Dt175 ignition timing questions

[Braap2thefuture]

Hey guys, I picked up a 75 dt175 for 100 bucks and without much effort got her running. Everything seemed OK, I was disappointed with the lack of power but figured that was just how it was with an old bike and gas nowadays. Plug looked good without changing jetting

I put a little over 100 miles on it then had it seize. Got a piston, had it bored and it was good to go. I had to orginally put the bike together in a hurry (this was for dirtbag challenge) and now after I did the top end I wanted to check all the things I didn't have time for. And, having finally found a manual online for it, I was good to go. One of those things is timing. Reason this is suspect is I noticed what sounded to me like pre ignition.

First, I found out someone had stolen my multimeter I left out in my truck so i figured I'd at least check point gap to get an idea of where things were at. Well, turned out it was way too small, I adjusted it to spec and took her out and WOW the thing took off like a rocket! Would lift the front a tad gassing it in third. I was super stoked! Feeling inspired I went and bought another multimeter thinking I was going to completely dial it in.

 

Now, questions:

Firstly, I have a dial gauge so I'm good there. The manual says to hook up the point checker to ground and the black wire from the magneto. I hook the multimeter up to these wires with the continuity buzzer and no matter what the position of the flywheel or even visibly seeing the points open its buzzing constantly. It would appear both "sides" of the points are attached to the case and thereby ground, so how is this supposed to work? I've done points on a ton of bikes and old 2t's and don't remember having an issue with this...

The other thing odd to me is I'm used to these old Yamahas having 3 screws to rotate the ignition plate. This one does not and would appear ignition timing is solely dependent on point setting, is this correct?

The mechanical advance is a little different too on this bike and I'm not sure it's operating correctly. With the flywheel off, should the mechanism spring back and forth when moved? It sticks and with a drop of lube there was no change. Also seems like the spring doesn't pull on it any like it's too long of a spring

 

Thanks in advance for any input!

[Braap2thefuture]

OK I figured it out. You cannot use the continuity test. You have to read ohms. In my case it was .4-.6 was closed and 2 was open. I had tried this earlier but just kept getting random readings and I discovered today that if you don't turn the flywheel SUPER gently the readings will go haywire. Also, fyi, the tiniest adjustment in points makes for a huge change in timing. Also, I'm used to setting timing and seperatly checking point gap. Not so with the DT. You're setting the timing by changing the points, then check gap to make sure they aren't too worn. I'm also reasonably convinced the advance is probably working, seems to move and spring back easier with the flywheel on

 

Anyway, runs killer now! And hopefully my struggle helps someone