Curious if this is a symptom of anything? Rear spark plug is all rusted on the outside, bike seems to run fine and that plug is still firing. I blow dry the whole bike after a wash, and it may be ridden in the rain when I have to, but garage parked. Its on a 2010 Ultra Limited. Thanks in advance.

 

Probably gets a lot hotter at the rear cylinder so the basically untreated bare metal surface of the spark plug rusts easier. I would guess the air in your area has more moisture in it.

 

probably just water sitting in the hole-

2.) don't forget to put anti seize on the threads when reinstalling and ALWAYS start the plug by hand or with a piece of fuel line hose stuck over the end. using a socket wrench it's too easy to cross thread which is expensive, use the wrench to snug up after finger tightening

and never crank the motor with the plugs disconnected from the spark plug wires and the plugs grounded to the motor or chassis.

Mike

 

Very common for them to corrode

 

Moisture causes rust...... you can figure how it got to the rear cylinder and not the front
jug. My guess is its water you missed when you blow dry..................hdman

 

I use to have the same situation with outboard motors used in salt water. The outside corrosion never impacted the performance of the plug. Use to clean up the plugs every couple weeks and they worked fine. Also, as already stated, use antiseize on the plug threads and if the plug does not screw in and tighten down by fingers to the gasket, something is wrong with the threads.

 

OK, I just gotta ask, I've seen this a coupla times before, but I really don't understand the reall meaning??

I've done this on my '05 FLHTCI after I did the 95" w/ cams & reworked heads, etc, to be sure I was gettin' oil to the rockers before puttin' them on....had the plugs out of the engine & wires, & cranked it over long enuff to see oil....NEVER had a problem....so what gives????

 

Thanks everyone! Great to know its nothing to worry about!

 

I got a bit of rust build up too, is it something to worry about? What would you do if this was you?



see that rust down there?

 

Replace your plugs more often maybe. Clean it up before replacing the plugs, otherwise it won't stop. I haven't had this issue on my bikes. I do replace mine often with the OEM plugs though.