Before you go replacing stuff, try to eliminate some possible causes, You went to school for this type stuff, what do they teach you these days about diagnosis?
Dont guess, use process of elimination.
If you done have a service manual, download one from my link below.
Check your fuel vank vent, spiders like to nest there and create all kinds of problems.
When the bike wont start, are you getting spark on both cylinders, at all the plugs?
does it fire on one cylinder or neither?
If you didnt use NGK or Denso spark plugs, you need to. best plugs on the market, either of them.. they do not need to be gapped as they come pregapped.
are the plugs sooty?
when it doesnt start do you smell fuel? open a carb drain and see if you have fuel in the bowls.
Check the 3 yellow wires at the stator connector.
And by the way, replace that float valve. get a K&L kit off ebay for about $25.00, get 2 while your at it.
That bike has a fuel pump, and a fuel filter.