Dirty plugs - replaced with Iridiums today

[BigTed]

I received a set of Iridiums from the UK for Little Miss STealthy a few weeks ago and decided to put them in today….

The original OEMs were replaced at 24,000km when I had it serviced with standard NGKs - so these have about 22,000km on them. She’s been taking a while to wake up in the morning of late – still starting, but just running a little rough for the first 30 seconds or so. I also noticed that a quick blip of the throttle would often create a little back-fire.

So, wifey is out, kids are out, dogs are asleep, and there’s nothing on the telly…

I initially assumed it would be easy – just take off the small access panels and bingo-bango. Nope. Not that easy – one plug lead on each side is difficult to clear the faring. Back to OzSToc and ST-Owners to browse. I then returned, removed one bolt holding the faring each side immediately above the panels, then a little twisting, pressure on the plastic, and out they came.

Here are what the old plugs looked like, numbered 4 down to 1 from left to right, with a new Iridium on the end:

If you look closely, you can see a little “dag” on the tip of #3, along with some significant discolouration of the ceramic stem – I assume that might have been causing the sluggishness on startup. She’s a beaut now though.

[Rodd]

I had the plugs out of my ST1100 yesterday and the gaps and colour of the plugs were still good. I'll be fitting the iridiums soon I hope and then go through the carb balance, etc at the same time.

[TAZZIEBAZ]

Looking at that little dag I'd say that would definitely have been the problem. I've got 24,000+ kls on mine at the moment but the motors running fine so don't really see a need to change them. I sort of figure, "if it ain't broke, don't fix it", of course if it started running rough then I'd certainly do something about it. 

[Down Under]

Iridium plugs are hard to beat for cold starts and extended life.

Cheers,

Tony

[BigTed]

I forgot to ask... is the blackening to be expected on the ST1300?
The plugs I extracted had about 3,000km of ULP-95 (mixed brands), then nothing but BP 98RON since (for the last 19,000km).

[saaz]

The bike might run slightly richer on 98? as it is a denser fuel than the recommended 95, but the EFI should compensate a bit for that.

[Biggles]

Just use pure clean 91.  It doesn't ping and costs 10 cents per litre less.  Use BP if you insist, but I generally use Shell, the one with the second worst reputation after the independents.