Question about 2003 Harley Davidson FLSTFI Fat Boy

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Wherearecarbajustmentson03harleyfatboy - 2003 Harley Davidson FLSTFI Fat Boy

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I have a constant flow of fuel from the tube at the bottom of the carb bowl. The bike had not been run for eight years so you cab imagine how much cleaning I had to do. One of the things I did was soak the bowl in strong carb cleaner. The is tube in the bowl that appears to be an over flow tube the routs to the tube at the bottom outside the bowl. At the bottom of the inside of the bowl the is a small hole the is allowing the fuel to run out the tube at the bottom of the bowl. I suspect the carb cleaner may have destroyed a plug the closed off the small hole at eh bottom of the bowl. Any ideas?

Posted on Oct 10, 2013

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If the carb is a factory carb and has not been modified, there is only one adjustment on the carb. This is the throttle stop screw to set the idle speed with. The only other adjustment is the idle mixture adjuster screw but it's covered with an "anti-tamper" plug to keep people from messing with it. It has been set at the factory to meet EPA regulations. You cannot adjust the idle mixture unless you take the carb off the bike and locate the small plug just behind the float bowl. Drill a small hole in the plug. Drill lightly and just enough to punch through the plug or you'll damage the brass mixture screw under the plug. Then put a sheet metal screw into the hole and pull the plug out. Then, you'll see the idle mixture screw that the EPA does not want you to adjust. Once this is done, take the float bowl off and locate the slow speed jet in the carb. It will down in a deep hole beside the main jet holder. Take it out with a screwdriver and see what size it is. It should be a #45. Replace it with a #48 or a #50. While you're at it, take the top off the carb and remove the slide. Take the needle holder out of the slide and remove the needle. Put a 3 mm flat washer that is about 0.020" thick on the needle from the long end. Use a small dab of grease to hold the washer on the needle and reassemble the carb. Be very careful to get the slide diaphragm back into it's slot around the top of the carb. Do not pinch it or you'll have to replace the slide and diaphragm. It ain't cheap. Put your carb back on the engine with a new intake manifold to carb seal. Start the engine and allow it to warm up and then adjust the idle mixture to the highest smoothest idle. I believe the bike will run a lot better and a lot cooler.

Good Luck

Posted on May 29, 2011


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