Hi folks,

This is for my 78 DT250 with around 9000 miles.

Long story short, breaker point contact surfaces looked dirty, sanded them with sand paper, cleaned with rubbing alcohol and no longer have "good" spark. Under closer look at the surfaces with jeweler's glasses, I noticed bad pitting and I probably took away material on the top contact surface with sanding, causing my no spark situation. Imgur pic links at the bottom.

So I finally got around to doing the crank seals and have started with the magneto side first. Took everything off, got the old seal out and the new one in and reassembled everything. Went very well and took my time in doing so.

So it's time, let's see how this DT runs without sucking air in through that seal! Kicking it over a few times and nothing. Gas on, ignition turned on, Choke on, and not even a stumble. Eventually the plug was soaked after several attempts. I had issues with this before with hard starts with minorly fouled plugs so I grabbed a new plug but unlike prior new plugs, it did not zing to life on that first kick.

So not sure what's up, I decided to try and bump start. First gear attempt had the rear wheel completely locked up upon the letting the clutch lever out. Tried the same in second gear, still locked the rear tire up but it did start to turn over but with no spark at all. Same for a 3rd gear bump start attempt. No signs of spark.

Thinking what has changed now. I figured that when I had unhooked the magneto wiring harness that I may have cracked a wire as some of the factory loom was very hard and brittle and did crack in two places. So I removed the loom only to find the wires to be in great shape still. So I put the flywheel back on and then continued to test. 

I did see a few sparks on the plug this time but not nearly as strong as what I saw when I first go the bike and was doing initial spot checks. 

Thinking again, what else could cause a seemingly fine running bike before to having little to no spark at all? That is when I realized doing the good deed of cleaning the points might have inadvertently caused my new no spark issue. I noticed that the contact surface yesterday looked a little discolored so as I've done with other bikes with points, I took some sandpaper in between them, blew any bits off with compressed air and wiped them with rubbing alcohol until their was no more residue. To the naked eye, they looked good.

Then, I got my jewelers glasses and and took a closer look. Here's what I ended up seeing (and the overall plate/wiring harness inspection)

Pitted contact surface:


stator plate:


stator plate plus wiring harness


 

Oh, I can't add imgur links? How do others? Feel free to search for me if you want, my username is (and this starts with a five and not the letter "S") 5omeUser