Hi,
Sure hoping someone can give me some help/answers.. I am working on my '75 DT 250 B, It had been
running fine, then one day, no start, no spark. I pulled the flywheel and one of the screws that held the lighting
coil had back out and screwed up the windings. They seem to be as rare as rocking
horse poop and expensive. It has sat for a couple of years and I finally did some searching on the 'bay. The
parts list I have from a dealer they printed out showed three parts numbers for the lighting coil.
One is 450-81313-20-00, with 438-81313-2 in parenthesis behind it. The other is 498-81313-21-00 (why three
numbers are listed, I don't know)... I found part # 1M181313-21-00, and duh, impetuously bought it..
from the research I did, it is for a '77 250. The wiring colors from the loom that connect to the coil are: red/green, yellow, and green. Colors from the one I bought are green, yellow and black. It does bolt in
but the circumference of the windings are slightly smaller. My question is will this one be usable, and
if so any thoughts on the wiring connections ? The diagram appears to show the wires go to the
switch. Will there be enough voltage difference to screw something up ? or not light up as it should ?
I've been riding a long time, as I'm an old guy, and I sure would like to get it up and running. Can't
tell You how much I appreciate any help and Your time in advance.

Thanks
Dave

Partzilla doesn't show a "75 250 so going by a "76 compared to a "77 it looks like the ignition source coil earths into the lighting coil. I know that ignition on points models is black from the source up to the loom & ending at the plug coil via loom & switch. I'm wondering if you have a black from the lighting if it's meant join the earth end of the source coil. Only thing is that then won't leave 3 lighting wires up to the loom. Black won't be lighting though, no matter what!!. Think you said it ran outa spark though. So is the source coil poohed? or is it not sparking due to lighting coil damage & the fact that the source coil earths via that?. If that's the case & the sorcy thing is undamaged you could get it sparking by simply earthing 'that' earth wire from the source coil direct to the coil post--or might even have a tag on the coil post to solder the earth wire too--& that'll get ya running at least. Cheers from NZ where we do all sorts of dodgy s$%t [& i'm old too [73]. Worked in a yamaha workshop during all those fun times which really only means i was ok at finding a way around a problem on a good day, but not actually fixing it as too expensive for parts in those days. Sorry if no help in the end.

www.partzilla.com/catalog/yamaha/motorcy...wheel-magneto-dt250d

www.partzilla.com/catalog/yamaha/motorcy...wheel-magneto-250b-c

Thank You RT325, some things to consider for sure. I really appreciate the time You took.

Dave