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[Rimjam]

Do any of you guys who change your spark plugs annually or every 10K miles do it because of plug failure or misfire?  I ask this because I periodically check mine just to see internal cylinder condition (fuel ratio, oil useage, etc.) but I don't change plugs just as a normal maintenance item.  My '80 Sturgis is on its second set of plugs, my '94 Road King and '00 SERG are still on their ORIGINAL plugs without any noticeable problems.  Am I missing something here?

[SBB]

Do any of you guys who change your spark plugs annually or every 10K miles do it because of plug failure or misfire?  I ask this because I periodically check mine just to see internal cylinder condition (fuel ratio, oil useage, etc.) but I don't change plugs just as a normal maintenance item.  My '80 Sturgis is on its second set of plugs, my '94 Road King and '00 SERG are still on their ORIGINAL plugs without any noticeable problems.  Am I missing something here?

That thought process goes along with,
"I haven't changed oil in 20K miles but I just checked and there's still some in there so I guess I'm ok"
But then again if the Sturgis, 94 RK and 00 SERG have less than 5K miles then who cares.

 

SBB

[HOGMIKE]

Years ago, I was at a show and bought some Beru plugs for my EVO. I was on a "test" to see how they worked.
I put about 80K miles on that engine with those plugs, took them out a couple of times just to see what they looked like. Looked fine, and only changed them when I replaced the motor. I usually don't even worry about plugs unless I get about 50K, then pull them out for a look.
If they are degrading, I sure can't tell.

[2018_FLTRXSE]

Years ago, I was at a show and bought some Beru plugs for my EVO. I was on a "test" to see how they worked.
I put about 80K miles on that engine with those plugs, took them out a couple of times just to see what they looked like. Looked fine, and only changed them when I replaced the motor. I usually don't even worry about plugs unless I get about 50K, then pull them out for a look.
If they are degrading, I sure can't tell.

Preventive maintenance for spark plugs is a carryover from the carbureted days... However, more sensitivity to resistance changes are noted for modern computer controlled vehicles (EFI)

2 plugs are cheap, and easy insurance... so why not?.

I do the same for my older cars.. once a year....

[Talon]

You get a better spark with a Sharp edge on the electrode, after time the edge starts to round off, causing a weaker spark. This is the reason to change more often, all the iridium and other special additives do is to help reduce this wear.

Craig

[2018_FLTRXSE]

You get a better spark with a Sharp edge on the electrode, after time the edge starts to round off, causing a weaker spark. This is the reason to change more often, all the iridium and other special additives do is to help reduce this wear.

Craig

Correct... spark leaves off the corners or sharp edges.. the theory behind that fuels things like "V-power or U-groove plugs.

The smaller the electrode (or less firing area) the theoretically shorter life.

[Rio]

Wow, time for this thread to end.  I decided to keep it simple and change ALL the fluids, change the plugs, air cleaner every season period.  For $100 it's the cheapest and most important way to make sure your bike is maintained for long term reliabity. 
Heres a picture, she's all ready for some warm weather.  I went with the full black Rinehart system with performance baffles, they sound awesome!  Also, I have the George Anderson tour pack relocator on and set back about 2".  I added Hot Toppers around the engine, tough to see, just to give it some shine with all the black on the bike.  Just need some SPRING weather!!!

[dlaws01]

Crimson, love the totally black theme. Great looking bike!

[Hekterr]

Hi There,

  i read through this thread and was wondering if anybody actually "read"  they're plugs?? As in Rich or Lean mixture ,burnback (how clean or carboned.)
Was specifically looking to see what guys with well tuned Hi-perf 103 's were using.NGK website plug finder recommends a DCPR7E.. I was also wondering if anyone with a 10.5-11 to 1C.R. 103 had tried a DCPR8E or DCPR9E with timing advanced a little..
  Just looking for a little more...
My Nascar background just won't let me leave well enough (stock) alone...

             Thanks,Dave

[hbens]

A couple of the replies indicate they are reading their plugs. One rider has had the same plug for many 1000's of miles and has removed and looked at them a couple of times. He put them back in and is running strong (near as he can tell).

[SteveO]

HD Plugs once a year.

[grc]

BTW, Harley changed the recommended plug maintenance to 20k miles a couple years back, and it looks like they've changed it to 30k miles for 2012.  I love it when they slowly creep into the same century as the rest of the industry.  What's next?

2012 Service Changes:
Service interval change for spark plugs for all models (30K or every 2 yr.)
Fuel filter change interval changed to 100,000 miles for all models.


Jerry