I've been trying to get my basket case RT2 running before AMA vintage days next week. It started out with no spark. The points were in bad shape, so I ordered new ones. Still no spark after setting the gap. Long story short, I've replaced the:
points  K&S 08-0017
Condenser, and wiring out to points.
Ignition Coil
plug cap NGK LZFH
plug NGK BR8ES.
Spark was non-existant. On a whim, I replaced the plug with a BP7ES and grounded it against the case, and I have a spark, but it's still pretty weak. My understanding is that with the LZFH I should be running a resistor plug.

The source coil has 1.8ohms across it, and the same to ground. 
the points have about .4ohms when closed and .7ohms when open, from the black wire to ground.
This video is the spark when I have no resistor plug and cap.
The only wiring on the bike is black wire to ignition coil, and then a ground wire from the ignition coil frame back to the engine.
Any ideas on what else to check? 
 
I'm still getting everything else bolted onto the bike, so I haven't checked if this spark is good enough to run the bike or not.

With meter on points (black) wire and ignition coil disconnected, you should have 0 ohms with points closed and pretty close to the 1.8 ohms of the source coil with points open.

Since you don't have 0, clean the point contacts.

Digital meters can suck at this... and keep in mind these old magnetos don't throw a bolt of lightning across the room at cranking speeds. Spark never looks super strong.

I sanded the new points before I installed them, ran some cardstock through them to clean them up too. Before installing them they check at 0hms close and infinity when open. The 0.4 ohms resistance is coming through the wiring somewhere. I get that measurement when I'm checking between the black ignition wire at the coil and ground.

Any idea why the resistance might be so low (0.7ohms instead of 1.8ohms) with the points opened? I guess I could disconnect the wire from the points and see if the problem is before the points or after.

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Don't take too much notice of me, but if its connected to the plug coil does 'that' coil primary resistance come into the numbers. Or is it when points are shut zero is always zero regardless.
Ok--rethink--think i mean when open does secondary coil primary add to the number. Not that it matters i guess, contact zero then no contact resistance reading.
Never mind.

I disconnected the bullet terminal to take those measurements. In my picture, it kinda looks like the points wire is touching the condenser frame. I'll check that tonight. It wouldn't give me the .4 ohms closed, but it might explain the reduced measurement with open points.
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OK, the points wire was grounding out on the condenser frame. 
I have it all set up with 0o ms resistance closed, and 2.9ohms open, from the meter, the points are open at -2.51mm. I had to bring the gap down a bit to for the new points to open at -2.5mm, with the points gapped to 0.015" they wanted to open at about 3.2mm BTDC.
There's a weak spark. Tonight once I get some gas I'll see if that's enough for it to run.
 

I got the bike all gassed up. It's missing some of the Autolube lines, so I filled it with pre-mix at 32:1. The previous owner said he put in new crank and piston, but the piston at least didn't look new when I had the head off for timing.
Anyway, I hooked up the gas and tried to start the bike, and nothing. It didn't even try to start. I've got a friend dropping off a compression tester, but I'm not sure what else to look at.
the decomp lever feels loose/not right, but it should have the decomp on to start anyway, right?

​​​​​I opened up the carb and everything is clean in there, blew some compressed air through it to make sure.
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bit of a guessing game on my part.
But if the carb & Choke Jet in the bowl are clean, then open the choke & leave the throttle fully closed as choke won't work very well if at all on an open throttle.
If it doesn't fire after kicking it till ya leg drops off, check there's fuel in the bowl by pulling the side mounted main jet. Maybe check that before anything else.
If no fuel see if you've mistakenly fitted the separate float upside down as is very easy to do with the individual floats.
But if the plug is getting wet, then i doubt any of the above apply.
Be sure the throttle is moving freely up & all the way down too, & back the speed screw out to be sure it's bottoming then take it up one turn from touching the slide, maybe half a turn. Can feel that by finger on the screw & feel the clunk onto the screw from the slide.

Thanks for this- I spent some time with the carb yesterday. The float jet was a little dirty so it was leaking. I took care of that, and cleaned the main and pilot jet. Not sure how to clean out the choke circuit, other than blowing air in there. The bike still wouldn't start, so I checked compression, getting about 90psi, which I think is too low. I previously had the head off to set timing, so I took it off again to anneal the copper gasket. I found...​​​​
Some scoring on the cylinder.

Decomp wasn't sealing. It wouldn't retract all the way. I cleaned it, and it's a bit better, but I don't trust it. It was also missing the gasket, so I put a copper one on. 
Is there an easy plug to put in there? I'd like to take it out for now just to eliminate it as a source of problems.

Pulled the cylinder to check rings, they were moving around ok, but the top one wasn't located on the detent. I put it back, and annealed the head gasket and..... didn't feel any different. My friend with the gauges was gone, but I don't think there was any improvement.

Also what do the numbers on the piston mean? Exhaust side had a 74, intake said 80.25.
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80.25 just means its on first oversize.
Should still start with 90psi even if its a bit low. If the cylinder was 100% & decomp valve was operated, the comp would likely be lower than 90 for easy starting--i'm guessing--so with it closed & getting 90 she should light up--i think.
My "70 RT1 motor i once had, was so worn that it had very very low comp to feel--but still started with a good kick.