#6 Cylinder Running Rich After Desmog.

[hueco]

All other plugs look normal. #6 plug is very black. This is carb with vacuum tube going to petcock. My guess is a hole in petcock diaphragm or bad diaphragm with fuel getting sucked in to carb. All and any opinions appreciated. Running like crap. Thanks. Lee.

[pancho]

Sounds like a good place to start looking for what is causing the #6 plug to be running rich hueco,, pull that hose and shake it,, see if there has been gas in there.

Weather that is what is causing it to be "Running like crap.", fix that first and see. Then, get a dental mirror and see if all the airbox boots are seated properly,, it can be a chore to get them all on correctly.

[hubcapsc]

There's a weep hole on the bottom of the petcock. The gas would
rather go out the weep hole than down the vacuum line. Is the weep
hole plugged? Is the petcock wet with gas? My buddy Gary got a
Valkyrie with a bad petcock, and when we fixed it (cover set) we
noticed that the previous owner had purposely plugged the weep
hole. Gary had raw gas going down the vacuum line to #6, and enough
raw gas spewed out the muffler to make a dead spot in the grass
when he cranked the bike...

-Mike

[da prez]

  A ruptured diaphragm in the petcock will over fuel the cylinder. It is not that hard of a fix. They do wear out and need to be changed.

                                  da prez

[longrider]

Check the pilot screw on 6 as well.   Too far open will make it run rich on it