Definitive Source of Information on Dual Plugging
I still have my paper copy of this from when i dual-plugged my '78 R100RS.
Dual plugging was done to compensate for lower octane fuels that were becoming more prevalent in the early 80's, for engines designed to run on higher octane gas. Primary effect was to eliminate pinging, or pre-detonation. A side benefit was slightly improved performance overall. If everything in the d-p set-up was done correctly, starting should have improved as well, or at least it would not have gotten worse. Those above who said their bike was hard to start... something was amiss in your set-up (maybe a cracked or defective coil, incorrect timing, etc.)