I did spin it up with a drill and got only 1.7 volts ac going into the ignition coil.

65vac at the brown lead(source coil).
4vac at the red/white lead (pick up coil).
0vac at the black lead (pick up coil ground).

I’m going to go over all of the connectors with
contact cleaner tomorrow, because it should be done, with a bike this old.

Thanks for the feedback…

Ok, that's testing source & pulser individualy & also after the box leading to the plug coil & i've no idea what 'that' output should be after the box but guess a lot more than 1.7. But just to be doubly sure did you do a spin test with it all plugged in as normal & look for spark at the plug 'at a good spin' speed--& close the plug gap up to say 20thou & look in the dark. Source coils do give up with heat & vibration. Pulser coil on those are better than the early two stage type.

Just re-reading 65volts sounds a bit low & thought you had about 90. If 65 is spinning it with the drill then test again kick starting with plug in because it needs good voltage at the speed to fire. Same with pulser, but pulser only needs a few volts to do its job.

I'm running a simple system on one of my bikes [RT2] using only the source coil & a plug coil/box combined off an RG50. No pulser required & only one wire from source to plig coil. Anyway--don't let ne sidetrack you lol, i do weird things sometimes experimenting.

Thanks for the suggestion for cleaning the contacts. I went through the whole harness and throughly cleaned the contacts with cleaner. For 45 years of being plugged in, they weren’t to bad. But did take multiple swabbing to get the green residue to wash out on some of them.

Still no spark. But my 1.7 volts to the final ignition coil did go up to 3.2 volts, driven with a drill motor.

I have an email thing going with Rex’s Speed Shop, UK, they remanufacture source/charging coils. I’m thinking it may be a good idea to just to replace mine for preventative maintenance reasons alone.

Ok, so i gather still no spark at the plug via spinning with all hooked up. I remember the first problem we had at work when cdi arrived & was on an mx250 in "74 with no spark. Was a new bike & only been around the track a few time then no spark. Being a cdi novice & not knowing where to start, i must've got a sniff of a loose fitting multiplug because i fitted individual connectors to the wires to the box from stator & away it went. Only mentioning that because you said green stuff--corrosion so maybe crimp new connectors. But in your case you are getting readings so isn't a 'no contact' issue.

I’m back after it. I removed the flywheel, everything looks clean. I cleaned all the electrical mating parts with contact cleaner. The coil frames had a slight bit of residue. Two of the four magneto magnet metal faces had some slight varnish/rust residue, which I cleaned off.

I tested the charge coil, reading 166 ohms, which in spec. The local yamaha dealer was able find it for me, he also lent me the flywheel puller tool to.

The pulser coil reads 3.4 ohms and the lighting coil reads .3 ohms. If I can find out what the normal reading for these are I can determine if the pulser coil is good or not.

I checked the CDI for any short between the color wires and the ground, which were all good. 

I also removed an apple air tag that I had placed somewhat near the cdi, because you never know about electronics, maybe the tag is giving off some interference. 

 

End Notes, 3.16.2023

I ended up buying a Yamaha original pulser coil (ebay), a source coil and cdi module (Rex’s Speed Shop).  After I had all the parts in hand, I reasoned that the pulser, source and ignition coils were all reading within spec. for resistances and had to think that the cdi module was dead.

Rather than changing out any of the coils, it was easier just to swap out the cdi. I tested for spark and the juice was flowing, starting up on the second kick. 

I’m going to hang on to two coils I bought, just in case I need them.

A special note of gratitude to Rex’s for suppling the parts for the dt400 and many other old motorcyles.