Analyzing spark plugs

[TonyNoriega]

I bought this boat/motor 6 wks ago and the previous owner said he hadn't changed the plugs in the 3 years he used it, so I'm going to change them tomorrow. The engine is a 2001 Yamaha 200hpdi.

What should I look for when I pull the plugs? By the way, I also told he he never used Ringfree or anything similar.....would carbon buildup be apparent from inspecting the plugs?

Thanks!

 

[Scout Sport Fish]

Re: Analyzing spark plugs

Carbon build up is very aparent when you look at the plugs. Thick, black, dust, somtimes oily if its a 2 stroke.

 

[TonyNoriega]

Re: Analyzing spark plugs

And carbon buildup is precisely what I found.....I'll be doing a decarbonization procedure this morning with Seafoam.