ORIGINAL: ahicks

Any predetermined carb settings are only going to be good for some assurance the engine will start and run when set to them. They MAY be close to optimum - but please be assured there is no guarantee the engine will be running at optimum using them! Either one or both could run much better 1/4 to 1/2 turn, richer or leaner, from the predetermined...

They are meant as a starting point, meaning that if the engine won't start/run on them, there's something else going on. That's it. There are WAY to many variables to account for that use these adjustments to compensate.