The OS .12 TZ I'm wanting has a 3 needle slide carb.
I've never messed with one of those.
I've heard the 3rd needle called the mid range needle but I've heard it wasn't.
I've also heard to leave it alone & that it can help to adjust it.
What's the actual story on the 3rd needle??

A recent Magazine had a story on 3 needle carbs but I can't find it, anyone remember what mag & what month it was in???

3rd needle , mid range.

Do not touch, unless your a really really good engine tuner and you have your motor fully tweaked. You can then fine tune it just a tad more.

But everyone says dont touch it. Reason being from what I heard is the factories flow test each engine and set the needles accordingly. I know I wont be touching mine soon and when I do Ill be making a mark to let me know where it exactly was. So I can always reset it.

Also this might be the article.

http://rcnitro.com/rn/articles/ht_tunengine_01.asp

Check at the very bottom in the red.

No that wasn't the article I was thinking about, The one I remember was a couple of pages on just the 3rd needle.