So I have a low mileage nice dt250 I am restoring. I had it running and tuned perfectly with all lights working, and battery charging perfectly. The timing was set perfect to factory settings and the points were clean and gapped on spec.   I parked it in a barn for 3 weeks. When we got it back out. It is absolutely dead spark. The battery side works fine (horn, tail and brake lights). I investigated the main key switch, kill switch, and ignition coil, wire, and spark plug. All check out perfect. When I investigated the kill wire itself though, I have found even when I have the switches unplugged, it reads and having continuity to ground. I have no idea how this is possible or what would cause this. Any help would be appreciated. I have no idea where to check next. Any advice on how to bypass the kill wire to test for an unwanted ground is the only thing I can think of. 
 

"Continuity to ground" that you're describing is probably normal. It's a magneto. With points open resistance is only between 1 and 2 ohms. A "continuity tester" will normally show that as "continuity".

My suggestion is to clean the point contacts

Second Mark on cleaning points. Picked up a running 75 DT250 last Nov. that had lighting issues. Worked on it to get lights working and also had wrong kill switch (backwards). Got everything work including kill switch and had great spark when put it in garage for winter. Being a couple mile from ocean in New England a lot of temp. changes. Pulled it out in the spring and no spark. Went thru wiring and kill switch and all fine. Getting ready to pull flywheel and decided to clean point with brake cleaner and old style business card (not glossy one) pulled thru. Worked like a charm and have had no problems since.
 Also picked up a CT2 that was told had no spark and P O had put new points in and gave up. Again brake cleaner and business card fixed it.
 As for timing I took Mark's suggestion on getting a Buzz Box and so easy to time them now.
Thanks Mark!

Thanks to Mark T! I was not aware of that about the continuity to ground test. I assumed it would read open. Ok. I will definitely try to clean the points first thing. I had assumed that they would be good to go but assuming is usually a bad move. I usually always recommend "check the points first". Time to follow my own advice. I will post results either way.
 

 

Now the forum works as well as this ignition. Anyway cant post a photo. What's new. 

As expected, cleaned the points, no change. Dead as a hammer. Any idea how to totally isolate the kill wire system from the ignition?

I can't sort out this ignition. It is unlike any real ignition I have ever seen. There is separate kill wire.

Run black wire from the mag loom direct to the plug coil, that eliminates everything else. Just be sure the throttle is shutting off fully.

Well, I replaced the points and condenser, reset the timing, amd it runs like a top. It blows my mind. It must have been the condenser I guess? I cleaned the points very well with sandpaper and tested them....IDK. anyway. I have an very fat, beautiful spark now and it runs great. I guess I will never assume anything with points again and just replace them at the first sign of trouble every time. I wasted a ton of time because I couldn't convince myself it was them. Thanks for the help to all who replied.

Glad you got it sorted buddy & one thing I’d like to add here  as points cleaning was talked about , a long time two stroke mechanic once told me to use a (USA) dollar bill folded up to clean point surfaces after fine grit sandpaper. Something special about the cloth fibers in money???   The dollar has worked better for me although using a business card is by far the more popular method

Congrats. Many of us have been there before. I know I have.