My Emgo coil, part number I gave earlier, measures 0.8 primary and 6250 secondary

Sounds like keeping warm is a priority at the moment--so keep warm. Too hot here in NZ, can't win.

Thank you Mark, that's helpful.  I see them for sale on EBay  for as low as $12 including shipping.   I'll probably wait until after I do my next test though, given that I'd have to fabricate a mounting bracket.  I also dug through my spare parts bin and found a spare TY250 coil with the same mounting as the DT3; it tests at .9 and 6500, so its worthy of trying out. 

New Zealand, eh?    Your country breeds fine racecar drivers; I'm thinking of the two Scotts, Dixon and McGlaughlin who I watch in the Indycar series.

Here is a photo of what we've got here in New York, looking out at my driveway a couple days ago.  But it will change soon.

 

If you buy on ebay I'd buy from a legit brick and mortar parts house selling there.  Too many counterfeits of just about anything out there.  Emgo comes in a box. not loose. 

So, I promised to expand this thread from "Testing the Ignition Coil" to addressing the larger issue, the poor running condition of this bike since I got it last year.   I had been waiting for the snow to melt here in Syracuse to do some road testing.    Well,  that happened last week, and I managed to get it running very well !    Thank you to MarkT, RT325 and 1971DT250 and others for your assistance.

In brief, here is what happened.  The bike would start fine, but would gurgle and stall at low RPMs. It would clear out in the higher revs, and once it "ran away" at high rpms, and I had to pull out the plug to stop the engine. This got me thinking about the crank seals.  There were no intake leaks, nor at the base gasket.  I had rebuilt the carb.

Testing was hampered by a major leak at the float bowl. I got a new float bowl gasket, but this didn't fix the stream of gas leaking from the mating surface.  Pulled the carb again, and under inspection I saw that the bowl contact surface on one side was significantly warped.  I knew to check this out cuz I've heard of Mikuni BS38's warping like this when the owner cranked down too hard on the screws.   There were two NOS float bowls on EBay for $100 each, but they both looked sketchy. So I decided to fix my bowl with JB Weld.  24 hours later, the carb was back together, and the leak was sealed.  In order to track the epoxy's response to long-term contact with gas (non-ethanol premium), I set up an "total emersion" experiment, a glob of  "set", hardened JB Weld placed in a jar of gas which I can check from time to time. Continued testing on the road showed small increments of clearer running, with exhaust smoke slowly reducing to "normal".  The plug was oil-fouling, but this improved.  Eventually, the bike ran clear and idled nicely, and the plug looked good. No further run-away. Good power.  I was happy.  

I'm thinking that perhaps when the bike sat for a long time before I bought it, injection oil made its way into the cylinder from the pump and built up.   Or, perhaps the right side crank seal was leaking oil (and air) , but once I got it running a good deal, the seal recovered, and sealed back up.   The real main seal on my Mazda Miata does this every spring; it leaks for the first few days of running, then seals itself up.

 I bought crank seals anyway; this will make a good winter project this coming
December.

Dude. 



 

 ..

Congratulations! Nice work. 

Nice work and good write up!