What size slow jet needed for 2005 XL1200?

Well, I think all I was smelling was gas evaporating from the carburator, through the air filter, because it was only on hot days and causes no problems otherwise.

Anyhow, I have a new issue now. So, I recently moved from Amarillo, TX (3500 ft AMSL) to Houston area (near sea level), and the 1200 Sportster is now hesitating and backfiring at low speed acceleration, until the bike warms up real well. As stated above, in post #14, I changed the slow jet to the number 46 from the CV Performance Basic Tuner's Kit for Harley-Davidson. That was all I changed. Shall I now do more, due to the lower elevation, or replace with the original 42 jet? Or, try adjusting the mixture screw?

I'd try adjusting the mixture screw first,that will help determine if the pilot jet is too big...more than 3 1/2 turns out it's too small less than 1 1/2 turns out it's too big...if no change in idle turning all the way in (GENTLY) try a smaller pilot jet...
The K&N replacement filter in the stock backing plate isn't going to increase intake air flow very much,so I suspect the 46 pilot may be a little too big,but finding the right mixture setting will tell you for sure...

Yes,that's right....a backfire through the carb would be a lean condition..and a 46 pilot isn't too small for a 1200 Sporty,I was still thinking about him smelling gas and a backfire through the exhaust could indicate a rich condition...
Regardless, make sure there are no vacuum leaks and try adjusting the mixture setting...

Have you thoroughly checked you choke cable? Is everything there correct? Another place to look at least. Your choke could be open just enough. Have you done the propane testing on heads, rocker covers, intake gaskets, and exhaust gaskets to see if there are leaks? Have you checked to make sure that your exhaust is buttoned up tight? I had a bad head gasket a while back and I had similar symptoms as you are describing.

I just have a real problem thinking that a 46 pilot is too big for that 1200.

Wow, you all bring up good points. And, now I am thinking it could be any one of the problems stated. This could take a while to figure out, but I think I'll start by replacing the mixture screw with that of CV Performance's thumb screw.

Thanks.