Won't Start Without Starting Fluid, Backfiring, Very Rough While Cold

So, since this spring, our 2 year old cafe bike will not start without starting fluid. The carbs were meticulously (and I mean meticulously) cleaned and rebuilt during the build 2 years ago (completely dissassembled and cleaned, replace idle mixture needle o-rings and throttle shaft o-rings, float valves replaced, float height set, new gaskets). The intake boots look in good shape. Full choke and a tiny shot of starting fluid in each pod and she starts right up although she will stutter and backfire regularly for about 3 minutes or so while you gently goose the throttle back and fourth until warm and then run pretty dam smooth. At that point the choke can be pushed in. Push in the choke anytime before that and she'll die. The mods to the bike include pods (we kept the factory exhaust and have not jetted the carbs), and Iridium plugs (NGK BPR7EIX) with zero resistance caps. I figure the carbs need to be cleaned again but since the bike will be down for a few days I figure I should also take care of anything else that might be causing it (adjusting the valves???). I recently replaced the plugs and despite the pods, the plugs look like its running rich. Any hints/advice would be appreciated.

I had the iridium plugs in my bike they didn't impress me,I think they run to hot of a spark.When she was running I put champions back in it.You need to rejet for the pod filters and it wont probably wont run as rich since the pods allow more airflow.See if that helps.

I would make sure the valves are adjusted proper and then sync the carbs. Have you done a compression test on the bike? What are your idle mix screws set at?

Xschris: Compression is 140 in each cylinder, Idle screws set 3 tuns out (tried turning them in when build completed and 3 turns out is where it seemed to run best). Carbs were bench synced using the index card method prior to initial install after the rebuild. Valves do shound chattery so I expect I will adjust them when I get into it. Thank you for your reply.

Scorpio1963: I would expect the bike to run a little lean already because the pods already allow for extra airflow but the plugs are black and wet. Jetting generally is for richer fuel flow. Since the bike was stock and somewhat neglected when purchased I doubt the PO (or PPO or maybe PPPO?) dicked with the jets already but I did not identify the specific jets that were installed, just cleaned them with the rest of the carbs (2 years ago). Thanks for your reply.

Adjust the valves, sync the carbs with a manometer and check to see what size the pilot jets are.

Do you know what size jets are in the carbs both mains and pilot?Just a thought but maybe the mains and pilot are too big and you need to down size.Also have you tried leaning the fuel air mix screws also after any changes are made like xschris said sync the carbs which should help.

When I clean the carbs (soon) I will check the jets. I strongly suspect they are stock. I did not have this starting problem after the initial build (first year of use) and the jets are the same. I did try leaning the mixture screws during the initial build and 3 turns out was where it ran best. It's always run pretty ruogh on startup (sputtering, coughing, and backfires) but smooths out nicely once warm. That would tend to lead one to think its running too lean since warm air is less dense than cold air the mixture would richen up as it warms up and starts running better..

Guess its time to clean carbs again, adjust valves and sync carbs. Then I'll see how it starts and runs. I'll probably get to that next week while my son (the rider) is away for the week.

Thank you both for the inputs.