Hello all, I’m looking for guidance on how to test my charging coil on my 1974 DT 250 my question is can I test the coil off the bike or does it need to be on the bike? 

Which wire do I test with the positive side of my meter?

What Ohms reading am I looking for?

What Ohms setting does my meter need to be on?

Regards Joe 

Best place to start is the Yamaha Service Manual in the Tech Library here. 

Hi thank you I've looked on here I can only find how to test coil whilst engine is running I'm hoping you can test the charging coil of the bike with a meter 

You didn't look hard enough.  The Yamaha manual should answer all of your questions. 

yamaha-enduros.com/index.php/service-man...ctory-service-manual

Yes, they have "engine running tests" but if you keep reading they have the resistance checks you're asking about.  (page 125 of the manual)

Thank you so much your help and knowledge is very much appreciated kind regards Joe

Greetings from Tennessee  

Welcome from NZ. Here's a screen shot link of the page you need.
But personaly i like to just test it running,
Not that i know what those reading should be but if there's more output than the lights need & leaves enough to raise the votage on the battery then must be good. I'm guessing a bit that the green/red is a higher daytime output for the battery charging side but happy to be corrected.
Not sure if those ran a single wire regulator to save the bulbs in the case of an empty battery or battery removed but its a good idea to have one regardless.
It's very low resistances you're looking for & i don't know how far from those determine if faulty hence as i say, i like to run it & see!!.
photos.app.goo.gl/GNHfMWxiKY637oR47
Pic is a bit blurry sorry.
Do you have a particular issue you're trying to track down?.