Just picked up an 04 1200 custom yesterday. Looks and runs ALMOST right. Looks like previous owner installed some bassani sweeper pipes (which are almost too loud if you ask me) and a K&n high flo. The air filter does not look like the SE one. It's circular/conical and maybe 4 or 5" diameter.

After riding about a 100 miles of owning the bike, it's starting to back fire when RPM's drop when in neutral and revving up OR on decelleration. Some minor blue flames come out of the exhuast on the backfire. Brought the bike to NewRoc Harley in NY and their mechanic drove it around the lot for 15 seconds and said it looks like it may need a carb re- cleaning or rejet? I don't know how sure he is b/c he wasn't able to look at anything else. I'm reading on the boards that this crankcase position sensor may be an issue, replacing air filters, carbs, etcc.. I have no idea where to start.

 

I would start with the cheaper stuff first. I don't know much about carbs but a rejet/carb cleaning/adjusting sounds like a good cheap place to start.

 

i had same problem it was my sparkplugs

 

just replaced with original plugs? i'll start there along with a carb cleaning and see what happens

 

If running pipes with no baffles or restrictions, you will get a lot of deceleration popping. It will sound like a jake-brake at times. It is very annoying to most people, however some riders seem to think it's cool. (see 3 posts down )

 

After the plugs/carb cleaning your planning to do,check the exhaust flanges...make sure the pipes are mounted to the proper torque specs...
Had mine get a bit loose,and the end result was popping on decel...that little exhaust leak by the cylinder head was the culprit...

 

Decel popping + blue exhaust flames = running lean.

 

No blue flames on mine but does pop occasionally on decel. No popping on neutral or accel. I like it, sounds like gunshots. Which makes me blend in while riding in LA.