Restored performance with spark plug change.

[FSH 210 Sport]

So recently read about problems from rough running through regaining hundreds of rpm’s by putting in a new set of plugs. Also, read one post the other day about a guy who put in a new set of plugs, had decreased performance, pulled the plugs and gapped them then everything was great.

I had bought 10 plugs off of Amazon. One box plus the two singles all needed to be gapped. One box was set perfect at .028”.

Question to those who’ve had success by changing plugs, did you check the gap on the old plugs when you pulled them out?

I just put in a new set of plugs today, all gapped at .028”. I had lost about 250-300 rpm’s on the plugs that have 110 hours on them. I then checked all six used plugs’ gap. Two were still at .028” where I had set them, two were almost .035”, the other two were right around .032”. Factory spec is .028” - .031”, not much of a spread. All had the same burn characteristics, just a bit off white towards the tip, and just a hint of gold further down.

We shall see what happens next time out.

 

[biffdotorg]

I was starting to lose some RPM's this season, so I did the math and realized I have not touched my plugs in a couple seasons. I am all for inspection, but not changing them unless I see a performance decrease.

When I pulled them, I found that most of these plugs were finger tight. I would have almost guessed that the crush washer was not compressed. I did check gap on all plugs, and they were at the .035 spec that they come from NGK. I actually think I gapped them to .033, since my manual was saying .031-.035. (this is the 1.8ltr gap, so yours is different)



The new plugs were all .034-.035 out of the box and I put them in. I am gonna run it this weekend and see. Otherwise, I may just pull them all and gap them tighter to .033. But performance will be the sign. Burn on the old plugs was even across all cylinders. So I'm happy with that.

Good luck!

 

[Babin Farms]

When I pulled them, I found that most of these plugs were finger tight.

I have had the same thing the last 2 seasons with my plugs. It doesn't take hardly anything to break them loose and I know that they were good-n-tight when installed. Guess I'd rather have that than a seized one.

 

[FSH 210 Sport]

Thanks for the responses !

I went out for a day on the water with full fuel and I did see an increase of about 100 rpm’s. I’m going to chalk up the rpm loss to an increase in density altitude… It appears that my repitched (high altitude) impellers are spot on as far as I’m concerned in achieving the best compromise between performance / highest rpm’s and keeping the impellers as loaded as possible to keep the engines off the rev limiters.

I had recently took my boat to get valve clearances checked, the mechanic had pulled the plugs to do this work, so no way for me to know how tight the plugs were after 110 hrs of use. ..the plugs didn’t seem very tight when I pulled them though. I used a torque wrench set at 9 ftlbs when I installed the new plugs, the manual specs 9.5ftlbs, I’ll be changing the oil before too long and I’ll recheck the plug tightness at that time.

Thanks again for the posts!