Good advise generally for the Iridium spark plugs. They come gaped at 32 thousandths. But the gap can be adjusted. We've found that a gap of 38-40 works best. But you must be very careful when adjusting Iridium spark plugs. You cannot put any pressure on the center electrode. They are extremely hard and extremely brittle. You need a gap tool that will move the grounding electrode without touching the center electrode. like the one pictured below. You can use a wire or flat gauge to check gap as this will not put enough pressure on the center electrode to do any damage.
So.....when comparing, do you compare with a stock plug that has that same gap too ?
A wider gap means that a higher spark voltage is needed to jump the gap.
We have found that there is enough spark energy to jump the wider gap when ridden in the manner intended (proper RPM for the conditions, etc.). Most manufactures do not tune spark plugs for best performance. They tune them for reliability in all expected conditions. If you are going to lug your engine or ride in ways that tend to foul the plug, then I would recommend keeping the narrower gap so that your spark plug can overcome these less than ideal conditions.
ACE 1330 Shop Talk
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Originally Posted by irvin48
