70,000 mi. on 08 FLHT checked them at 50,000, looked good. Guess I'll replace them at 80,000 or so. haven't noticed any change in performance or gas mileage yet. Probley just throw a set in the saddlebags till I do.

 

I change plugs when I feel I need to fiddle with something, put a dab of anti seize on and torque them to 18 ft lbs. On a properly tuned bike they should last probably 50,000 miles.

 

Its because the copper is a high temp formula up to 1200-1800 degrees, so it stays in place in high heat areas.

 

Service Manual for My 08UC says to replace Them every 20K and inspect them every 10K, which is what I do. 35K on the bike now, got 5K left before replacement. No problems.

 

Just looked in my 2010 manual and it is replace at 20k for 2010

 

Today I have the need to throw a couple of posts out, so here goes another. Now keep in mind not to listen or pay close attention to anything I post, because most would say I'm crazy, and most of the time I wouldn't disagree.

Spark plugs, the people changing theirs every 5k, just like doing it, or have problems that need to be addressed on their bikes. There is absolutely no reason a spark plug on a newer bike (20yrs or less) should not go 20k without any problems. Granted there are a few exceptions, but most of these would be known by the owner, and there would be an explanation.

The book as mentioned by another post, suggests 20k replacement, and I see no reason to carry a spark plug around on your bike (just in case) unless your riding a 2 stroke or a motor with a major problem. I mean I would like to hear from a couple of the people who say they carry them on their bikes, when was it needed, what bike, and why?

For the anti-sieze, the book also calls for silver here, and I know of no anti-seize that is aluminum ( it's possible there is some but I have never seen or heard of it). I only know of silver, copper, and nickel. As far as copper being higher temp, slightly, but not enough to make much difference, I would guess the majority of the time these are changed due to galvanization. I only say this because (these are approximations) silver is around 1600*, copper 1800* and nickel 2400*. So if it were for high temps the nickel would be the best choice. Plus your motor is never going to get close to any of these temps.

Conclusion, service manuals for several years now have recommended checking the plugs about every 5k and replacing them when needed or every 20k. High mileage drivers should be perfectly fine checking every 10k and replacing @ 20k. The Manuals also call for silver anti-sieze and not copper, but that's from the manual, not me or MMI.

 

Regular plugs under normal use are good for at least 20k miles and probably a lot more. You can change them every two hundred miles if you want, but it is not necessary.

 

Copper and Aluminum and Graphite. All metals....don't want them in the combustion chamber.
(go to the neverseeze web page...they may have silver and nickel...I've never used them)
Found nickel on permatex......it is copper free. Nickel is used at nuclear reactor sights...neverseeze has it also. I believe the silver you are referring to is really, mostly aluminum.

 

Just to follow up......champion spark plug co. recommends not using anti sieze....plus they recommend after finger tight, tighten 1/4 to 5/8 turn. No torque specs....just 1/4 to 5/8 turn more after finger tight. They say that the threads are coated with something when manufactured.
(I knew I learned this years ago....just a refresher)

 

Regarding antisieze,found this.......
http://www.ngkplugpro.ca/content/con...SparkPlugs.pdf