Pull the air box and throttle body so you can actually see the injectors spray. I would not recommend just pulling the injectors out and testing as they can pop out and you will have fuel spraying every where. Not that I have ever turned a motor over with the injector out and had gas all over me, the quad, and the floor while trying to scramble to disconnect the fuse and wondering if the spark from that would be enough to end my life. I also recommend a fire extinguisher in the garage.
Yeah, I don't play without a fire extinguisher nearby, but I also didn't test the injectors while they were attached. I removed them completely and used a battery and test leads I had on the bench to test the injectors.
That's a good visual though! During T-day weekend we tried briefly to troubleshoot the fuel flow and I had one person with the fire extinguisher on stand-by. Picture the robot holding the fire extinguisher in "Iron Man", if you will.
A bit of a side note:
I removed the spark plug and used a flashlight to peer down into the plug hole. It appeared to be wet and I could tell there was some carbon build-up on the piston. Not sure if that means anything (except that fuel appears to be getting to the combustion chamber).