Hi all;
I have a 2010 FLHTCU with a seized plug in the rear jug. The front one came out without a problem.
When I was trying to remove the plug, I got it to turn about 2 revolutions and it got very stiff. I then tightened it back up and tried to remove it again. I went about 2 1/4 turns and seized both ways.
How bad is this going to be?

 

Hi from the UK and welcome to HDF.

There is no way of knowing! My inclination is suggest running a thread release agent down the threads and leave, say overnight, to see if that helps free things. Alternatively you could call your local dealer to see if they have any suggestions (other than taking in the bike!).

There are two possibilities: one that there is thread damage and a repair will be necessary (hence head off); or the threads are dirty and a careful removal will be fine. Obviously the second is the one to hope for, so it is worth asking around widely for suggestions.

 

See if you can find someone that has a penetrant called "Kroil". If not, try a bit of 'PB Blaster'. Let sit, like has been said. Hope for extreme carbon, and if so, either of these products will creep down the threads.

If that doesn't work, and nobody has another good suggestion, the head will need to come off and an insert installed.

And... everyone needs to remember to NOT overtighten plugs AND under NO circumstances use ANY kind of thread lubricant on a silver colored plug. That silver coating IS a lubricant.

 

Was the motor hot when you tried this?
Yea on the penetrating fluid over night and then like you are doing work it back and forth.
Good Luck let us know.