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Discussion Starter · #1 ·
08 1800N. I noticed the last few hundred miles of so, more vibration than normal. Also, my mpg dropped slightly. Vibration not in the tires as it goes away with clutch pulled in and coasting. I pulled the plugs and this is what they look like after 8k miles or so. I went ahead and swapped them cause I had a new set laying around and all the vibration is gone and she's feeling peppy and responsive again. What causes the plugs to look so bad so quickly? 16k on the bike. Valves checked at 8k. Cobra powrpro, intake, exhaust. Thank u.
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Iridium plugs are good for 100K.
 

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The SM shows 0.039 - 0.043 inch gap.
I always go to the minimum gap because erosion will make the gap larger.
The spark plugs are in series, total gap would be 0.078" - 0.086"
I have never clipped any SP wires.
You can measure SP cap to SP cap, 33k to 36k ohms resistance.
The major resistance is the HV Ignition coil.
A 500 ohm resistor in the SP cap plus a 5k resistor in the SP.
Product Specifications:
  • Shell
  • Thread Diameter14mm
  • Thread Pitch1.25mm
  • Seat TypeGasket
  • Reach19mm (3/4")
  • Hex Size5/8" (16mm)
  • Terminal TypeSolid
  • Overall HeightISO
  • Gap.043" (1.1mm)

  • Center Electrode
  • MaterialIridium
  • TypeFine Wire
  • Size0.6mm
  • ProjectionProjected

  • Ground Electrode
  • MaterialPlatinum
  • TypeStandard
  • ShapeTaper Cut

  • Specifications
  • ResistorYes
  • Resistor Value5k Ohm
  • Heat Range5
  • Torque SpecsCast Iron: 18-25.3 lb. ft. Aluminum: 18-21.6 lb. ft.

  • Part Information
  • BrandNGK/NTK
  • Warranty60 Days
  • Longevity100k Miles
 

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3,773 Posts
None of them look horrible. But, quite a difference from dirtiest to cleanest. I always back them out 2 turns and use shop air to blow out the holes before removing them. Assures no grit on the counterbore. Almost all 'good' sparkplugs come from factory with a type of anti-sieze on the threads. Best not to add anything else. Take a look in the holes with a strong lite. Wipe any grease, oil, or dirt off the seat. For deep bores (not just the two on the X) I use an old pistol/revolver rod. Drape a clean bit of rag over the brush and give it a squeeze, it will stay on. Like H&F I have never trimmed the wires but I don't think it could hurt.
 

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2008 VTX 1800N, Vance & Hines Big shots exhaust and stock air intake
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I just realized I put this thing on 8k miles ago. You think it's passing dirt and oil? I did not over oil it when installed and it was fully dried. Just a thought. View attachment 208843
Check out Project Farm's video testing air filters on YouTube. A lot of particulate gets by these oiled filters. They do flow more air but it comes at a cost. May or may not be your issue but it's a great video
 

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Discussion Starter · #16 ·
Check out Project Farm's video testing air filters on YouTube. A lot of particulate gets by these oiled filters. They do flow more air but it comes at a cost. May or may not be your issue but it's a great video
Wow. Yeah, that video was very well done. I may be switching out that kn filter. Thank you for that.
 

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I have noticed that on mine the plugs on the timing chain side of the cylinder tends to build up more carbon than the other side. I also seem to have a problem with oil in the cylinders. It does not smoke, and I never have to add any between changes, but there is always a little oil on the plugs.
 

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They are large cylinders. When riding my X on long hauls (several tanks of fuel) it would use some oil. Never a lot. And, never smoked nor had wet pipes. The thing has always ran so damn well that I never 'checked' the plugs except for at maint..
 

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They are large cylinders. When riding my X on long hauls (several tanks of fuel) it would use some oil. Never a lot. And, never smoked nor had wet pipes. The thing has always ran so damn well that I never 'checked' the plugs except for at maint..
Yes, Huge cylinders, with a very long stroke, which means lots of variations in crankcase pressure as the pistons move up and down. Which is why there is always oil in the breather as well.
 
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