Spark plug life

[Bugnatr]

I used to change the plugs more often but reading here how people run them longer I left the current set of Iridum's in the bike now for over 28k. Bike runs fine but I have a 3,500 mile ride coming up next week.

Question- should I change them (I have a set with only 14 k on them I would put in) OR wait until performance or mileage drops before changing them?

Yes I know "if you have to ask-just do it" but I was just wondering if others have logged tons o miles before changing plugs

 

[Warchild]

I'd change them. 28K is a looong service life for a spark plug, even for Iridiums. You can't go wrong with fresh plugs.

 

[roger dodger]

Spend a few $$$ and put in a fresh set. I did the deed @ 20k and it ran slightly smoother from then on....it's gotta help.

 

[SkooterG]

I'd leave them in. Another 3500 miles ain't nothing. I know some peeps who leave normal plugs in for more miles than you have.

 

[Bounce]

Awfully cheap insurance. A few minutes time could save a frustrating event while on the road.

 

[SkooterG]

Awfully cheap insurance. A few minutes time could save a frustrating event while on the road.

When was the last time you personally heard of a spark plug causing a problem - specifically a shut-down of the motor? For me, it is ZERO.

 

[TomInPA]

I agree with the other responses. I ran a set of Iridium plugs to over 24K miles and they were completely spent. The Iridium plug when new has a cylindrical electrode with a sharp well-defined flat end. By the time I removed these, the electrode had eroded to a point. This noticeably affected performance and fuel economy. Inspect your plugs carefully and remember that spark efficiency relies on that edge on teh electrode. When that becomes rounded, or turns into a point, the plug is shot, even though the plug color and condition otherwise looks fine.

 

[Fred W]

I agree with the other responses. I ran a set of Iridium plugs to over 24K miles and they were completely spent. The Iridium plug when new has a cylindrical electrode with a sharp well-defined flat end. By the time I removed these, the electrode had eroded to a point.

Betcha only two of them had. Remember, each coil fires two plugs, one with a positive voltage in respect to ground and the other is negative. The negative side will erode the center electrode, the positive side will erode the side electrode.

That is, unless you rotated your plugs every 15k miles.

On my daughter's high mileage SAAB 9-3, where every plug has a coil-over and they all fire with a negative voltage, after 70k correction 120k miles the center electrodes were like needles and there was a little bump of deposited center electrode platinum on each of the side electrodes. That car used single platinum plugs. No need for platinum on the side electrodes. A picture of one of those plugs and further discussion about iridium vs regular plugs can be found here

On the FJR we could really use double platinum plugs since we are firing them in both directions. Unfortunately, there is no such thing as a double iridium plug. Only the center electrode is iridium. That's why I just buy the cheap regular plugs and replace them at 15 k mile interval. 15k because I do my oil changes on the 5's and it makes it easier to remember. Could probably go to 20k even with the regular plugs.

 

[TomInPA]

I agree with the other responses. I ran a set of Iridium plugs to over 24K miles and they were completely spent. The Iridium plug when new has a cylindrical electrode with a sharp well-defined flat end. By the time I removed these, the electrode had eroded to a point.

Betcha only two of them had. Remember, each coil fires two plugs, one with a positive voltage in respect to ground and the other is negative. The negative side will erode the center electrode, the positive side will erode the side electrode.

That is, unless you rotated your plugs every 15k miles.

On my daughter's high mileage SAAB 9-3, where every plug has a coil-over and they all fire with a negative voltage, after 70k miles the center electrodes were like needles and there was a little bump of deposited center electrode platinum on each of the side electrodes. That car used single platinum plugs. No need for platinum on the side electrodes.

On the FJR we could really use double platinum plugs since we are firing them in both directions. Unfortunately, there is no such thing as a double iridium plug. Only the center electrode is iridium. That's why I just buy the cheap regular plugs and replace them at 15 k mile intervals

Actually, no. This was in a single-fire V-twin. I have been changing plugs at about 14K miles in the FJR. Interesting, I hadn't thought about the reverse arc in the dual fire ignition.

 

[SkooterG]

I agree with the other responses. I ran a set of Iridium plugs to over 24K miles and they were completely spent. The Iridium plug when new has a cylindrical electrode with a sharp well-defined flat end. By the time I removed these, the electrode had eroded to a point.

That might have been the case on your V-twin, but on this forum I have seen photos of plugs pulled out after 20-30k miles that look fine. I used to be a 'change the plugs regularly' kind of guy until I have seen all the anecdotal evidence on this forum suggesting that it is not needed. Nowadays. I run the regular plugs from valve adjustment to valve adjustment or about 30k miles with no degradation of performance, fuel economy, ect.. So I am extremely skeptical of all these folks that come on here and claim that changing spark plugs made such a big difference in how their FJR performs. It's just a friggin spark plug for crying out loud!

Now on the other hand - a Throttle Body Sync will cure all kinds of ills including World Peace!

 

[Bugnatr]

Spark plugs are amazing. I replaced my 01 tacoma's plugs for the first time at 110,000 miles. Man were they worn big time but yet the truck ran the same before and after-go figure <_<

I am going to inspect the plugs (I am with Scooter) but most likely will throw in the ones with only 14k, because I'm headed to cowboy country

 

[odot]

Spark plugs and oil changes and TB syncs....oh my.........

 

[Bugnatr]

Spark plugs and oil changes and TB syncs....oh my.........

I'll drink to that!

 

[Fred W]

Spark plugs and oil changes and TB syncs....oh my.........

I'll drink to that!

You do realize that he's drinking seal blood, right?

But I'm sure that he'll share his Muktuk too. :bad:

 

[HaulinAshe]

... Nowadays. I run the regular plugs from valve adjustment to valve adjustment or about 30k miles with no degradation of performance, fuel economy, ect.. So I am extremely skeptical of all these folks that come on here and claim that changing spark plugs made such a big difference in how their FJR performs. It's just a friggin spark plug for crying out loud!

+1 Skooter

We get a lot of corrosion here along the coast, and I prefer to change plugs every year as part of annual maintenance. I recommend Iridium for people who expect to ride more than 16,000 miles in one year. Everyone else gets the standard CR8-E.