Need help troubleshooting this one. After filling the tank on my 36k mile R100R with non-ethanol 92 octane, the bike started misfiring and backfiring badly. I rode for about 4 miles over 4k rpms and the bike smoothed out. Eventually the problem diminished but never went away even after refilling the tank 3 times with 2 octane ethanol gas. After riding 500 miles to get home I parked the bike and changed spark plugs and replaced the air filter before a month-long pause in my riding.
I started the bike tonight and it took 30-40 seconds for it to finally start (normmally would start in 2-3 seconds). After I got it running I went for a ride and had a bad case of misfiing and backfiring until I was able to warm the engine and run it over 4k rpm. Same problem, misfiring and backfiring.
As background, the carbs were rebuilt 5k miles ago, valves adjusted 6k miles ago, new in-line fuel filters 5k miles ago and carbs synced 3k miles ago.
What should I try next, new plug wires, new coils, new Hall-effect sensor?
Thanks in advance for any and all advice!