1976 DT400 Ohm tested the pulser 90ohms, charge coil 120 ohms, tested the ignition coil at around 2ohm primary and 18k ohms secondary. The ignition coil numbers seem high but I am using an analog meter to test with. And using the D battery testing method on the coil makes nice fat sparks on the spark plug as detailed in this thread yamaha-enduros.com/index.php/forums/how-...a-no-spark-condition

So my thought is the CDI box is bad but the high secondary coil reading makes me wonder about it too since is supposed to be 0.6 and 6k ohms but again it makes spark with the D battery tester. Anyone else get high ignition coil readings on a good working coil?

Forgot to mention that kill and ignition switch es test as good and thoroughly cleaned all wire contacts.

Be intersting to know the ac voltage from the charge coil brown--& the pulse for that matter. I'm guessing a bit but something like 80 volts kicking from the brown. Maybe 5 to 10 or so from white/red & white/green. But not sure if you'd earth one color & test the other with meter negative to earth--or run one color to pos & one to neg. I use a peak meter so would read double. Bad connections of any of the wires or bad crimping will stop it. Often it can be the most simple thing but sure isn't simple to find thats for sure.

Thanks for  the reply. I did try using my analog meter on the charge and pulse connections and they both cause the needle to deflect/register voltage but the needle moves too much to get an accurate reading. I think I just connected the meter the same as the ohm test.

I do have a better digital meter that runs on 9v battery but I was worried that the 9v power could hurt the 6 volt system somehow?

Think I may take a chance and buy a used cdi off Ebay and hope I get lucky. Wish I could test my existing cdi unit.

"Wish I could test my existing cdi unit."

I'm reluctant to put words into his mouth, but DEET from this forum (This email address is being protected from spambots. You need JavaScript enabled to view it.) might he able to provide this service for you. He is in the US.

I'm not into digital stuff [too old lol] like to see that needle swing. You'll need your meter set on AC volts & a setting higher than what you expect to get kicking it over with plug out to make it easier. But ideally you need a good voltage kicking through compression as that's the rpm you'll be hoping it'll start at. But anyway, have plug out & spin it initially to get an idea. That's mag loom still unhooked from up top & testing the brown. CDI boxes are pretty reliable, but then again close to 50 years old so could be right.
"Not recommending my dodgy ideas for you" but i have my RT2 motor using a DT360A mag running the source coil only wired direct to an Suzy RG50 style secondary coil cdi box combined. No pulser coil.

I did another round of testing.this time I got 90ohm from the CDI charge coil and 90ohm on the pulser. Set the meter to AC and the 50v range because I was only seeing about 10 - 14V between the brown wire and engine ground on charge coil - kicking as hard as I could. Guess it looks like the cdi charge coil is junk?

Hi All
My name is Rick and I new to this site.
      I have a 75 DT400 with about same problem and my question is about the ac Source 2 coil part# 445-85512-20-00. The "Yamaha DT250/400 Service Manual" has the specs of this coil at 12.5 +/- 10% ohms. My bike coil has a ohm reading of 96.6 now. So I bought a pricey "New-Old Stock" coil from Ebay that came with a reading of 131.6 ohms. I also found a U.K. Company that sells a new replica of the same coil (same part# 445-85512-20-00) that has a advertised 130 ohm spec. I email them "Why the different ohm values? Is this a U.K. version for bikes that were sold in the U.K?" They basically replied that 130 ohms was the value of there coil.
     Anyways what is the real normal ohms reading of this coil? 12.5, 130, or 125???
                                                           Thanks in advance for any advice or ideas. PS I used a Ideal 61-737 for testing and all other coils are within specs.

The factory manual has errors in it from what I understand. I believe it is supposed to be 120 ohm +/- 10%. It shows different specs in separate areas of the manual. The scan I attached should be correct.

Hey Buggin
             Thank you, Thank you for the quick reply. I hate elusive electrical problems especially when the dealer shop manual is inaccurate after 6th printing. Now I  know It MIGHT? be worth it to replace the old coil with the pricey new/old 131.6 ohm already +5% out of spec going the wrong way coil. I'll post what happens next.
THANKS AGAIN you saved me a lot of time and hopefully some money.
rick