Hi everyone, I have a 1974 DT125 with electric start. Trying to start my freshly rebuilt motor. I have good spark, fuel, but no start. I’m assuming it’s a timing issue. Looking for confirmation I understand this procedure.

So, after setting the motor at 1.8 BTDC and adjusting the timing plate the next step is to check when the contact breaker opens when the cam meets the timing plate. Now my question is when this happens how / where do I adjust to Advance and Retard the breaker? Reading on here am I correct to say the points aren’t really adjustable, and that once I get the breaker opening at the timing mark and the gap is out of spec, replace points? 

First time working with any kind of points ignition, please bear with me. I attached the diagram if someone can tell me where to adjust for the advance / retard.

Thank you!

  

Also why I have everyone, the bike is a 74’ and I bought the donor motor that was supposedly from a 75’. When I look points for a 1974 they look like the ones in the photo. If you look at the photos of my bike you’ll notice the points have serated teeth. wondering if I’m having a compatibility issue with my donor
motor and my 74’ bike. I do have good spark though…
 

If you read the manual, you'll find the correct method for the 125 starter/generator.  It's different than magneto.

1. adjust maximum point gap
2. block open advance mechanisn (aka governor)
3. Set points to open at proper distance BTDC
4. unblock advance.

No "compatibility" problem unless your original engine had a magneto which is not likely if you are in the US.  US model 125's enduros had the 12v starter/generator from 69-76.  Other countries had a 6v magneto 125 available during those years.

Those points in the picture are for a magneto 125.  You have the starter/generator model which takes completely different points. 

Note that on a magneto you adjust the point gap to set timing. 

On the 12v generator you do not set timing with point gap!  The "serrations" are related to being able to move the points assembly to set timing without changing the point gap.  Again, read the manual and it should make more sense, if not, ask questions.

Thank you, so adjust stationary point gap first then adjust timing by moving the breaker assembly (the serrations). I have my motor set at 1.8 BTDC and my manual was confusing me so your reply is helpful.

Remember to block the advance open before setting timing.

10-4 , thanks again

Here’s a old picture that may help. On left is simple non adjustable points. When fiber block that rides on cam wears down so point gap isn’t wide enough. Other two have setup where you first turn motor till bump on cam opens points to max then turn adjustable screw to proper gap. That is the style you want. They are quite expensive like $60 from memory.  Either style though you set timing by loosening the two screws holding down the whole point assembly and rotating it.
 

Thanks for that photo, looks like I have a 76’ generator.
So with my dial indicator used per procedure I arrived here 1.8 BTDC. So it’s not even close to being able to fall with the points advance / retard range. Does this mean the cam plate or something else is installed out of whack.

 

Common things to consider:

1. Are you at BTDC and not ATDC?  Which direction did you rotate the engine from TDC?  CW or CCW?  (I get it backwards a lot.)

2. Have you done any parts swapping?  There are two basic versions of that system that are interchangeable as a set, but not necessary piece by piece. Reports are the later (slightly larger armature) has the governor (advance mechanism with points cam) indexed about 180 degrees from the same part on the earlier model.

3.  Armature key could have sheared or fallen out during assembly and the armature is not indexed to the crank properly.