Generating 3-phase sine wave..

[skimask]

So, When I set timer1 to 64386 (1:1 prescaler @ 20MHz), it should interrupt at ~4.32KHz and create de 60Hz sine wave... but, it is generating a 26Hz... if I set timer1 to 65000, it decreases the 26Hz to 20Hz ... I didnt get iT! It should read the table faster, shoul'nt it?

I'm guessing here, wild stab, since I don't see any other code here...
It might be reading it faster, but it might be missing/skipping a Tmr1 interrupt due to how long it takes to accomplish your interrupt code.
Try increasing the number by small amounts, see if it actually increases up to a point, and then drops off.