Dumb question about spark

[callbr549]

I'm not totally sure how to check if I'm getting spark. I've read that I remove a plug and then hold it against the engine.  Does that mean the threaded part of the plug, or the contact that is in the center where the gap is? And when I'm holding it like that, do I try starting the bike? So with one hand I'm holding the spark plug and the other I'm holding the starter button?

My bike was running rough at low rpm, I replaced spark plugs that I happened to have on hand and then decided I would try checking timing, points etc. I bought an inductive timing light at the parts store, set it up to check timing on 1 or 4 (another question -- are they numbered left to right while sitting on the bike?) and thought the timing light wasn't working. Moved it over to 2 (or 3?) timing light works fine, which makes me think no current is going to 1 and 4? (light doesn't work on either of the outside cylinders). Thought I should check spark visually to confirm,  if you can help figure out how to do it. Thanks.

[Hellbilly429]

Pull out one plug at a time, keep it connected to the spark plug wire and contact the bottom of the plug to the side of the engine, then hit the starter, you should be able to see the sparks. if you are to do it this way tho, be careful and wear rubber gloves if you can so you don't get electricuted. Easiest way to do it would be to take one of your old plugs (if they still work) and just pull off one of the wires and pop on the old plug to the wire and check for spark that way.
And yes, they are numbered left to right 1-4 while you are sitting on the bike.
And cylinders 1 and 4 are on the same coil and fire at the same time, so if 1 isn't working than the other one probably isn't either.