2004 Johnson 115 - Champion or NGK Plugs?

[riptide09]

2004 Johnson 115HP 2 stroke Carburetor. The motor came from the factory with Champion QL78YC plugs and that is what I have always used. I need to change the plugs and I have a friend who is a mechanic and he swears by NGK plugs. I am tempted to stay with Champion because I have never had any issues with them however I am open minded.

I spoke with 2 mechanics at 2 different dealers that I have dealt with. When I asked them about plugs the first one said, Champion all the way. Came from the factory that way and stick with them. The second said he had used both. He said he thought the Champions worked better. I should have asked which NGK he used but I wasn't thinking.

I pulled up a few spark cross reference pages and from what I can determine I want to use an NGK BPZ8HS-10

I wouldn't really spend much time thinking about this and go with the Champions however the guy who is telling me to use NGK is the mechanic for my cars. He is one of the best and honest mechanics I have ever had and he works on a of of boats also.

 

[racerone]

Sparkplugs are a pretty simple item.-----NGK of the correct heat range will work just fine.

 

[ronward]

I certainly can't dispute anything racerone advises but I do know that some motors will do fine with the change, some motors don't. Try the NGK if you want to. If the motor doesn't run as well as it does with the Champions then just switch back. I tried both in mine and I think the Champions worked better.

 

[Vic.S]

Its important to recognise that inductively suppressed plugs should be used in OMC engines with VRO or OMS systems ,

The Champion "Q" series are inductively suppressed and QL78YC are the recommended plugs for the engine in question.

Many if not most makes of outboard use NGK plugs . They are usually the plug of choice outside the USA.
The "Z" series NGK plugs are inductively suppressed

Do not use resistor plugs ie those with an"R" in the number

I found NGK BPZ7HS-10 and BPZ8HS-10 as equivalents to QL78YC.
On the NGK heat scale 7 is a grade hotter than 8 ....You may have to experiment to discover which best suits your engine BPZ7HS-10 or BPZ8HS-10 ... The latter may be too cool.

-10 on the NGK number indicates that they are supplied gapped at 1.0mm. You will have to re-gap them to 0.030" (between 0.7 and 0.8mm)

 

[Vic.S]

Sparkplugs are a pretty simple item.-----NGK of the correct heat range will work just fine.

Very far from the truth.

Every letter and number symbol in a sparkplug code has a specific meaning defining the main features of the plug design such as thread diameter, reach, hexagon size , suppression type, height, type of seat, firing end design , electrode type and material as well as the heat range.

The effects of fitting a plug of the wrong design, even if of the correct heat rating, could range from poor performance to serious mechanical damage.

Explanation of the codes for Denso, NGK and Champion plugs here.

http://spark-plugs.co.uk/index.php/contents/display/25/technical.contents.symbols

See elsewhere for the codes used by other plug manufacturers

 

[riptide09]

Thanks for all the feedback. I am going to stick with my original thoughts which is stay with the Champions. The motor runs fine, no missing, no hesitation and hits redline with no problems. Champions have treated me good however I am always open to listen to some alternative views.

 

[dazk14]

Thanks for all the feedback. I am going to stick with my original thoughts which is stay with the Champions. The motor runs fine, no missing, no hesitation and hits redline with no problems. Champions have treated me good however I am always open to listen to some alternative views.

You've made a wise decision, You also gave a perfect example of the problem switching brands...it crossed over to 2 very different heat ranges.

We'll sometimes use NGK in a champion recommended engine - but we've got the testing data to back it!

Oh, and that 1mm gap does NOT work well at .030...the geometry gets distorted.