- this is a tic of mine - i love rephased motors...yes this is changing the crank set up so the pistons dont travel together...the advantage is that you dont lose energy when both pistons are at TDC as 1 piston is always mid stroke when the other is TDC..ie rephase-when one piston is not moving (TDC) the other is at max velocity (mid stroke)...removes the search for energy to overcome inertia when both pistons are stopped together (non-rephased TDC)
- so there is a power saving
- this leads also to less vibration as the motor runs smoother
- better responsiveness
- slightly torquier
- if you do this weld the pins to the flywheels...balancing helps too
- there are 2 ways of doing this
- split the crank in the middle-rotate the right hand side 3 splines and press back together...277 rephase
- split the crank, replace the 2nd flywheel from the right with a slightly modified 3rd flywheel (remove 21mm from the pin boss where the cam sprocket seats), use a 270° pin and press together 90° out of phase...270 rephase
- both of these processes require a suitably modified camshaft and a cam-driven ignition system...a good time to consider installing a permanant magnet alternator and dual lobe points cam
- in my opinion yamaha missed a golden opportunity to produce a truly extraordinary motor by turning this idea down...i have done this and highly recommend this to anyone interested in spending the effort...virtually all modern-day parallel twins are built this way