Motorcycle Repair: 1979 Honda CB75k No Spark on Two Cylanders, coils, last friday

Question
Hello there,
Well I'm Having and issue and i am newb to motorcycles. I bought this bike
back in June. The bike ran great up until this last friday. I had been cruising in
down town Mpls and the bike had started to sputter so i had thought i
needed to switch to my reserve, that was not the case. We had thought the
bike may have been to hot so we let it cool for a hour and it started up just
fine. I got on the freeway to get home and get air moving over the engine
thinking it was getting too hot when not long after it sputtered and died
again.

So upon some inspections i was told to check the petcock valve and that
seems fine. It only seems to act up once it starts to get warmed up. The bike
was already hot when i got the idea to check the plugs for spark. The both of
the far right plugs have great spark but the both left have little to no spark.
What can cause this?

Any help will be greatly appreciated,
Tim

Answer
I hate to say it Tim but this has me puzzled.  The inside two out side plugs fire at the same time and the two inside cylinder fire together.  So the part that I can't figure out is why one side of each coil is acting up.  Normally, a coil will go bad when it gets hot, break down and stop firing the plugs but it will effect both plugs on that coil not just one.  It sure sounds like the coils are breaking down when hot but I can't reconcile why both plugs on the right are loosing spark.  I can't think of anything to explain this behavior.

Regards
Rich