Replacing plugs on my Yamaha F150 and yamaha says use NGK LFR6A-11 and NGK’s site says NGK LFR5A-11. So NGK reccomends a hotter plug then Yamaha does…. Motor had the 5s in it but have been done in the past but not by me.
Next heat range must not matter? Anyone have input? Have new 5s in hand and about to put them in and im not a big fan of running whats not to spec.
Wouldn’t be the first time a manual was wrong. Same thing on my dads optimax, book said one kind of plug and should be another one. Service tech figured it out from la Cannes in faribault
Read the plugs that are in it now to see if you need a hotter or colder plug, that would be the best way.
Plugs look great i just like to change them every spring.
Just looked around more under the cover of the motor and there is a sticker saying to run the 5s gapped at .044
Weird how Yamahas website says different.
I just ran out to the garage to grab a spec book for Yamaha’s and in print in both books I checked call for the LFR5A-11 gapped at .039~.043″ and that is what I have always put in them. If it looks like the 5s you pulled out are burning fine stick with them. It’s always nice to hear about guys doing preventive maintenance before it causes a problem! 
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Plugs look great i just like to change them every spring.
I used to that every spring too. When I bought a new F115 a couple of years ago the dealer’s tech/mechanic told me to run the factory installed plugs until I noticed any problem.
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Plugs look great i just like to change them every spring.
I used to that every spring too. When I bought a new F115 a couple of years ago the dealer’s tech/mechanic told me to run the factory installed plugs until I noticed any problem.
Im sure I could go several years but its just part of my routine and new to the F150 this year so was curious on the plug type. Plugs, water impeller, water impeller housing gasket, lower unit drain plug screw gaskets, and crankcase drain plug gasket are all an every year deal for me.
Over the top? Yes! But its a cheap piece of mind!
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