Spark Plugs

[Alba]

Just changed the spark plugs, old ones had carbon deposit, gap was still within spec, therefore why change?

How does a spark plug become dud

[StumpyFingers]

The spark plug is like a mini arc welding rod.
As it arcs the surfaces of the plug vaporize, Add to that the fact that it is in a high pressure high heat environment.
This has a detrimental effect on the plug over time.

[Lumiya]

It's also not just that... the cores continually heat up and expand and then cool down and contract, eventually the cores either break and you get the cylinder hard to start when cold, or the insulator cracks and can drop sections into the piston... Also on resistor plugs the resistance can change altering the engine running

Always best to swap them out every couple of years even if you've not ran them for a lot of milage..

[Mervinh]

also if they are resistor plugs the resistors break down over time usually a short period if my experience is anything to go by, and occasionally iffy batches of plugs get into the market so if you replace a plug and it is worse it is possible the new one is the problem

[Alba]

Always best to swap them out every couple of years even if you've not ran them for a lot of milage..

I tend to replace plugs, filter & oil every 6K. is that too quick for plugs?

[Lumiya]

Depends who you ask, how often you use the bike, whether it used daily or just long trips... In hot/cold weather..

Short frequent trips in cold weather is worse for the thermal shock..

Personally I swap mine round every two years when the bike is active, but when I was a courier it was every 3 months (but I was doing 80K+ a year)