My 04 harley night train keeps fouling plugs left and right i richened the mixture with a 52 pilot jet. ran fine for awhile then fouled again could this be an electrical problem?

If the plug is fouling only after 20km, you must be running on a very rich mixture... Please try a smaller jet am do some "plug chops" :)

if your still fouling plugs then you still need to go with smaller # on main jet...are you spooging allot out of pipe and muffler? then your to rich still,smaller jet size!!!! 32:1 is a good mix ratio

Odds are that you need to richen up your carb. You said that you can smell that the mixture is very rich. This is true if you're using the enricher. The enricher is designed to be very rich and it will foul plugs if you allow it to run too long. I usually run it only long enough to allow me to set the throttle lock and keep the bike running at a high idle without the enricher.

To actually remedy the problem and shorten the time you have to run the enricher, you probably need to enriched the low speed jet. The carb comes jetted very lean from the factory and usually does a lot of coughing and spitting out of the carb. If your slow speed jet is a #45, you need to go to either a #48 or a #50 slow jet.

Good luck
steve

1. First check you carburetor manifolds for intake leak warm the engine up and spray WD40 all around the where the manifold connects to the heads if the rpms change when you do thins you have leak replace the gaskets.
2. Your carburetor may need cleaning due to a blocked or partially blocked low speed circuit.

I would say that something has changed since you had the work done. You said that it ran good and got 54 mpg (you said "mph" but I think you meant MPG") after the work was done. Now, it's backfireing, sputtering, and getting 37 mpg with dry black deposits on the plugs. Something has changed.

Considering that you didn't mention anything you changed, the only thing that has changed is the weather, it has turned cold. Cold air is more dense than hot air therefore, your carb should be running leaner, not richer. But, I'd be willing to bet that you're allowing your bike to run longer with the enricher on when warming it up before a ride. Am I right?

The enricher circuit is a very rich mixture. It's rich enough that if you allow your engine to run too long with the enricher on, it will foul your plugs. Fouled plugs are indicated by a black sooty deposit on them. In my experience, once a Sportster fouls a plug, it will not clean itself like a Big Twin will. Why this is I have no idea but that's my experience. You'll either have to replace the plugs or get them cleaned somewhere. I clean them in a glass beading machine but you have to blow them out very well before reinstalling them. I also put a little anti-seize on the threads to keep from damaging the spark plug hole threads.

Try installing a new set of plugs and when you start your bike, only run the enricher long enough to warm the bike to the point where you can keep it running with the throttle lock knob to bring the engine to operating temperature. That enricher is a plug killer.

The only other thing I can figure is that the main jet has come loose and fallen out, trash in the needle and seat, a vacuum leak on the front head at the intake manifold, the VOES, or petcock. If it ran good in warm weather with the 170 main, it should run good or may a tad lean in cold weather.

Why 50:1?
All bikes should be 32:1, and then jet to match that.
Your oil is fine, and yes...go smaller on the pilot.

NGK brand spark plug BR8ECMVX is the stock plug for the bike. The proper gas / oil mix is 32 to 1. That means 4 ounces of 2 stroke oil per gallon of gas. The posting was not clear as to just what the problem is. If you are burning up plugs there may be a air leak in the intake system making the bike run lean. A lean fuel mix runs hot.

Yours must be one of the last years with a carby? Sounds like a low speed jetting problem. Bike may be running lean on the low speed jetting. Suggest starting by adjusting air mixture screw ( pilot air screw) out to 3-3.5 turns, very gently and by 1/4 turns to richen the idle mixture. Once the needle jet comes into play, she clearly runs nicely, so it's most likely that air screw as MoCo set it lean. Good Luck