2005 1200 custom carb problem

A week ago today I put slip on drag style pipes (with baffles) and a K&N Stage 1 air filter kit on my bike. It has a 42 slow jet in it so naturally I assumed I neede to swap a 45 for it. The problems started then. I got the 45 used so that may be the issue. Anyway I put the 45 in and made required adjustments with mix screw and the bike would not run on its own....had to constantly be working throttle to keep running while adjusting everything....it never did even out. So I took it all apart again to make sure it was all clean and tried again. Same results after that. Ok. Now I put the 42 back in and readjusted everything. It idles great and runs great at highway speed..the problem is still a few carb farts and at 30 mph it surges just bit unless it is under a constant load. can anyone help me? I have read mixed reviews on drilling the slide and think maybe i need to buy a new 45 jet and try again because the one I have may have been modified. Thanks guys!

yes, disassemble and look for these three things.

1. Look for a bad accelerator pump diaphragm.
2. Look for a tear in the rubber diaphragm that is just under the carb cover.
3. Look for drilled hole in the slide. Like you I have heard mixed reviews on drilling the slide but everyone here will say not to do it. I haven't and won't. Easy to find a new slide if that is the case.

Have there been other modifications made to the bike other than the Stage 1 kit that you did? If not, I would think that a 45 pilot is just way too big, and there certainly is no reason to change the needle. More information about your set up will help everyone help you diagnose the problem...

I checked and re checked the diaphragm many times and looks great to me and even had a buddy look at it to see if I missed something. Pretty sure the accelerator pump works like it should cause I can see it squirt in carb. To answer your question about other mods. the only other thing I did was put some slip on mufflers on it...they have baffles in them. The carb had never been apart before I took it apart. It already has a 180 main in it. Im leaning toward the 45 jet that I used was possibly drilled by someone cause I got it used and most people tell me that is what it needs ( a 45 jet )

also took my plugs out and the front one was a bit white chalky looking and the rear was clean grayish looking

I installed my carb kit last Wednesday and all seems to be working ok after warm up...only thing I dont like is its still a cold blooded starter...and I mean real cold blooded. It has new plugs in it runs fine when warmed up but puzzles me until it warm. Ive seen other guys at work that dont even choke their bike when we leave but I have to or it wont stay running.