Gremlins

[Germax]

If your bike starts to randomly die, lurches back and forward, RPM needle is spinning like compass in Bermuda triangle and you generally think that engine is about to explode while lights dim in and out you might want to check your battery terminals screws...

Just saying

 

[Gryphon]

Battery terminal screws?
Yes. Important safety tip...
Also (on older bikes) the ground is often rotten; make sure you have a good ground if your bike sometimes behaves 'haunted'.

 

[el_felo]

common issue on my old bike, replaced the screws with zip-ties and problem solved, somewhat!

 

[Germax]

That was old ninja 250 my GF got. Not sure if this is common but I know I'll check those terminals periodically.