Throttle throat

Original 7,50 mm diameter carburetor throat on OS 55 AX motor is not enough if YS fuel pressurized operating condition, so it was replaced into another one that has 9,0 mm throat for OS 46 AX with pomp system. The diameter of the throttle body to adopt onto the intake ports are the same each other, 13,50 mm.
The amount of intake air flow is dictated only by the capability of the motor itself under no relation of the suction pressure that has much to do with the stability at the highest operation.
This is the biggest advantage for the motor with fuel pressurized system, middle speed is controlled by YS Regulator and the lowest is done by the narrow down squeezing construction of the secondary needle as a upholstery moving according to lateral movement of a carburetor throttle barrel, of course the position of the needle is adjustable. This story is about the original carburetor but the 46 pump carb. has slit closing construction and the closest position is adjusted by out barrel rotation connected with a small eccentric adjusting screw, no barrel lateral movement occurs. Also, slow position stop limiter is prepared on the latter one, it's my indispensable requirement for a pressurized carburetor.
Now next step to invite YS Regulator system is setting a pressure nipple at the adequate position where the pressure signal could be drawn out, signal timing is very important to operate the system.