Hello folks this is my first post.  I found your awesome yamaha enduro community by doing a google search of my problem which is the subject of this thread.  I am not sure if this is where I should post, please let me know.  I am trying to get this bike to start.  It's a barn find.  It has good compression @ 120 psi.  When I first started poking around I discovered the spark was very weak so I replaced the coil.  I believe it is a good quality coil made for the  model. 
Now that I replaced the coil and wired it  back exactly like it was before (using the black wire coming up from the magneto, the other wires were cut off) I am getting zero spark!   Yes I have checked for ground.  Yes I have checked the continuity.  Another thing I did while poking around was remove the cover of the magneto, maybe I somehow screwed it up??  

This might be stating the obvious but what happens when you put the old coil back on?

(many people here have replaced their coil with new aftermarket (usually from China) and found that they got spark back and the engine running by using the old coil)

Most common thing that goes wrong in my experience is a film builds up on the point contacts... simply clean the contacts... and you do NOT need to disassemble the ignition to clean the points... and spark is back.

(Or as Morley would say "give the points a scratch")

Make sure plug gap is 0.020" - 0.024"... new plugs come gapped too wide... and spark never looks that strong on these old magnetos... they don't have 50,000 volts... more like 10,000 to 15,000 which is on the edge of being "just enough".

Welcome from NZ.
So i'd better say it then lol. Give the points a scratch. When you had the cover of, did you do anything while in there or just look. So the black is going straight to the coil. The coil is mounted so its grounded through the coil mount. As Mark said, try the old coil. Spark never looks that great, but it'd make your hair stand on end if ya grabbed the plug. Sometimes the black from the mag has a short covered wire sticking out on the way up from the mag. Don't earth that or no spark. The 360's can kick back hard, so make sure you kick it hard & follow through to avoid kickback until it hits the footrest. Pics would be good sometime--we love pics. Welcome again & cheers Morley. ps, where are you situated?. We have people from all corners of the world which makes this site just great.

If you replaced the plug and cap make sure you don't have a resistor cap and resistor plug. On my dad's 72 he put a NGK R plug and new cap. I happened to be on my Honda the day I was visiting that took the same non-resistor plug. We put that in and it fired right up. Ended up going with a champion non resistor plug as the NGK is no longer made.