Main Motorcycle: 2002 Thunderbird
Join Date: Dec 2012
Location: Concord, NC
Other Motorcycle: T-Bird lives alone
Do you smell gas as you're cranking with no sputtering/sparking?
42 mains may be a little rich for startup at 2.5 turns, even with air intake mods. You may want to back down to 2 turns.
Mine are happy at 1 7/8 turns.
Also, since the carbs were off, hopefully you didn't disturb the balance screws...that will also add problems at cold starts.
One problem with these motors is that they can be very picky at startup.
Make sure your battery is nicely juiced up, and then go after confirming your spark if nothing fires.