Nope, you need to confirm starter-solenoid is actually bad before replacing it. You'd be replacing a perfectly-working part with brand-new perfectly-working part and nothing will change. Your bike
still wont' start because you haven't
tested, measured and confirmed failed parts. Measure for +12v on yellow/red activation line going into solenoid when you push start-button.
1. IF there's power on that line AND relay doesn't click & power starter, THEN starter-relay is bad... however
2. IF there's NO power on starter-solenoid activation line, then you can't conclude that solenoid is bad. You've got switch-problem somewhere with series of switches starting from ignition-switch.
https://www.ninjette.org/forums/showthread.php?t=312718
DID YOU MEASURE the kickstand switch and neutral switches? What resistance values did you get? Do the following tests and get
numbers.
1. resistance between kickstand-switch connector terminals with kickstand UP and DOWN. What's the numbers?
2. resistance between neutral-switch and chassis-ground with bike in gear and in NEUTRAL. What's the resistance numbers?
3. resistance between clutch-switch connector terminals with clutch-lever OUT and SQUEEZED-IN. What's the numbers?