Okay, I need help...and not the kind my wife says I need. I completely rebuilt my '69 Commando a couple of years ago. Engine down to last nut and bolt. After a couple minor break-in issues, it has been running strong. Taken several hundred + mile trips without incident. About 2,500 miles total since rebuild. When rebuilt went with electronic ignition (Pazon), Mecuni carb, new German canister coils, new wiring to coils, new spark plug wires. I seem to have developed an intermittent firing issue. Happens in a funny way. First time it happened I took it to work some 14 + miles. Fired up first kick in morning and went like a bear to the office. End of day fired up great (with choke, as always) but then when warmed up and choke off, ran very poorly, backfiring, barely could keep it running for about two miles. Then all of a sudden, it started firing well and ran great all way home. I attributed to bit of bad gas (hopeful and not very logical I know) Next time out, same thing...ran great to work, but on way out at end of day, terrible missing etc. for about 2-3 miles and then bang...starts running fine again. That evening stopped at friend's shop. When went to start it, backfiring so bad flames shooting out of back...had to get a ride home. Went back to shop next day, took tank off and checked all wires to coils, plugs. Found a couple loose connections and tightened them but no smoking gun. Check timing. Dead on. Plugs sooty (as might expect) so blasted them. Bike started like a charm and took out for a good run. No problem. Next day checked plugs. Still a little sooty so leaned out mixture. Started great and ran great on another test. Plugs looked better after ... so all fixed! (Right) Few days later ran 20 miles and was great. Later in day, started back up and again backfiring, shooting flames (think mostly on right side). A friend says that he thinks I am fouling plugs by running rich...he suggests dropping the needle in the carb. I say how could it run fine for 2,500 miles and then run great or not, intermittently, if that was the issue? When I first rebuilt the bike, I had intermittent running, esp. when bike was hot. Turned out the coils were bad so I bought the new ones that are on the bike and that ended that problem. This intermittent misfiring acts like the same issue but the periods of running good and bad are longer and often when cold, not when hot. I could just swap out the coils for new ones, but I hate throwing new parts at a problem. Can a coil be intermittent in both hot and cold state? Any thoughts... :?