Well. I have a OS .46FX and 40LA. Both engines have the standard needle valve, a screw sticking out of the carb and I'm assuming the idle adjustment on the side of the carb.
What do all these screws do? And how do I adjust them for best performance. I'm pretty familier with the needle valve and have learned to run it on the rich side, due to a engine failure on takeoff.
Is there a engine tuning website somewhere?
Thanks folks.
Wade

It comes up on here all the time. Do a search for needle maybe?

The low speed needle on the LA works backwards because it is an airbleed. Set It where the screw protudes half way into the little hole on the front side of the carb. That will be a good place to start.

Jim

Hi!
Tuning model engines are really very simple .......All engines have two needles! One highspeed needle that adjustes the rpm of the engine...and a low speed idle-needle that adjusts how the engine responds to throttle action and idle-speed.
The cheaper smaller engines like the OS LA and FP series have an airbleed idle-needle which more or less could be forgotten because it does not influence idle action soo much, The carb works perfectly as it is and the only thing you have to adjust is the highspeed needle (more or less anyway).
The more expensive engines have an idle-needle that restricts fuel entering the carb...thus making the idleadjustment more fine and precise.
This is how the needles work! But ....you have to learn how too set them by listening too how the engine sounds...to lean ...or to rich .


Good luck!
Jan K
Sweden