A microcontroller like an Arduino or ESP32 is needed for the following. The easiest way is to use an RPM sensor at the ignition wire (can be found on Google, see e.g. here. For speed logging, a reed sensor can be used and calculate the impulses per time. The microcontroller can log to an SDCard (adapter needed) or send the data with Bluetooth or wireless LAN to a laptop (ESP32 needed).
Another possibility is to use an OBD Bluetooth adapter with a laptop or microcontroller. I have done this for a BMW G 650 motorcycle, see here. For testing, connect the Bluetooth adapter to the diagnostic cable of the ECU (check wiring diagram). Then connect a PC to the Bluetooth adapter, get the virtual COM port in device manager and connect with PuTTY or another serial terminal emulator. Then, try the following commands:
AT L1 (for PuTTY, so cursor goes to next line after every answer, not needed on microcontroller)
AT AL (allow long messages)
AT SP 5 (sets protocol to KWP2000)
AT SH 81 12 F1 (set the header, 81 means physical addressing with length, 12 is the ECU address, F1 is the Bluetooth adapter address, F3 can also be tried instead
81 starts the communication
2108 request sensor data
You should now receive a byte string. The data positions can be found here.
More information can be found in the ELM327DS, KWP2000 ISO 14230-2 and KWP2000 ISO 14230-3 documents. For the Suzuki implementation this library is interesting.