Im not actually sure if the drilings in the side of the flywheel are for ballancing it , im only assuming that. I also found another FOTO1971 tha only had 4 drillings , it did have the shouldered edge and the seller did say it came out of a 74 DT250A

In the 1974 redesign of the 250/360, the case opening the flywheel spins inside was made smaller...  just small enough that the 73 and earlier flywheel will just barely rub the 1974-on case.  I've always thought that might be why the step was machined in the 74 models?

And pretty sure the holes are balance holes.

Thanks MARKT, I was just thinking about the rotor again and what you said about the flywheel being machined on the edge for clearance, I haven't tried the rotor yet but it should be clear?, when I do, if it rubs or not that being said if it does rub it would have to be from an earlier model? I did manage to stitch the broken wire on the lighting coil back together not sure if it will work, but trying anyways

 

Can't really see it all that great but I twisted the 2 ends back together

 

From your picture it looks like your points rubbing block ( heal ) is worn down maybe just the angle of the picture 

Me too, & looks like fiber block is totaly missing. Hope it's just my screen. & i'd missed seeing it first time around--blind as a bat 'me'.

 

Yes , points will be replaced , not sure about the condenser. I have new engine gasket kit and the left crank seal so far I haven't really started working on the engine yet , not sure what it needs yet . I'm just about done with the bike reassembly , powdercoated frame and all the black parts still have to get kick stand and bash guard powdercoated , put some new shinko tires, i used 3 screwdrivers to do that job , happy with that. found a good used rear rim on eBay .
I've never taken apart a Yamaha engine , done a few triumph 650's can't be anymore of a challenge than they were , it's all fun. I was wondering about the exhaust , someone told me to light it on fire to burn out the carbon , not sure about that. I got a new wiring harness , very nicely made from endurodoctor, I think ?  Got a new seat pan and foam from kdi and the cover from up north nicely made  it came out good , ive got the carb apart and clean need the air filter still . Any pointers on my engine dismantle greatly appreciated.
thanks