Hey all,
I have 19K miles on my 2007 14, I recently bought some spark plugs and was not looking forward to stripping the bike down to change them. It occurred to me that perhaps there would be some efficiency in doing it at the 25K mark when the valve check/adjustment is required, any thoughts? Thanks.

Chris

You can wait that long if you want. Mine were working fine at 44k miles and when I replaced them, I didn't notice any change. hagrid made ultra closeup macro photos of my plugs that revealed some globular deposits on the electrodes. IDK if that is to be expected only from old plugs or if it is something that starts happening from day one but it is probably best to get such crusty old plugs out before a large chunk breaks off and goes up and down your cylinder a few times. My good pal hagrid sent me a set of new plugs and I intend to install them at the normal interval next time.

COOL SPARK PLUG PICS HERE

I think I see those little balls on all of the plugs. The closer views show that the tang that bends over the electrode is concave as though it has eroded more at the center directly above the electrode. This makes sense since there would not be a single path the spark would jump over the life of the plug. As the path of least resistance wore away, a new path wherever the gap was smallest would be established. Over time, these new gaps would occur in a radial fashion burning away the various points that the spark was jumping to from the electrode. I guess that's why we see a uniformly dished out surface on the tang. The center electrode does not look like it is shaped all that much different than the brand new electrode so I don't believe it erodes much but it sure seems to collect globs of something around it.
Britanica:
Cuprous sulfide occurs in the form of black powder or lumps and is found as the mineral chalcocite. Large quantities of the compound are obtained by heating cupric sulfide (CuS) in a stream of hydrogen. Cuprous sulfide is insoluble in water but soluble in ammonium hydroxide and nitric acid. Its applications include use in solar cells, luminous paints, electrodes, and certain varieties of solid lubricants.
So we have balls of something (be they a copper/sulfur compound or just plain steel that melted off the tang) forming on the plug. Hub has seen them stuck on the top of his piston. I guess I don't need to think too hard about why it's important to change spark plugs regularly. There is no way to stop these little balls from forming and bouncing over the cylinder walls a few times but having them clinging precariously to a spark plug and waiting to break off is asking for unnecessary engine wear. The busa is at 10k. Time to change plugs on her too before she goes back into service. Oil, filters, air filters, plugs... it's all the same story, they'll last for ever you want them to but it's no good for the engine.

I would change them at the normal interval or sooner. It can't hurt and it might help avoid unnecessary engine wear.

Every 7,500 miles, the plugs are to be change out = Mostly for peak performance intervals. That's more like a plasma spark across a gap. That's also; 'for every action/equal and opposite' = arc at 2 points. These are very small particles being etched away on every spark. E finds the shortest path and at its sharpest point. That's why the tip of the iridium wire is sharp all the way around, the flattened side electrode has the end cut sharp.

1. Once the edge is rounded after thousands of miles of molecules being melted off the material [with each spark remember], the spark now hunts for a sharp edge = Misfire.
2. Removing the plug early is a good thing. One of the problems is metal bonding of the steel plug to the aluminum threads in the head. But today's metallurgy and coatings help. You are handcuffed to mag, which is heat, which now becomes a chemical reaction, remember.
3. This is a high performance engine. Novices line up at the tree with used plugs. Pro's change out plugs... a lot. They still read a plug or see the only x-ray of what is happening inside the chamber, like fuel trim/det/etc.
4, Yes you could get away with it until the valve service.

* Last updated by: Hub on 3/16/2017 @ 10:55 AM *

Valve Adj. Efficiency:

1. Book setting ~ Best OL performance. Setting the lash between high and low ranges is IDEAL BLUEPRINT.
2. Tight valve ~ Best top end performance. Setting the lash at the low range; HAPPENS SOONER.
3. Loose valve ~ Best low end torque. Setting the last at the widest gap; OPENS LATE.

A. Blueprint ~ Best OL performance.
B. Tight ~ Best way to burn a valve.
C. Loose ~ Best way to add more carbon to a valve.

I. Blueprint ~ Best heat-to-cool efficiency.
II. Tight ~ Less seat time to transfer heat so it cracks; causing empty spots or 'pie cuts' to break off.
III. Loose ~ Cools the valve too much so carbon builds rather than cooks it off.

Tight ~ Exhaust opens sooner so power is lost as the explosion pushes down on the piston could have lasted longer.
Loose ~ Exhaust remains closed longer so the diminishing return is exploited somewhat.
Book ~ Exhaust is set to formula as it trickles down to incremental movements between those tiny gaps.

* Last updated by: Hub on 3/17/2017 @ 9:21 AM *

Wow 14k miles on a 14. Encouraging news to say the least. Currently have 6-7k on mine. Good to know I have plenty to go!

Thanks all! Wills, actually 19K miles, I bought with 4K two years ago and because the weather here is so nice!