85' merc 18hp xd ,sparkplug gap?

[newmercman]

I've got a 18hp merc xd that I just bought.It had new plugs in it so after running it a few times I thought to check and see the condition of them.They were good but the gap was noticably different between the two.Whats the proper gap?And do they wear evenly between the two?If not, is that a bad sign in one of the cylinders?And last question! Im starting to have second thoughts about this ethanol blended fuel, should I start burnning premium gas!

 

[bikepro]

Re: 85' merc 18hp xd ,sparkplug gap?

I gap mine at .028 even though OMC said .030 because the gap widens pretty fast .I change my plugs every 75 hours & they're well into the .040+ range. Plugs should always be a caramel color. If the gap has decreased, make sure that you have the right plugs- I've seen people ruin motors by using the wrong plug... As far as fuel goes, I always buy the highest octane pump gas available, non-oxygenated if possible, and add a little sea-foam to keep things clean.

 

[jebeebe]

Re: 85' merc 18hp xd ,sparkplug gap?

I always thought the merc was supposed to run the "fire ring" plug that required no gapping. Having the wrong plug can definenty burn a hole in a piston. I would inquire from a dealer what plug to run...................JErry