I picked up this Shovel last fall. Rode to Vintage Bike night yesterday and it ran really good but when I got home it was missing and the rear plug is (dry) carbon fouled. Not all oily and no smoke out the pipes. This is the 2nd plug that has fouled. The original was a H 3-4 and this one was an Autolite 85. The front one seems to be normal firing and looks ok. One post I read says the spray bar in the throttle body might be spraying left toward the rear cyl, but it doesn't smell like raw fuel on the plug. With a new plug, the bike runs pretty good. Has a Super E carb and electronic ignition. Looking for some directions. This is my first "running" Shovel




I had HD plugs in both front and rear, rear one fouled and I replaced both with Autolite 85's. When the rear Autolite fouled, I just grabbed the HD that was in the front before, and put it in there. This fouled after about 20 miles. Top one in the pic is the rear plug.

 

V-twins like to run rich on the rear cylinder anyways...and if you accelerator pump is favoring that side it can make it worse...might try turning down the pump a little. You might try some NGK plugs...they don't foul as easy...Worse case you could try running a hotter plug in the rear cylinder. I would run a compression and leak-down test to make sure that cylinder is healthy.

 

I put in new plugs last nights and fired it up and it does have a little black smoke out the rear cyl pipe. Valve seals? How hard are they to change?

 

Stock 74 FXE's did not use valve seals. Make sure your point gap is correct for the ignition you are running. Points are tighter then electronic. Original Harley 3-4 plugs are the same as Champion J12Y.

 

and if you accelerator pump is favoring that side it can make it worse ... very common too. Pop off the air cleaner and watch the "squirt" from the pump. Optimally it should hit the center of the intake manifold.

 

27062-78 Seals - 66 to 84 Big Twins

http://www.granitestateharleystore.c...-A040/02430015


It sure looks like a fuel problem though :>)

 

Problem is solved. I sold the bike. LOL Thanks for all the input, brothers.

 

Why do V twins run richer on the rear cylinder? My plugs don't foul and the bikes run well but I do notice that the rear plug is always darker than the front plug.

 

Get in your car...set a cup of coffee on the dash...now slam on the gas...where does the coffee go?

Basically the fuel in the intake does the same thing, enough to make the rear run richer...if you run a single plane intake on a V-8 you will get the same effect also.

 

Thanks for the explanation and it makes sense. I think I'll skip the experiment with the coffee cup on the dash though.