Rate these spark plugs please!

PondTunes

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Spoke with a mechanic about going through an engine on a pontoon we are looking at buying.

This is on a 90hp 4 stroke Honda and the shop wanted $250 per carb to clean them... so I figured I would undertake that myself as I have a manual and have cleaned plenty of carbs over the years.

He also mentioned to make sure the plugs have no rust on them, the top two #1 and #2 did have some junk on them while 3/4 looked as expected. Any tips or suggestions from those who work on outboards way more than me?

Plugs from left to right #4 #3 #2 #1 with number four being the bottom cylinder.
 

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Sea Rider

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To charge $ 250 to clean each carb is a out of this world price, shop owner is insane, no wonder his bussiness won't last long. How many run hours does spark plug set have, plugs looks fouled near even to me.

Happy Boating
 

robert graham

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Harbor Freight Spark Plug Sandblaster for $15 or 4 new plugs for $40....they just need to have the carbon blown off....
 

PondTunes

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I don't know the hours on this set of plugs or even the engine. Is there a way to pull that info with no hour meter? Maybe the CDi/computer? Engine is a 2003 model.
 

fhhuber

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Plugs look like the engine has been running slightly rich a long time...
 

gm280

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If you can clean them up and verify there is no electrode erosion, check the gap and reinstall them. I use a wire brush on my grinder setup and then compressed air to blow everything out of them. Then check gap and install them again.

They do look like they have been running rick. But that easily could be not running for a lengthy long time as well. JMHO
 

PondTunes

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Okay, we pulled the intake manifold and cleaned the carbs and flushed the fuel lines with fresh gasoline. The manifold gasket didn't survive so I will try to track down one of those in the morning. I'll probably just pick up a new set of plugs as well just so everything is fresh.
 

Sea Rider

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Check with Honda if run hours can be checked with tach, will be convenient to know that. Better replace all 4 plugs for new ones. Check time & carb advance, valve lash, probably slight out of adjustments. Will need a Service Manual for those ones or a techie that knows how to check/adjust those.

Happy Boating
 

Schtoopid

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1st 2 are too rich, (not much), 3rd one was dropped? 4th one looks just right.
 

fhhuber

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Note: I'd rather be slightly rich on the fuel-air than lean at all...

Rich fouls plugs (slowly if you are just a little rich)
Lean overheats.

Rich is cheaper.
 

bruceb58

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You need to pull your plugs and do a read after a high speed run. Looking at plugs after the engine has idled at all is almost worthless.
 

ahicks

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I'd put a new set of plugs in to eliminate worry.

On the carbs, I just went through the ones on an engine I bought recently. I was quoted 700...... I think these guys are sending them out to a specialist, then doubling what they are charged.

Honda carbs tend to run lean, causing sometimes lumpy idle/miss and a hesitation when accelerated quickly. Those plugs look like they might be running in an engine where somebody over compensated a little. Engine could have spent a lot of time idling as well, without ever being cleared out.

Something I can pass on to a first timer on this carb (from lessons learned when I did mine), there's a jet in the bottom of that brass tube (that runs from top to bottom) that's so small and difficult to clean, many just replace them. If it's plugged, you're going to have a lean idle issue bad enough where that cylinder is going to drop right off line on the idle. Ask me how I know about that...... 1 of the carbs I did had to be redone. I finally found something small enough and stiff enough to clean them. It was 1 wire from one of those 99 cent wire brushes you get from Harbor Freight. Consider there is crud build up on the walls of that tube that may plug that jet AGAIN if you aren't careful when cleaning. I had to pull mine down a second time because of that.

Note the older Honda Goldwing carbs have one of those tiny idle jets as well. If you've ever done a set of those, you're good to go with these carbs. Just take your time!
 

PondTunes

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I'd put a new set of plugs in to eliminate worry.

On the carbs, I just went through the ones on an engine I bought recently. I was quoted 700...... I think these guys are sending them out to a specialist, then doubling what they are charged.

Honda carbs tend to run lean, causing sometimes lumpy idle/miss and a hesitation when accelerated quickly. Those plugs look like they might be running in an engine where somebody over compensated a little. Engine could have spent a lot of time idling as well, without ever being cleared out.

Something I can pass on to a first timer on this carb (from lessons learned when I did mine), there's a jet in the bottom of that brass tube (that runs from top to bottom) that's so small and difficult to clean, many just replace them. If it's plugged, you're going to have a lean idle issue bad enough where that cylinder is going to drop right off line on the idle. Ask me how I know about that...... 1 of the carbs I did had to be redone. I finally found something small enough and stiff enough to clean them. It was 1 wire from one of those 99 cent wire brushes you get from Harbor Freight. Consider there is crud build up on the walls of that tube that may plug that jet AGAIN if you aren't careful when cleaning. I had to pull mine down a second time because of that.

Note the older Honda Goldwing carbs have one of those tiny idle jets as well. If you've ever done a set of those, you're good to go with these carbs. Just take your time!

Hmmm! So the needle that runs through the main jet has a passageway through it? As in it's hollow? If so I'll definitely have to pull those again. We tried like crazy to clean that in case it was hollow and finally deduced that it was solid. Were we wrong? It had sets of holes in the top and bottom which were cleaned but we never got anything through the length of the needle.
 

ahicks

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Hmmm! So the needle that runs through the main jet has a passageway through it? As in it's hollow? If so I'll definitely have to pull those again. We tried like crazy to clean that in case it was hollow and finally deduced that it was solid. Were we wrong? It had sets of holes in the top and bottom which were cleaned but we never got anything through the length of the needle.


Yes, jet located in the bottom of #18 in this diagram. About 3/8"-1/2" up from the bottom.
http://www.iboats.com/Carburetor/dm/...iew_id.1327487

The jet in that tube couldn't be in a worse location. If you check it out, there's a little pool of gas left after draining the carb. That pool contains just enough fuel to submerse this jet - nearly guaranteeing it will be plugged as the remaining fuel evaporates.

Really tiny jet. Think along the terms of the size of a human hair. Don't force anything bigger through it! The bristle from one of those small stainless steel wire brushes, 1 of them, is about right.

I pull one from a brush with a pair of vice grips and just leave it in the vice grips so I don't drop or loose it.
 

PondTunes

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Okay so pulled the carbs again and cleaned them all and she ran good on the muffs, we took it to the lake today and it did quite well. Although it does seem to have a high speed miss. On most carbs I'd look at the needles / main jet for this issue. Another mechanic cautioned me that the needle was prone to developing cracks would a crack in the needle cause a his speed miss or a miss at idle / low throttle?
 

PondTunes

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jmho here,
seems like an ignition issue

Suggestions? I know we're getting spark on all four and it idles and runs well at low - mid throttle. New plugs do you think it could be breaking down on one of the coil packs at higher rpm?
 

Jcris

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I'm not familiar with outboards enough to say. I have a 4.3 I/O Mercruiser. I'm sure you Googled "coil pack testing"? Did you do a high speed run and then inspect the plugs?
 

ahicks

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I've never seen or heard of a cracked needle. Possibly there was a misunderstanding there. Though I haven't seen one, I have heard of the potential for that same part, the one containing the idle jet (#18 mentioned earlier) cracking on occasion, though I'm not sure if that might lead to a high speed miss.

I wonder if you might be starving for fuel? Is there a chance you can get to the primer bulb safely while the engine is acting up? If so, check to make sure it isn't collapsed, and if not, try pumping it to increase the fuel pressure to see what happens. Thinking some kind of restriction or possibly one of the fuel pumps isn't up to snuff. This assuming you're sure the high speed jets are clean in the carbs.
 
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