Timing's not going to make it run & stop randomly. Anywhere from 2+ to 3- & she'll keep running well. Spark can look weak but depends on if ya looking in the shed or outside. I guess plug coils been tried--i best go read back. Stator coil is a possibility but if Deet's been there then highly unlikely unless damaged while fitting the stator or flywheel back on. Short cut the black straight to the plug coil & if there's a short black with a female covered plug coming off that out of the mag loom just be sure it can't touch earth--shouldn't be able to though.. Talking carb. Even if it was blocked pretty bad the choke 'if clear' would keep it running to a point. If ya not sure about the carb just have a 14 T bar handy to whip the main jet out the side when motor stops to see if the bowl has fuel in it. Crank key ok--i guess it must be if it runs. The way you described it by memory was it 'just cuts of' instant, which sure sounds electrical. But--could try grabbing the choke & close the throttle to see if it catches on again if still has fuel in the bowl. I'm rambling --.

I have the black wire going from the mag to the coil. As a matter of fact i made my own kill switch and have determined many times that isnt the issue, that works just fine but i have disconnected that in the past just to eliminate that possibility. No damage to the flywheel or stator while re-assembling. From what i can tell its not starving for gas, the handful of times ive had this bike going she will get up and go its just a matter of time before she dies. I know fuel is getting to the petcock and to the carb for sure.
I plan to take the carb off tomorrow and get back on here. The more i think on it the more i believe it is the carb. If i have the points at 15 and put a new plug in her she fires up and goes, after X amount of time she will die and then im back to square one which is weak spark or no spark until i put a new plug in it. I always check on the points when this happens and there still at 15. So if you ask me that plug is fouling even though it really doesnt look fouled but again i need to get more then 5-10 mins of ride time on this thing. I need to see if the jets are stock then go from there.

Cleaning the carb many times doesn't stack up. Clean it once. Just let it flow out the main jet bung but i know it makes a me. If constant after a minute the is ok in the flow. Only other carb thing is if the floats ares set so almost no fuel is present then--maybe a cause. One more thing is any breathers into the carb body or bowl must be free, or at least one to let air in & i did have that once on my kids yz80 where the breather pipes hung down in the mud & got plugged so on open throttle it just ran out of gas. Took a bit of head scratching until i rode it to sample it then go looking. But fuel problems like that give a hint of fading out before stopping. Which is why i still feel yours is ignition related--guessing.

I keep thinking the same thing, ignition but dont know what else it could be, ive gone through everything. Ive tried 3 different coils and it always ends the same. I guess i can try the coil off my 74 DT250 because i know for a fact that one is good. The other 3 are used but im confident their fine, its something else. Im still going to go into that carb first, i can throw up some pictures, test the floats again and go from there i guess.

So i finally got her going and was able to burn a tank of gas in her however my issue still isnt solved but im quite certain its the carb. Using the newest plug i got which is the same used plug from yesterday i was able to get her going. i first checked spark and it was weak and to the point where you couldnt see it so i decided to wire brush the plug even though it didnt look dirty and check the spark and sure enough it was blue and you could hear it.
I shot a little gas into the back of the carb for a quick start and sure enough she fired up then died. so again i checked spark and it had nothing, i then wire brushed the plug and sure enough i had good looking and sounding spark. I went to fire her up again but this time i left the gas off on the pet cock and took off the moment she fired up.
At first she was sputtering and farting like the plug was fouled or almost as if it was missing but after it burned up pretty much all the gas in the carb i was able to turn the gas on while riding in 1st/2nd gear to make her come out of it. Once it came out of it i was able to rip like a mad man but i still am having issues getting it to idle. I think whats going on is the jets are too big, float height might be off, possibly needle height or something isnt quite sealed right in the carb. The guy i got it from used to ice race with it so i suspect its been jetted out but i cant say for sure. I am uploading some pics that hopefully will help get to the bottom of this thing.
 
 
 
 
 

I should note that the little black O ring that seals in the bowl is not one from Yamaha but an O ring that i had in my box that fits around it and fits pretty snug into the bowl. That so called "jet" it wraps around does not have any numbers on it from what i can see and i feel that it should. I tested the floats to make sure they were working properly which they are. Heres a few more pics that hopefully help.
 
 
 
 

Pic of the carb upsidedown shows the fuel level would be too high with the float arm at that angle & parallel is about right. Also just wondering if you have a thick brass washer under the Oring fitting as looks like none there in which case the Oring may struggle to fit down in the bowl. Oring 'does' look quite fat or sitting out more than usual. I know ya not using genuine & i do the same--whatever works. I guess you just sat the fitting there like that to show us. Does just sound like its just sooting up the plug & shorting it to earth. Once baked on its hard to clean off. Plug sand blaster at work got lots of use back in those days. Straight oil won't short it but its when it gets baked & black & of course the colder the pug the easier it'll get shorted. Just put a hot car plug in & go for a ride, not a mad extended full song ride but give it a rev up & down to clear it--if it 'will' clear. With the Oring fitting can you use a needle jet with it screwed into as an extension to poke it down in the bowl cavity to be sure it'll compress down there without folding up to leak or escape. I'll mention the thick brass washer again so you can tell me its there on the bench.

Lets do some baby steps here lol for starters when i took the pics everything was loose for pic purposes. As for the Brass washer i believe its in there but it didnt fall out this time when i took the carb apart ill have to check on that. The O ring im positive is sealing in the bowl because it was so tight i had to gently clamp the carb in a vice and use a piece of wood and a hammer to gently tap the bowl off lol.
As for the float height is it currently set too rich?
Also i forgot to mention the number for that needle that goes in the slide with the E clip reads 6f16. Oh and i didnt get a picture of what i beleive is the pilot jet. The one you need a tiny screw driver to get out.

RT325 has a good eye...  he spotted several important things that should be addressed. 

I second the items RT325 pointed out and I’ll go one further in that air filter is not helping you either.