You're going to need a voltmeter and a manual. Here's a link to a manual but the quality of the pictures is low:
https://www.manualslib.com/manual/11...999-Sv650.html
Loss of spark on a curvy is often caused by a defective ignitor (aka ignition control unit) which is located in the tail but a bad plug/socket connector could also do it especially if the bikes been in a wet climate. There's a couple of voltages you can check - here's a schematic for the US curvy.
So with the ignition on you'll need to measure the dc voltage at the ignitor on the orange/white wire it should be 12V (battery voltage). Connect the voltmeter's black lead to battery negative.
The USA model has an anti-theft device so you'll also need to measure the voltage on the orange/red wire at the ignitor. Ideally this should be about 6v dc, but it may be lower.
Have you changed the ignition switch or fitted a different system?
You can also measure the voltage on the coils (orange/white) should be 12V dc. (ignition on). The coils are under the tank.
If you type in the following into your browser:
site: forums.sv650.org no spark
it will search this forum for this problem for further ideas.