Spark plug gap

[WilCo]

Boat ran rough mid-rpm last time out so I changed the spark plugs. I found it odd that the ones installed were gapped at about .4 when the gap is supposed to be .8-.9. I gapped the new ones correctly (I hope). Anyone else notice this on spark plug change. My engine was replaced by the dealer (timing chain) and I’m guessing g they just transferred my old plugs to the new one, but it’s even worse (in my opinion) if they installed new ones without properly gapping them.

 

[tdonoughue]

Actually, you probably had the wrong plugs installed. Plug should be an LFR6A, not an LFR6A-11. The difference is the gapping. There should be no need to gap the plugs on install (and some speculation that doing so will weaken the electrode and put you at risk of an engine problem...).

 

[WilCo]

Genius right there. Exact problem. And that’s the same ones autozone sold me when I told them LFR6A. Oh well, properly gapped now.

 

[tdonoughue]

Yes, AutoZone does not generally stock the right ones. Only the wrong ones...

 

[haknslash]

Next time order them from partzilla and save $$ and you'll get the right ones.

 

[Zeusmotorworks]

https://jetboaters.net/threads/210-fsh-tr-1-spark-plug-gap-need-for-tr-1-specific-info.23535/

Post #5 on "pre-gapped" plugs...

 

[scokill]

Amazon.com: NGK Spark Plug LFR6A 6668 (Pack of 4) Watercraft FX FZR FZS VX VXR VXS Reach 26.5mm Hex Size 16mm Gap 0.9mm Resistor Value 5K Ohm: Gateway Next day delivery for me for free.

 

[WilCo]

Thanks everyone. I re-gapped the AutoZone ones and boat ran fine today. I may order a spare set of the factory gapped plugs, but as Zeusmotorworks mentions, they don't always have the right gap anyway.

I'm more perplexed as to why the dealer installed plugs that weren't gapped correctly when they replaced my engine.