Gapless plugs on my 200 HP, is there a reason? Is this the plug to use?

[sbklf]

I just purchased this boat/motor (1998 200 HP Merc carbeurated) and it has those plugs in it that are flat on the end less the little arm over the electrode. When I saw them it came to mind that the previous owner might have installed them to overcome a fouling issue maybe?

I will change the plugs, is this the style plug that this motor uses?

I ran it yesterday and it ran OK wide open throttle but idled a little rough with an occasional backfire.

 

[Really Old Guy]

Re: Gapless plugs on my 200 HP, is there a reason? Is this the plug to use?

That's right. They actually work well and alow better head space.
They do break down, so if unknown age replace them.