I have searched on "plug reading" but did not find what I was looking for. I have an 06 EG with 6500 miles on it. Stage one with Bub's cross dresser duels, Rush 2.5 muffs, Big sucker and shim carb needle, 46pilot, 2.5 turns on low speed needle. Bike runs good, no smoke, no oil usage. It idles nice and pulls strong.
I pulled the plugs for a plug reading yesterday. Front plug is beautiful, rear plug looks "rich". These plugs have about 2000 miles on them. I put in a fresh set and rode about 30 miles and pulled them. Front plug again looks great, rear plug already has black soot on electrode, porcelin, and ring.
Did a compression check, both cylinders fine and within 3 psi of each other.
I am thinking leaking valve seal. Would oil be shiney on the plug or just black soot? Could I be feeding more fuel into the rear cyl?? If it is a valve seal will MOCO fix it under warrenty even thought the bike runs good??

What do you guys think?

Thanks for your time,
Doug

 

It is actually a good thing the rear cyl is a tad rich because of less cooling.If the front looks Okay,there really isn't much you can do with both cylinders sharing the same plenum.Your only course of action is a little hotter plug in rear.I would talk to a plug manufactor,or any of the after market Harley Hot Rodders.Good Luck

 

If it is a rich condition, and not oil then it is VERY rich. Something is not right.
Any other ideas?

Thanks,
Doug

 

The bike is injected.and is the plug sooty black or just darker than the front?

 

Better rich than lean,especially on the rear cyl.I would ck the frt cyl for a intake leak.

 

Its a carb. I understand that rich is better than lean, but I am wondering if it is oil, not fuel soot? How can I tell?

The intake leak is a possibility. I recently had the gas tank off. I noticed the intake manifold had alot of "black grime" on it where the intake meets the front cyl. Rear cyl to intake was clean. Hmmmmmm, thanks GTK. I will check that intake,

Thank you for all your replies,

Doug

 

I am taking the plugs to my local dealer. Maby they have an idea.

Doug

 

How do you get an 06 FLHTC,(or whatever model), without the "I" for fuel injection???

 

http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html
Good Chart

 

Today,with the urine we are running you have to go for slight color at the base of the porcelin.It is really hard to do,without good light.As far as I am concerned,without a trip to a shop for either a dyno pull or just plug into a reader to see what is what.If the bike seems to be running acceptable to you and not fouling plugs or whatever just enjoy it.It's a good thing to be concerned,you will enjoy a lot of good years in the saddle.