OS .21 Break in needle settings?
 

(About) How many turns out should the low speed and high speed be for my os 21vzb during a heat cycle break in?

Depends on what it takes to still be rich and actually warm the motor up. Throw some insulation around the heat sink, start at .5mm out like the manual says, set the idle at the factory position, then lean it out enough to get it started and keeping heat. Note that a race tune on the LSN is just about flush, so if you get to flush, you've probably gone too far. I had to lean mine out a bit to get it to run and spit fuel. Just start where the manual says and lean it until you can keep it going and building heat but still rich. It also depends on what pipe you have and the fuel you're using.

I break in all of my OS engines at factory settings. Sometimes you will need to lean the top end and or bottom end a few hours to actually get it to stay running, but other than that, factory settings. Don't lean it if it will run at factory. IMO the more fuel, the better for break in. Keep temps at around 200* F. If needed use a piece of tin foil and a heat gun. Always preheat close to 200* before starting.:nod: