to get full throttle, closed throttle right. If not then you will have to make any adjustments mechanically.

Hi jnylund and welcome to the forum. Yes hopefully when the throttle barrel is fully closed the engine will stop. That does not always happen in the presence of air leaks. Any way you really need to state what make and importantly what model your engine is before anyone can be more specific.

So what is the make and model engine, is it new or used and do you have the operating manual for this engine??

John

perfect - thanks!

engine is o.s. .46LA, NIB for a Sr. Falcon trainer. Have all documentation, just didn't see anything related to my original question.

Here is the way I do mine and it seems to work out well. First have the trim control as low as it will go on the transmitter and the throttle at low. Set the servo arm so that it just closes the throttle barrel as far as it will go without any binding. Now set the throttle travel so that when the throttle lever is fully advanced, the throttle barrel just reaches it's limit. You may have to experiment a bit with the length of the servo arm to achieve these settings by moving in or out from the servo pivot point. Now, when you start the engine, you have to have the throttle trim open a bit, probably at about center position; just adjust for proper idle with the throttle lever at low. Now, you should be able to kill the engine when you move the throttle trim to low; a desirable thing to be able to do.

Now your cooking JN , Wallindas decription with the pin is pretty much what I do with bleeder carbed engines and Rodney method of setting the cutoff with the trim is also a time tested method. Some radios can program to do this cutoff but it still be setup mechanically the same as Rodney described.

I have one LA 46 left and they are extremely user friendly you will enjoy it. Mine does yeoman duty flying a heavy old plastic arf floatplane around but it seldom goes to the lake. I just launch it off a launch dolly and land on the floats in desert hardpan. A few strips of duct tape takes care of the keels

John

Hi!
1,5-2mm!