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Discussion Starter #1
Our local dealer states they sold 376 of our NGK plugs last year. And already 43 this january.

I got to thinking and all the Vulcan 900's in my sig needed plugs, and the one with 1500 miles fouled out as a result of us starting in "dewpoint" conditions.

When looking at these NGK plugs, they appear to get fouled way up inside with the only solution becoming to cook them on a gas stove for 20 minutes, and regap to 0.030 instead of factory 0.032 - 0.036.

Any idea why these eat up plugs so much? My stratoliner has original plugs with 9k on them.
 

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Same here. I get about 15000+ miles out of mine. I do clean them one or twice during that time with a a stainless steel brush, check the gap. Getting ready to change out my second set, near 40000miles. Both sets ngk's.

I operate in a high moisture area, rarely below 85%, cool most of the year.
 

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1. I do not recommend using a metallic brush when cleaning plugs. It "can sometimes" leave a metal trace on the insulator which provides an intermittent short to ground.
2. Plug evaluations have to be done on a case by case basis as the fouling list is a mile long.
3. Many folks change like new plugs for new when all that really does is risk a broken plug, stripped threads, etc.
4. The "dewpoint" issue is one I have never heard and makes no sense to me.
 

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1. I do not recommend using a metallic brush when cleaning plugs. It "can sometimes" leave a metal trace on the insulator which provides an intermittent short to ground.
2. Plug evaluations have to be done on a case by case basis as the fouling list is a mile long.
3. Many folks change like new plugs for new when all that really does is risk a broken plug, stripped threads, etc.
4. The "dewpoint" issue is one I have never heard and makes no sense to me.
The thing about number 3 is that you don't really know they're like new until you get them out. It's a catch 22.
 

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My original plugs looked great at 15K miles, bike ran well never a misfire etc.. I replaced them with Iridium plugs (no good reason), not sure why Kawi recommends 7.5k mile change. I could have left the original plugs in longer but decided it was a good time to change them when I was doing the valve clearance check. I run regular gas and have had no signs of fouling on the plugs.

WB
 

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If everything is in order, plugs will go thousands upon thousands of miles before a change is needed with no need for an inspection every 5000 miles, but it is up to you. If plugs need attention, they will usually let you know.

I have a vehicle that requires the intake manifold to be pulled to access the rear plugs, so that is something I will not be doing until absolutely necessary! (120,000 miles)
 

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If everything is in order, plugs will go thousands upon thousands of miles before a change is needed with no need for an inspection every 5000 miles, but it is up to you. If plugs need attention, they will usually let you know.

I have a vehicle that requires the intake manifold to be pulled to access the rear plugs, so that is something I will not be doing until absolutely necessary! (120,000 miles)
Kind of what i was thinking when it comes to spark plugs "if it ain't broke, don't fix it" they will let you know if there is an issue, run rough, misfire etc..

For what its worth, a friend of mine has a victory and the shop manual says replace at 30K miles.

WB
 

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Per the Owner's Manual chart I pulled the spark plugs on my 900 at 7,500 miles and had already bought the replacements. It was a complete waste of time and money as the OEM plugs looked like new and the gaps were per spec. No fouling whatsoever.

Have never heard of a "dewpoint" starting and fouling situation issue for motorcycles. Maybe back in the car "Dark Ages" when spark plug wiring would sometimes short out when damp or wet and so kill the spark . . .
 

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Discussion Starter #11
Being these bikes were aquired 2nd hand, maybe there were other factors that we don;t know about. They were all carbon fouled, but the funny part is when the new ones are installed they are running super clean like the ones shown in the post. The high dewpoint was becuase it got down to 20 degrees, and a storm came in and raised it to 50. The whole bike was soaked, actually dripping even though it was in the garage.
 

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Could it depend on the quality of gas and if you run fuel system cleaners?
 

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I've got 72,000 miles on my 900. Ride it in all kinds of weather. Rain and low temperatures. Pulled the plugs for inspection about three times. They are never fouled and gap was always close enough to pass. Planning to run the original plugs another 72k.
 

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Have never heard of a "dewpoint" starting and fouling situation issue for motorcycles. Maybe back in the car "Dark Ages" when spark plug wiring would sometimes short out when damp or wet and so kill the spark . . .
I had a breaker points & distributor '64 Ford truck that would do that sometimes, at least I think that was what was happening. The plug wires were old and getting cracked porous insulation that would take up water. I replaced the wires and it never happened again.

But if an engine (or an iced tea glass or anything else) is cooler than ambient temp it will indeed pull moisture out of the air.
 
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