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Slip On Mufflers


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Many have asked the question of whether slip on mufflers can be added with no other modifications on the Harleys.

The 06 FXDWG and later 07- touring bikes that have the 02 sensors on them can adjust the fuel to a certain extent but being narrow band in nature, they can only adjust so much and mostly in cruise mode only.
They are a step in the right direction but wide band sensors would give better control of the mixture over a wider range with some of the more sophisticated ECM replacements that can monitor and adjust the fuel/air mixtures throughout the RPM ranges..

The EPA requirements on the newer bikes have leaned out the mixtures to the extent that many bike are experiencing problems with lean surging and hesitations.

The dealers are telling customers in many cases that fuel enrichment isn't necessary but I disagree with their reasoning on this subject. If the basic fuel enrichment units are used like a TFI , DFO, HD Fueller or PC III, plus a bunch of other similar units available that work similarly , the results will be most noticeable.

If you add slip ons and especially if you add a stage 1 intake to the engine, fuel enrichment should be done to prevent damage to the engine in the long run. Heat buildup will be reduced somewhat with the richer mixtures and overall performance will be enhanced with the addition of some additional fuel to the mixture.

These are meant to be a guideline only for a better running engine on the later model bikes and to give you an idea of what is available to do it.

Any questions can be posted in the proper forum pertaining to the fuel enhancements on these bikes.