What are the difference of samurai ( Is the 4 "balancers") and the swift ( Is the 8 "balancers") crankshaft? ( Really i dont know how is named, i think is the "balancers" so if any one can teach me, thanks)
The answer to your question will depend on "which" Samurai and "which" Swift - there are actually significant differences between different years/models - for the Samurai there were two different 1.3 motors, and at least three in the case of the Swift, and I'm only looking at the 1.3s for the Swift.
The Samurai could have either 1298cc or 1324 cc motors and the crankshaft stroke is what is different between the two.
The Swift 1.3 motors were all 1298cc, and there are at least two different crankshafts - the four "counterweight" hollow cast crank used in the SOHC motors and the eight "counterweight" forged crank used in the DOHC motor.
The cast crankshaft used in the SOHC Swift motor is the same crankshaft used in the 1298cc Samurai, and is physically interchangeable with the forged crankshaft used in the DOHC Swift, althout the forged crank is stronger and better balanced.
From a perfomance standpoint, the forged crank would be best, because of the better balance and greater strength, but it will not provide any performance increases on it's own, it will simply allow you to build a stronger motor.