Spark plugs

[mini moe]

I'm changing plugs in my 115 mercry 4/sroke and the number on the plug is NGK LFS6A. The number for my motor on a online store is LFS6A11.
Does anyone know what the 11 at the end of the number stands for? Is it the same plug or does the 11 change the specs. on it? Thanks.

mini moe

[wasabi]

Hey moe,

Sorry, don't know the answer to your question. But my Johnson (Suzuki) manual gave me part numbers for several brands. I got my NGK's at the local auto parts place - I think it was Advance? Personally I wouldn't trust any online lookup to recommend a different part number unless I confiremd it was right via my manual or by calling the manufacturer. I think these stores give out a lot of bad plug advice.

[mini moe]

Thanks Waddy, I tried advance and auto zone and they didn't have them. I had to get them from a marine and they cost about $9 bucks apiece. I wish advance had of had them. The 11 on the plug was rubbed out and when I took the second one out it had the 11 on it, so everthing gived. My motor was skipping and cutting out big time and the plugs fixed it fine. The guy that sold me the plugs said that mercry was made by Yamaha. Huh, I didn't know that. He says that a mercry is a Yamaha engine with a mercry cover. He's a mechanic and should know but he drinks a lot too.

[racn35]

I think - I said I THINK - it has to do with the LENGTH maybe in MM ......if you buy a plug thats too LONG your piston may hit the end of the plug and your in deep sh!t then. the 6 I THINK is the FIRE of it on a hit/cold scale - IE:: LFS6 verses a LFS5 ......too much reseach to care,mine just goes to a SUZUKI SHOP- and thats all they do are Suzuki's. But if you want a NGK site heres is a good one -

NGK Spark Plugs (http://store.usavediscountmarine.com/sparkplugs1.html?gclid=CJbCu9vao5UCFQVxFQodfntPZQ)

[hardhead]

google:http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf

[mini moe]

Thanks Jamie and Hardhead, those sites helped. The dudes where I bought my boat said to use mercry gas treatment in every tank. That dang stuff cost $13.50 a bottle and probably wouldn't treat but about 3 tanks full. Hell!!! I could buy a new boat every few years for that price. I was suckered into getting one bottle before I thought it over. I guess I'll use it it my lawnmower, it fowls plugs pretty bad. They say it cuts down on carbon build up. I've also heard that some boat fuel tanks will leak if you use eythenol, because of the kind of resin in the fiberglass tanks and that gas treatment may be bad on that kind of a tank also, I don't really know just guessing. I don't even know if my fiberglass tank is one of the ones that leaks or not, but when I open the battery hatch that leads to the battery and beilge compartment , it has a real strong gas smell. That could be the vent or it could be gas leaking. I may even need a fan for the fumes, some regulations call for it on some model boats.

[FinaddictMike]

My tidbit of advice is this...Never cross reference an NGK plug to another brand because the heat ranges are different. I let a parts guy talk me into some champions and boy was I dissapointed. I ran them one time during a striper trolling day. Plugs kept fouling out, stalling the engine. Found my NGK's at Napa and life was good again. And yes, Yamaha made all the mid-size Mercury 4 strokes. It was in an older Sportfishing magazine.

[mini moe]

Thanks Mike, I'll use only the kind of plug that was in it new. That was a suprise about the Yamaha dudes making Mercury motors. Do you know anything about the gas tanks leaking?