I have 2 questions here.
When I bought my boat which was used the guy who had it before me was running Champion RC12YC plugs in it. The last 2 years I've been using NGK BKR6EKU plugs. Is one of these better then the other?
My second question is do dirty plugs cause motors not to perform as well?
I looked at my plugs today and there pretty dirty and I've lost about 400-500 rpms and wondering if this is related to the plugs being bad or If I have something else wrong.
Thanks.
Bad, dirty or fouled plugs could be the cause of a rpm loss, the only way to tell for sure is to change them and run it and see what happens.. I have personally only run the NGK plugs in my yamahas as that is what they came with and also what Hydro-tec installs.. From what I have heard, the champion plugs are made to have the electrode fail before burning a hole in the piston, which would work well in a nitrous or supercharged, or turbo application (the theroy we followed when building drag car or really hot street car engines).. Now after that side bar, back to your original deal, if you are doing alot of idling around, and low rpm running with your yamaha, maybe consider going to a 1 step hotter plug, a #5 NGK, as this will help to burn off the extra oil at an idle.. A hotter plug will put the electrode further into the combustion chamber causing it to be a little closer to the flame front and in the heat of combustion. Hope this helps, sorry it seems that I rambled on.. Good luck..
Thanks for the reply and you explained everything really well. I do idle around a lot do to all the no wake area's. I will stick with the NGK plugs, but I'm not sure If I should go to the hotter plug or not. Does this cause any problems with the motors later down the road?
I am going to buy new plugs to see If it fixes the rpm problem, I just want to make sure I get the best and right ones first.
One other thing I just thought. I've never had any problems with my plugs until after this winter when I had the new oil pump installed. I don't know If that has anything to do with the plugs fouling or not.
Thanks again.
Ahhh, I would say YES the new oil pump is the cause.. They are dumping a LOT more oil in to avoid any bearing issues. And the idling around coupled with the new oil pump would help to load it up a bit... There will be no adverse affect from running the hotter plugs if the engine is stock, if you've gotten any mods such as Hydro-tecs rec heads you will want to stay with the colder plug, doing just reeds won't change the compression any so you could run the hotter plug with them.. I'd be willing to bet if you put the NGK #5's in your problem would go away... It is also possible that your oil pump rod is not adjusted properly, may want to have that checked too...
Thanks again dentguy for the help.
I'm going to order the new hotter plugs and see how things go. If they foul I'll take my boat back to the shop and have them adjust the oil pump.
Is BKR5EKU the plugs I want? My old ones are BKR6EKU.
I do believe that is the number!! Keep us posted on the results!!
Put the new plugs in. (#5's) Probably only ran the motor for 30min total yesterday and I checked the plugs today to see how they looked. They were black at the tips and had wet oil on them. They looked like they were used all year. I'm going to take my boat back to the dealer this week and have them adjust the oil pump.
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