I have the 07 tc96 Street Bob with 4400 miles on it, decided to put theVH slipons on it but wanted to check the spark plugs to make sure it wasn't running too leanbefore and about 200 miles after the install. They look the same kind of light gray. Is this normal for fuel ainjected motor, or are they too hot?

 

did you just install slip-ons??
or did you change the a/c also
did you have the stg 1 download done/??
if you just installed slip ons and did not do the a/c then it will be fine a little lean but ok. its a lot harder to tellif the bike is lean or rich with efi.
your probley a little lean from the factory. they all are.

 

Only slipons, will do the ac and down load later. Thanks

 

From: http://www.gnttype.org/techarea/engine/plugs.html

"A normal condition is shown below. This plug has been running at the correct temperature in a "healthy" engine. Operating in such a desirable environment results in deposits that will be light tan or gray in color with most grades of commercial gasoline."




"An example of overheating is shown below. Note the dead white or gray insulator nose which appears "blistered." Electrode gap wear rate will be considerably in excess of that normally expected. This is often caused by overadvanced ignition timing, poor engine cooling system efficiency (scale, stoppages, low level), a very lean A/F mixture, a leaking intake manifold, or the use of a spark plug too hot for the application." THis is what my 6000 mile plugs looked like ('02 Road King stock +V&H Slip Ons), plus the front cyl plug elecrode had lost its sharp square edge and was rounded.




Do a GOOGLE on "spark plug appearance". Tan/ grey is good, bone white is not so good.

 

tan and gray are fine.whites bad and black bad but will not hurt anything except millage.Also make shure its the intire electrode all the wau to first thread.If realy want to read.ride out to dragstrip and make pass on new plugs or somewhere you can hammer it for good distance,click the motor pullover and check plugs.they need to be new when starting this.

 

White to very light tan center porcelin (but with no specks/spots). Carbon at the base of the threads. grey/metallic color on the ground electrode at the tip changing color (to dk brn/black) in the middle of the bend...this is called a "burn" mark.