Here goes and I am hoping that some of you have suggestions . . .
96FXDS, carbed and mostly stock, bought it about 4 years ago with about 14k kilos/9k miles on it, now has about 90k kilos/65k miles on it (Canadian bike that snuck through the fence up there!)

I do my own service; oil and filter at 5k kilos/3500 miles, full fluid change at 10k kilos/7000 miles. Used to do the full Harley/Screaming Eagles thing (Oil, filters, plugs, wires, etc.). But now I do mostly aftermarket from JP Cycles. (RevTech Fluids, Champion Plugs, etc.

Almost a year ago I swapped out the fuel lines, accelerator cables, and a few other things for some chrome bling. Fuel lines were wrapped with a chrome sleeve. About a month later bike started running for crap, missing, spitting, backfiring, etc. I thought the fuel lines collapsed so I pulled them and checked and they were fine. Checked other components over but all looked good. Finally swapped plugs again and put in a new set of Champions. Ran like a top!!! Happy face again. Ran good for about a month or 2 and same thing; spitting, sputtering, backfiring, etc. And it kind of came and went randomly; would run good a day or 2 and then for crap again. Checked the whole fuel system from internal tank filter to carb and all was good. Checked ignition module and all the gunk it was melted down to the bottom of the case. Ran to HD and swapped it out for $145 and still ran like crap. Swapped out Screaming Eagle plug wires cause they had some grooves rugged in them. No good! Swapped plugs, happy face again! Ran like a champ. Just the other day it did it again. Cruising down the road and spitting and backfiring like crazy! Swapped plugs again!!! Happy Face!!! That is 3 sets of Champion RN12YC plugs in about 6 - 9 months! (I do about 10 - 12 k miles a year.)

My intention was to change plugs every 10k kilos/7500 miles but I don't think I have been able to go that long yet. I did buy 6 pairs of those Champions so I am not too thrilled with tossing them. Any thoughts? Anything that I may have missed?

 

Try NGK plugs.

What do the plugs look like when you take them out? Are they black?

 

What did the plugs look like when you pulled them?

 

Do you monitor your oil consumption? May be time to start. Engine may be getting tire, or you may be running too rich. Bad carb. diaphagm will do this.
Have someone ride behind you, and look for blue smoke (oil) or black smoke (running too rich) either one can foul plugs.

 

Firstly switch to NGK plugs, second, get the old Champions sand-blasted in a proper old skool plug cleaner and try them again...if they work then you are suffering from plug contamination due to either running rich or burning oil.

If the NGK's last 10K without packing in then you know the answer.

 

I truly don't recall exactly what they looked like when I pulled them but nothing jumped out and hit me. They weren't totally carboned up or oil soaked. If I recall, a grayish color with a black spot on them. I don't consider it to use oil. When I change oil and filter, the fresh oil level is about an inch over the full mark. After 3500 miles it is near or at the full mark. Most of that is coming out of the bottom of the rear jug where it is leaking enough to leave a drip after a week of not cleaning it.

Later tonight I will pull the plugs as they should have about 200 miles on them and make sure what they look like.

Thanks for all the suggestions and help!

 

You are adding too much oil.

 

If you dont have a HD manual , now is the time to purchase one.
My suggestions are to first determine why your ign. modual burned up by doing the modual and coil checks as described in the HD manual. Be sure all wiring connections are good at these units and ensure your voes. switch is ok. If we can eliminate all these then look for voltage leaks by running the bike in a dark room and look for arcing. If all is well and as you have purchased the champions as a bulk set , i would say you have a bulk set of defective champion plugs . I have had same before and dont use them now.
As advised , go to NGK etc.

 

To Beemervet: A little bit of extra oil burning up plugs??? I don't think so. Manual calls for 3 qts with filter change, which is exactly what I put in. My Ford pickup takes 6 qts which puts it a little over full on the dipstick. Normal occurance.
To Machinehead: The Ignition Module was not burned up. The insulator gunk melted out of it which a lot of people on this site have mentioned but it was still working. Drove the same before and after I swapped out the Ignition Module. I do have a coil on order that I plan to swap out. I think that Champions are just not good plugs for my bike.

 

Here are the pictures of the old plugs. Take in consideration that just before I pulled these plugs, the bike was on full choke, spitting, backfiring, never got over 20 mph and that was for about 15 - 30 minutes. I got about a mile from the house and turned around to go back. Here are the pictures.