# Spark plugs 4 stroke engine



## Guest (Nov 2, 2018)

Use only what yamaha specs for that motor! The wrong or improperly spec’d plug can create rf under the cowling and screw with the electronics! Just put what the factory says and change every 100 hrs or annually and you’ll not have any spark plug issues. Man them holiday inn express’ are great!


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## No Bait / Lures Only (Apr 10, 2011)

Shoulda known betta, it's not a 2 stroke..


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## Guest (Nov 2, 2018)

No Bait / Lures Only said:


> Shoulda known betta, it's not a 2 stroke..


Even then, I run what the manufacturer calls for unless I’ve hot rodded it! They engineer these things and test them for the best most durable results with what their voltage outputs are for a particular motor. Some hotter than others, some have resistors built in some don’t, some call for irridiums some don’t ect... If ya just stick with what they call for, it works out best! Now if we are gonna talk raising and squaring ports, balanced rotating assemblies, fiber reeds, milled heads, tuner mods, etc... that’s a whole other thread there lol!


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## noeettica (Sep 23, 2007)

Please tell me Non-Resister won't hose up a cdi box ...


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## Guest (Nov 2, 2018)

Depends on what the manufacturer calls for!


noeettica said:


> Please tell me Non-Resister won't hose up a cdi box ...


They call for certain specs for a reason. I can tell ya that the spark plug is really a path to ground for an electrical current generated by charge coils under the flywheel, stored and released in the cdi,then stepped up in the coils...and that path to ground is spec’d for different engineering in the rest of the system so the wrong plugs can cause problems!


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## State fish rob (Jan 25, 2017)

Boatbrains said:


> Depends on what the manufacturer calls for!
> 
> They call for certain specs for a reason. I can tell ya that the spark plug is really a path to ground for an electrical current generated by charge coils under the flywheel, stored and released in the cdi,then stepped up in the coils...and that path to ground is spec’d for different engineering in the rest of the system so the wrong plugs can cause problems!


Damn who knew ? Alwys thought you went hotter to keep up w oil burn rate. Just trickin’. Got my first 4 stroke in june. Love it


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## lemaymiami (Feb 9, 2007)

My E-Tecs have all had iridium plugs (all three of them...). It was explained to me that they were needed to give the 300 hour maintenance cycle that is routine for these motors.... That's also the reason their lower units have fully synthetic lube in a larger gearcase than other manufacturers use... I'll have to have someone explain to me how they're getting a 500 hour maintenance cycle on the new Gen2 motors... and, of course, none of them are four strokes...


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