Poor gas mileage-need advice

[samr]

I have a 75 Sportster - Ironhead. Bored twice over-performance pistons-performance cam - 280 valve springs. I don't know the details of pistons and cams because I didnt do it - previous owner did. It is has S&S Shorty E carb. with .028 intermediate jet and .066 Main jet. I have cleaned the carb and set float level correct. I turn pepcock off anytime the bike is off. Idles fine but does have a hesitation when I spike the throttle from idle. I have adjusted the accelerator pump adjustment but it seems to make no difference. Bottom line is I am getting 15mpg or less. Looking for some of you experienced braineaces to give me some suggestions. I have only owned this bike less than a month - the previous owner commented that the gas mileage was not good. I didn't expect it to the this bad - should I have? Sam

[claydbal]

35 miles to the tank? i would think you would foul plugs before you got out of the driveway. had severl hotrod ironheads and would look for gas when odometer hit 80 miles. i dont know how it runs long enuff to tell MPG. time to blueprint everything if you gonna keep that tranny eater.

[samr]

Originally Posted by claydbal

35 miles to the tank? i would think you would foul plugs before you got out of the driveway. had severl hotrod ironheads and would look for gas when odometer hit 80 miles. i dont know how it runs long enuff to tell MPG. time to blueprint everything if you gonna keep that tranny eater.

You are correct - my thoughts exactly - and yes it did foul a plug. Here is the outcome. Found lots of trash in the Accellerator adjuster of the S&S shorty E carb. Also found bowl height adjustment way out. Bottom line is the gas was probably overflowing out the vent line and remainder going around pistons into gas. Changed the oil, Rebuilt carb and set bowl height correct. Also made a mental note to NEVER leave petcock open when Bike is not running. Running fantastic now with no massive gas use.
Sam