2002 R1100S overfueling????

[docsouce]

I'm finding that my new (new to me) 2002 R1100S (13,000mi) seems to be running a bit rich. I'm getting around 36-38 mpg and the pipes and plugs are black with carbon. I talked with the dealer and he said that that is because it is a single spark plug motor. I don't know what one plug has to do with running clean but that is what was told to me. 2 of my riding buddies are running single plug R1100S's and they are getting around 42-44mpg. My bike is stock. No pipes or chips. It starts OK and runs great........I'm just uncomfortable with this apparenty rich running situation..Thoughts...

[PGlaves]

Black plugs are a good sign that it is running too rich, provided that they are the specified plug and provided you are checking them at a point in time that idling and slow running haven't carboned them up a bit. I do a "plug chop" test. Go for a ride and find a convenient place to coast into and pull the plugs. Rest areas and convenient roadside parking lots are good. Approach at highway speed, cut the ignition with the kill switch and coast in to your spot.

Let it cool a bit and then pull and examine the plugs. Even going slow the last mile down a gravel road to my house has blackened up the plugs, so the plug chop test is much more reliable.

First, suspect that the air filter might be dirty. That can cause a rich mixture.

Second, suspect a poorly set Throttle Position Sensor. That can cause a rich mixture.

Third, suspect a faulty fuel pressure regulator - if the pressure is too high that can cause a rich mixture.

After that - get it on an analyzer and see what you have. I assume this is a stock bike, but kludged chips, replacement injectors from Ford Bronco's and any number of well meaning and poor performing modifications have been made to bikes over the years.