I have a scorpion 2208-24 (v1) motor with 10T pinion that I would like to put into my Blade 300x to see if there is a good improvement in power. However, it appears the stock ESC is not good enough or the settings are wrong for this ESC as it will barely get enough head speed to lift off the ground. I read that a 25A esc would be sufficient for this motor, which is what the stock ESC is labeled as. I'm very new with trying to match motors w/ ESCs so please help me figure this out. Is it just a timing issue and I need a different ESC? Are there settings on the stock ESC I could change to make it work? Bad motor?

Thanks in advanced

The problem you have is that your motor Kv is too low---I think about 3600 rpm/V vs the stock motor 4500 rpm/V. This is a gigantic difference. In principle, a 12 tooth pinion (vs stock 9T) would get the headspeed back up to a reasonable value, or you could go to a 4s battery pack. Both would give you back the ~75% difference in Kv.

Motor power ratings only means the motor will survive running that much power through it---it doesn't mean the motor will make that much power. How much power the motor can draw from the battery pack and deliver to the motor shaft depends on the voltage (and current capability) of the power source, and the load the rotor head is putting on the motor. In your case, with tht Kv, the load on the motor is just too low for it to pull the power out of the pack, with that voltage.

Whether the motor can survive that much power depends on the fraction of the "no-load" rpm it is running at, and the winding resistance of the motor. The latter is a function of motor size, for a given Kv, being lower resistance for the larger motor. The larger motor can also shed more heat due to the larger surface area.

This is probably more than you wanted to know. So short answer is Kv is too low.