How important is the spark plug renewal?

[Rich:-)]

I'm just struggling to understand why bike manufacturers recommend changing the plugs at such short intervals?
(the 650's plugs are every 2 years or 14,500 miles).
Oh and after a couple of months of ownership I've just realised my 2007 has 4 plugs. 

I mean 2 years is joke..., who in their right mind would change a set a plugs that might have only done 6,000 miles or less just because 2 years was up...  (unless to maintain the warranty).

But why at 14,500 miles - I know these engines rev higher than most car engines but on most cars you won't dream of doing the plugs until 4 years or 50k miles, so why is the interval so much shorter for bikes?

Mine aren't due yet btw, I'm just wondering why.

[UK_Vstrom650]

Kerching....!!!!!

(They have to be seen to do more than change the oil...)

[greywolf]

I'll guess since the interval was established before Iridium plugs were used, it was about taking no chances or even to make money for dealers. After that, the paperwork wasn't updated when the plugs were changed to Iridiums. There are plenty questionable statements in the service manuals.

http://www.stromtrooper.com/general-v-strom-discussion/105361-service-manual-errors-questionable-statements.html

[Hugo Magnus]

I had mine 'looked at' at service, they were fine so went back in. If it ain't bust don't fix it.

[Rich:-)]

I would have thought that if a plug starts to go bad it will become obvious - miss firing etc.
Maybe this will be covered up by the twin spark system so 2 plugs in the same cylinder would need to fail before it becomes noticeable?
With all my other bikes I have ignored the spark plug replacement schedule and simply remove, polish and re-gap on a service. This won't happen on the Strom though as plug removal sounds like a pig of a job. It'll wait until the tank is off or the coolant gets changed.

[joderest]

Agree about plug change, any vehicle I get I will put new plugs in, as I would not know how old the one's in there would be, then I would not change them again in ownership, unless a fault occurred.
Regarding checking plugs, on the Wee I do not find it a pain, can do front and rear plug in about 1/2 hour, only one bolt at front and swing rad up, and just one bolt at rear to release tank.
You should do the plugs on a BMW F650GS, now that is a pain.