const int MPU_addr=0x68; // I2C address of the MPU-6050
Addresses are bytes. Get out of the habit of wasting memory.
AcX=Wire.read()<<8|Wire.read(); // 0x3B (ACCEL_XOUT_H) & 0x3C (ACCEL_XOUT_L)
AcY=Wire.read()<<8|Wire.read(); // 0x3D (ACCEL_YOUT_H) & 0x3E (ACCEL_YOUT_L)
AcZ=Wire.read()<<8|Wire.read();
Wire.read() returns a byte. What happens to a byte when you shift it 8 bits to the left?