Welcome to more information than you probably wanted. For the engines you questioned (46 to 61 2 strokes) the OS #8 is all but foolproof. Don't go to extremes with the fuel. I normally run 15% Heli with 2 OZ of Castor Oil added. The castor oil is added to give some protection if a slightly lean run is encountered. Heli fuel is all synthetic lubricant and breaks down at high operating temperatures. This gives a good range of power and ease of running without being difficult in most weather conditions. Don't run the engine "lean" as it won't produce more power it will just wear it out. I have an Enya 50 with more than 500 flights and no visible signs of wear or discoloration using this system.

Now for the idle bar: This was an answer to early engine designs that dumps most of the fuel charge directly at the glow plug. It is un-necessary with modern engine designs. Probably still available since people get used to a specific product. It took me a while to understand this and make the switch. Read articles in magazines and/or read Dave Gierke's book on 2 strokes.

EXCAP232