Welcome...these bikes don't have much low end torque. All the power is at the top of the tach. Try riding at higher rpms. I am not very familiar with the 650, but the 550, which is very similar mechanically really does not make decent power until at least 4500 rpm. False neutrals are not caused by the clutch. Try to be very deliberate when you shift these, many like to put a little gentle pressure on the shifter ahead of time, then when the clutch is pulled, clunk the shifter home firmly. False neutrals can also be caused by transmission problems such as bent shift forks or worn out gear dogs.