You have an irregular spark.
The inductive timing light works well. If it's irregular, then the wire's not conducting, and the plugs not firing.
Check everything and
Replace the plugs. Again....
I used a timing light for ignition timing and it was a disaster. It was like a 70's Rock show...real exciting but totally wrong...
I had much better success with the static timing method...
Rotate the crank until the points open.
'74 Guzzi Eldorado
'95 R100 Mystic
danedg screwed with this post 06-26-2013 at 02:24 PM