Hi folks, my 2015 tracer is intermittently not starting. Turns on, fuel pump whirrs, push start button - nothing. Sometimes if I keep the button pushed it will start. Other times I need to turn off and on the ignition. When it does start it fires up perfectly. When it doesnt start I can hear a click under the saddle.

Any ideas?

99% this is your battery, even a "charged" battery can have low voltage/voltage drop depending on age and the load it had during its lifetime.

Before you rip apart the bike or do anything expensive: check your battery terminals to see if they're loose or corroded, test the battery, charge the battery, replace the battery. 

Ill stick a battery in it and see what happans. Thanks

I agree with @jthayer09  If your 2015 still has the original battery its pushing 10 years soon.

And when you replace the battery, CHECK THE POLARITY OF THE TERMINALS, this battery actually lays on its side and more than a few have put the battery in backwards connecting to the wrong terminals.

If you prove that it's not the battery or battery related, it may be that the starter relay is failing.  Ask me how I know. 🙂

I was having exactly those symptoms that you describe on my 2015 bike.

22 minutes ago, dazzler24 said:

If you prove that it's not the battery or battery related, it may be that the starter relay is failing.  Ask me how I know. 🙂

I was having exactly those symptoms that you describe on my 2015 bike.

I think you could be right. The bike starts really easily when it does start. Relay is cheaper than a battery too

1 hour ago, Geezer1000 said:

I think you could be right. The bike starts really easily when it does start. Relay is cheaper than a battery too

You could always try bridging (carefully) the relay when it's being cantankerous, and even when it's not, to prove if your getting a positive crank every time.  Might have to repeat the exercise to ensure that's where your problem is located.

You should be able to leave the kill switch off to do the testing so the bike doesn't start every time you try it.

Don't rule out your battery though until you've satisfied the testing above is repeatable and reliable.

Intermittent faults can lead you down false rabbit holes, as I have learnt.

Good luck.