I am finishing up a restoration on a 1975 DT175. In the process I replaced all the bearings and seals in the engine. The carb was rebuilt with a Keyster rebuild kit. The points and condenser were replaced. The timing is set as close to 1.8mm BTDC as I can get it. It's probably around 1.5mm. Compression is 110 and I am getting a nice blue spark. I have scoured the forums and tried everything I can think of but I cannot get it started. The only time I can get it to fire is if I pour a little gas in the cylinder. This obviously points to the carb, but I have had the carb off several times and cannot find any problems with it. It was cleaned in an ultrasonic cleaner and all the orifaces are clear. I have read that it is better to use genuine Mikuni jets, but I would think that it would still fire with rebuild kit jets. One thing to not is that when I do get it to fire, a little bit of smoke comes from the magneto (I have the cover off because I have been adjusting the timing.) Does this mean the crank seals are bad? I replaced them during the rebuild, so I find that hard to believe. I have spent countless hours the last 3 weeks trying to figure this out and I'm at the end of my rope. Any help would be greatly appreciated.

youtube.com/shorts/DXAEBnu87bs?feature=share

There is a tiny jet in the float bowl that is used for cold starting - is this blocked or clear?

See the bottom left of the second image in the attached link.

BODY, FLOAT CHAMBER for DT175 1975 USA - order at CMSNL

Sorry to ask, but, Any possibility the crank key has been left out. I guess it must be ok if the timing is in the ball park but good to check its in one piece. Smoke from the mag 'does sound' like its pushed the seal out or wrong ID on the seal, or timing is so far out that it's firing down the transfers into the crankcase. I'm guessing by 1975 the flywheel did not have the advancer fitted. Carb is unlikely to be so bad that it wouldn't run at all regardless of type of rebuild kit. I have seen floats fitted upside-down stopping fuel flow though. Hope right side seal is good & correct size. Could get someone to help push starting it but be certain the throttle is shutting right off when you want it to. Ok i'm no help sorry but smoke from the mag sounds sus at best.

The tiny jet in the float bowl that is used for cold starting is clear.

The crank key is good. I double checked the float and it is correct and set at the 20mm height spec. I did not replace the piston rings when I had it all apart. Maybe I should have.  

Don't worry about piston & rings--unless its fitted back to front which i've seen before with reed holes to exhaust by mistake--. I can see in the video you have good compression kicking. One thing though is you have a short kick stroke & only 'just' getting through one compression. Is it possible to move the lever forward a spline or two, to get a better swing. By memory those models are not the best in the way it works for room when kicking over.
I should add again that "No Way" should smoke be coming from the magneto crank seal.

The kick lever is as far as it will go. You got me worried that I might have fitted the piston back to front, so I pulled off the carb and confirmed that the reed holes are facing the carb, not the exhaust.

Why can't you get timing to correct setting? Are you locking advance open when setting timing?

Are you holding throttle wide open when trying to start?

Yes, I am locking the advance open when setting the timing. When I go past 1.5mm BTDC trying to get to 1.8mm, the points stay open and I lose spark altogether. I wonder if the points that I bought are the problem. They are not OEM, but they were spec'ed for my bike and they looked just like the old ones. I am not holding the throttle wide open when trying to start, although I am slightly opening it.

Earlier i looked on partzilla & didn't show the advancer in "75, but ok you have one & holding it open!!. You're gonna hate me for this but you are going before tdc in the right direction? ie motor goes 'anti' clock sitting looking at the flywheel. Ignore that comment as thinking about it you'd need a hell of a gap to open before when turning clockwise--i think i think.