When to replace spark plugs?

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Apr 20, 2011 | 07:17 PM

#31

smithbrl

Road Warrior

Joined: Oct 2008

Posts: 1,692

Likes: 22

From: Denham Springs, La

I change mine usually around 20k. I use a dab of never seize on the threads and tighten them snugly. They've been working fine til I replace them. I haven't had any trouble removing them and they've never come loose or fallen out.

Cecil

Apr 20, 2011 | 07:21 PM

#32

qtrracer

Ultimate HDF Member

Joined: Jan 2008

Posts: 6,532

Likes: 132

From: SoCal

I just bought some Autolite 4164's and lo and behold they are 18mm, not 5/8". I couldn't figure out why the damn plug socket didn't fit, luckily I already had an 18mm plug socket to do my clutch adjustment because of my VPC.

Apr 20, 2011 | 10:24 PM

#33

Neggy ZRXOA 5248

Stellar HDF Member

Joined: Nov 2005

Posts: 3,183

Likes: 836

From: KMHT KFMY

Quote:

Originally Posted by 69cj

I guess the auto repair manuals that I have including the work shop manuals are wrong then? I use it and have never had a problem, however, I do use a torque wrench, not the monkey arm method.

As long as you are aware that the torque spec is for dry or lubricated threads I guess you are fine. Kind of like the torque specs in a Machinery's Handbook are for lightly lubricated threads. Try to torque a lubricated fastener to a dry fastener specified torque in a soft material and you may damage the threads

Using a torque spec for a non lubricated thread on a lubricated thread, the lubricant being oil, anti seize, or even a anaerobic thread locking compound especially into aluminum can distort the pitch, pull the threads right out, or cause a failure of the fastening system when it is stretched past it's yield strength.

Apr 20, 2011 | 10:28 PM

#34

douglassrider

Stage I

Joined: Apr 2011

Posts: 1

Likes: 0

From: Wichita

I have an '08 Ultra Classic with 47000 miles on it and I still have the original spark plugs in it. Still runs fine.

Apr 20, 2011 | 11:22 PM

#35

qwest

Cruiser

Joined: Oct 2007

Posts: 130

Likes: 0

Once a year. I pull the plugs every year when I spray some fogging oil in the cylinders for winter storage.

I put a little dielectric grease in the plug wires and replace the plugs at the same time.

May 1, 2017 | 06:14 AM

#36

deluxesteve

Intermediate

Joined: Aug 2016

Posts: 26

Likes: 4

From: North Carolina

Cross referenced oem spark plugs.

Quote:

Originally Posted by 69cj

If they look good there's no reason not to get 30,000 miles out of them. I also have not seen any cross matched plugs to the Harley plugs. Some one else may have but not me.

I just replaced my plugs at 10 I used NGK Iridium IX Spark Plug (DCPR7EIX)
made a nice difference in starting up... seems to fire up immediately and is a fine oem replacement according to harley dealership. ..

May 1, 2017 | 06:22 AM

#37

deluxesteve

Intermediate

Joined: Aug 2016

Posts: 26

Likes: 4

From: North Carolina

Quote:

Originally Posted by 69cj

If they look good there's no reason not to get 30,000 miles out of them. I also have not seen any cross matched plugs to the Harley plugs. Some one else may have but not me.

just replaced plugs at 10 using

NGK Iridium IX Spark Plug (DCPR7EIX)

Harley dealership said they were a s good as a oem replacement..bike fires up better quicker..feels to have better throttle response ... and immediately saw a fuel mileage gain..will buy again..

May 1, 2017 | 06:24 AM

#38

Notgrownup

Seasoned HDF Member

Joined: Mar 2009

Posts: 24,711

Likes: 9,215

From: Snow Hill, NC

To each his own...they last pretty good if your motor runs right. I like double platinum and I leave them in until they are bad, I usually check them periodically. Some change them every 5000 miles, do what makes you feel good. If the bike runs fine and the plugs are clean, they probably are ok.

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May 1, 2017 | 07:28 AM

#39

TheGrandPoohBah

Extreme HDF Member

Joined: Jun 2011

Posts: 14,731

Likes: 2,536

From: Mountain Top, Alabama

Pull 'em, clean 'em, read 'em, gap 'em, anti seize the threads, make sure tips are tight, little dielectric where the cables snap on, torque 'em down, run 'em. Mine are over 30K and rolling. When they start showing wear or not doing right, I will replace 'em with the stock plugs.

May 1, 2017 | 08:04 AM

#40

deluxesteve

Intermediate

Joined: Aug 2016

Posts: 26

Likes: 4

From: North Carolina

spark plugs

Quote:

Originally Posted by TheGrandPoohBah

well i was riding in the mountains of north carolina and noticed that on a incline if i would roll a little harder than normal i detected a faint stumble..if i roll harder it would go away or if i let up a little it would stop..just sorta holding it steady but on the throttle a little faint stumble..i stopped and picked up 2 of above mentioned plugs from auto zone after speaking with dealership about warranty issues ..as i took the rear one out i dropped it and it closed gap all the way so i couldn't check it but the front one was on 42 which it calls for 38 to 42..i hit the middle at 40 with the new ones..upon replacing them when i hit the starter it fired before i could hardly let go of the start button which all its life seemed to turn over once before firing up..that went away immediately..took it for a test ride and i'm not sure if i just got use to it over time or it had just started but i had a amazing amount of throttle response that was not there prior to changing them out..now when i roll on a hill it pulls hard with zero stumble of any kind..they were a little expensive about $8 each..then sunday we went for a ride of about 150 miles and i noticed i had more fuel than normal after 150 miles. so i stopped filled back up to check and was getting about 46mpg when previous to that about 40mpg..maybe could have been cleaned, regapped and installed and took care of it but for $16 and 5 minutes im a happy camper with the outcome i got out of it so far..

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