Concours Owners Group (COG) Forum

Concours 14 Discussion (C14 / ZG1400 / 1400GTR) => Concours 14 / ZG1400 General Chat and Tech => Topic started by: Just Cliff on February 13, 2018, 12:56:45 am

Title: Maximum spark plug life?
Post by: Just Cliff on February 13, 2018, 12:56:45 am
Just for general discussion & conversation, not to mention something different to discuss besides tires & oil!

What would one think the maximum mileage of C14 plugs would be. While still running very well & producing good fuel mileage? I know what the book says & that's far to often.

I'll post pictures of my plugs & reveal my mileage once some opinions are posted.

Cliff   :beerchug:
Title: Re: Maximum spark plug life?
Post by: gpd323 on February 13, 2018, 01:25:54 am
Pretty sure they are Iridium plugs, so 60K or more easily. Some say 100K before replacing.

Me? I change them at the valve clearance checks just because the tech is already in there.
Title: Re: Maximum spark plug life?
Post by: Steve in Sunny Fla on February 13, 2018, 02:56:43 am
Pretty sure they are Iridium plugs, so 60K or more easily. Some say 100K before replacing.

Me? I change them at the valve clearance checks just because the tech is already in there.

+1. Steve
Title: Re: Maximum spark plug life?
Post by: concfronc on February 13, 2018, 03:11:35 am
Got 48,000+ on mine and no valve inspect yet.
Title: Re: Maximum spark plug life?
Post by: gsun on February 13, 2018, 04:22:02 am
I changed mine at the first valve check but didn't bother at the second because they were in perfect shape on the first. May change on the next one but they are pricey!
Title: Re: Maximum spark plug life?
Post by: ghostrider990 on February 13, 2018, 11:52:21 am
Good post Cliff -- I was JUST thinking about this the other day.  :beerchug:

Not a great comparison, but most modern cars don't recommend spark plug replacement before 100K.  Same component, same function, albeit higher service load (RPM's).

I'd tend to favor the "if it ain't broke" theory, and judge the condition of the plugs during the valve inspection.

However - Steve's got a point.....while you're IN there.

4 new iridiums will set you back around $40-50

....decisions, decisions....

I'll split the difference and say 50k miles, is a reasonable service life for our bikes.

Title: Re: Maximum spark plug life?
Post by: 4Bikes on February 13, 2018, 12:25:50 pm
I changed my plugs during the second valve check at 40,000 miles. They looked good, but its a great time to do it since you already have the stick coils removed.  15,000 miles is way too early even though it's nearly double the "recommended" interval. 
Title: Re: Maximum spark plug life?
Post by: cuda on February 13, 2018, 06:17:43 pm
Got 48,000+ on mine and no valve inspect yet.





Be careful your going to get banned ;)
Title: Re: Maximum spark plug life?
Post by: Deepsea on February 13, 2018, 07:00:05 pm
60k on the original plugs and still going. I'll probably change them at 80/85k.
Title: Re: Maximum spark plug life?
Post by: PeteTN_zgtr on February 13, 2018, 11:55:57 pm
200K+ on original plugs on two of our cars. Still run smooth although probably losing a few hp.

I'd suspect a C14 would go 100k easy on a set at least. Maybe change at 50 or 60k for best performance.
Title: Re: Maximum spark plug life?
Post by: Just Cliff on February 14, 2018, 01:43:55 am
This is the second new set of plugs installed in my bike. They have 126,665 miles on them & still look good. Bike still ran great & delivers 47 - 50 mpg. No real noticeable in the way it runs with new ones.

Have had Steve's EVO flash (beta test version) for about 28,000 miles. Appears to be burning good.

I didn't think to take side by side pictures for comparison. All 4 plugs are shown.

Appears they can easily go 100,00!  :motonoises:

Cliff   :beerchug:

Title: Re: Maximum spark plug life?
Post by: TimR on February 14, 2018, 04:44:40 pm
No desire to stir the pot but I remember reading Fred Harmon's comments on the C14 spark plug. He claimed there was a reason Mama K wanted the plugs changed at the intervals in the book. As I remember it was not due to the plug not sparking but to lower the chance of the plug failing structurally. Ma K was worried that because of the performance capabilities of the motor they didn't want the chance for pieces of spark plug  floating around in the cylinder. That was my take on what Fred wrote anyways.
Title: Re: Maximum spark plug life?
Post by: Deepsea on February 15, 2018, 02:19:08 pm
These plug routinely go 100k in cars and bikes with higher performance than our C14's. Think 12.5:1 compression drag bikes or even in my twin engine LSR bike at 14-16 psi boost without a structural failure, ever.
Title: Re: Maximum spark plug life?
Post by: Roger B on February 15, 2018, 05:16:20 pm
This is the second new set of plugs installed in my bike. They have 126,665 miles on them & still look good. Bike still ran great & delivers 47 - 50 mpg. No real noticeable in the way it runs with new ones.

Have had Steve's EVO flash (beta test version) for about 28,000 miles. Appears to be burning good.

I didn't think to take side by side pictures for comparison. All 4 plugs are shown.

Appears they can easily go 100,00!  :motonoises:


Hi Cliff, I changed my plugs at 18k when I did my valve adjustment.   I might not change them at the next valve adjustment per your usage.   How has your motor held up as far as oil usage and leakage?  Ever do a compression check?   How about the drivetrain?   I just think you are a great C14 mule on what can be expected out of the C14 and was curious.
Thanks.
Roger in Ohio

Cliff   :beerchug:
Title: Re: Maximum spark plug life?
Post by: Just Cliff on February 16, 2018, 12:17:54 am
This is the second new set of plugs installed in my bike. They have 126,665 miles on them & still look good. Bike still ran great & delivers 47 - 50 mpg. No real noticeable in the way it runs with new ones.

Have had Steve's EVO flash (beta test version) for about 28,000 miles. Appears to be burning good.

I didn't think to take side by side pictures for comparison. All 4 plugs are shown.

Appears they can easily go 100,00!  :motonoises:


Hi Cliff, I changed my plugs at 18k when I did my valve adjustment.   I might not change them at the next valve adjustment per your usage.   How has your motor held up as far as oil usage and leakage?  Ever do a compression check?   How about the drivetrain?   I just think you are a great C14 mule on what can be expected out of the C14 and was curious.
Thanks.
Roger in Ohio

Cliff   :beerchug:

Hmmm, I've been called a lot things Roger but never a mule.  :)

Does not use any oil or smoke. The valve cover gasket has been seeping for sometime on the left front corner. Gasket was original to the bike until this valve check. Cam sensor O ring has never leaked, was also factory. Replaced it at this service with over sized O ring. Other than valve cover, no leaks. Also replaced the chain tensioner at this service. This was all done at 194,925 miles.

No compression checks, but wish I would have.

No problems with the drive-train. Change differential fluid at every oil change, 5,000. Clean & grease hub splines at every tire change, which is often.

1 complete set of wheel bearings  & seals, 2 sets of plugs & 3 valve adjustments to date. Replaced lower fork tubes because chrome finish had worn off. Never leaked, but they would eventually.

If I commuted or ran errands on this bike it would have miles on it!  :motonoises:

Cliff   :beerchug:
Title: Re: Maximum spark plug life?
Post by: rcannon409 on February 16, 2018, 02:23:12 pm
A long time ago, I had a 2004 Suzuki rm 125.  Its spark plug was an NGK R6918 b8.  NO big deal, except the dealer wanted $55.00 for them....each.  Not for  a case....

Visually, the plug looked similar to a br8eg. Many people used the cheaper br8eg plug. I remember a few failures, but not often.

I called NGK and someone explained the r6918 had its center electrode hand welded and was a "motorcycle specific" plug.

They claimed this specific bike had some sort of vibration pattern that could cause the electrode to fall off of the br8eg and destroy the motor. Rather than address the issue, Suzuki just used an expensive, hand made plug.

I suspect the idea here is similar. Since the plug is not "motorcycle specific", its better to ask for extremely early replacement rather than use a 45.00 dollar plug.

Title: Re: Maximum spark plug life?
Post by: worncog on February 16, 2018, 02:47:47 pm
Last time I checked the Iridium plugs in my antiquated C10, they had ~75k on them and all I did was readjust the gap slightly to compensate for wear. Mileage would be higher, but I got a new girlfriend and she goes everywhere.

Title: Re: Maximum spark plug life?
Post by: Roger B on February 16, 2018, 06:16:01 pm
This is the second new set of plugs installed in my bike. They have 126,665 miles on them & still look good. Bike still ran great & delivers 47 - 50 mpg. No real noticeable in the way it runs with new ones.

Have had Steve's EVO flash (beta test version) for about 28,000 miles. Appears to be burning good.

I didn't think to take side by side pictures for comparison. All 4 plugs are shown.

Appears they can easily go 100,00!  :motonoises:


Hi Cliff, I changed my plugs at 18k when I did my valve adjustment.   I might not change them at the next valve adjustment per your usage.   How has your motor held up as far as oil usage and leakage?  Ever do a compression check?   How about the drivetrain?   I just think you are a great C14 mule on what can be expected out of the C14 and was curious.
Thanks.
Roger in Ohio

Cliff   :beerchug:

Hmmm, I've been called a lot things Roger but never a mule.  :)

Does not use any oil or smoke. The valve cover gasket has been seeping for sometime on the left front corner. Gasket was original to the bike until this valve check. Cam sensor O ring has never leaked, was also factory. Replaced it at this service with over sized O ring. Other than valve cover, no leaks. Also replaced the chain tensioner at this service. This was all done at 194,925 miles.

No compression checks, but wish I would have.

No problems with the drive-train. Change differential fluid at every oil change, 5,000. Clean & grease hub splines at every tire change, which is often.

1 complete set of wheel bearings  & seals, 2 sets of plugs & 3 valve adjustments to date. Replaced lower fork tubes because chrome finish had worn off. Never leaked, but they would eventually.

If I commuted or ran errands on this bike it would have miles on it!  :motonoises:

Cliff   :beerchug:


I meant test mule.  Pretty darn good reliability record...never thought about the chrome finish to wear off the fork tubes.  Excellent life out of the wheel bearings.  Would of expected steering head bearings also.  Keep going Cliff.
Title: Re: Maximum spark plug life?
Post by: Just Cliff on February 16, 2018, 10:54:11 pm
This is the second new set of plugs installed in my bike. They have 126,665 miles on them & still look good. Bike still ran great & delivers 47 - 50 mpg. No real noticeable in the way it runs with new ones.

Have had Steve's EVO flash (beta test version) for about 28,000 miles. Appears to be burning good.

I didn't think to take side by side pictures for comparison. All 4 plugs are shown.

Appears they can easily go 100,00!  :motonoises:


Hi Cliff, I changed my plugs at 18k when I did my valve adjustment.   I might not change them at the next valve adjustment per your usage.   How has your motor held up as far as oil usage and leakage?  Ever do a compression check?   How about the drivetrain?   I just think you are a great C14 mule on what can be expected out of the C14 and was curious.
Thanks.
Roger in Ohio

Cliff   :beerchug:

Hmmm, I've been called a lot things Roger but never a mule.  :)

Does not use any oil or smoke. The valve cover gasket has been seeping for sometime on the left front corner. Gasket was original to the bike until this valve check. Cam sensor O ring has never leaked, was also factory. Replaced it at this service with over sized O ring. Other than valve cover, no leaks. Also replaced the chain tensioner at this service. This was all done at 194,925 miles.

No compression checks, but wish I would have.

No problems with the drive-train. Change differential fluid at every oil change, 5,000. Clean & grease hub splines at every tire change, which is often.

1 complete set of wheel bearings  & seals, 2 sets of plugs & 3 valve adjustments to date. Replaced lower fork tubes because chrome finish had worn off. Never leaked, but they would eventually.

If I commuted or ran errands on this bike it would have miles on it!  :motonoises:

Cliff   :beerchug:


I meant test mule.  Pretty darn good reliability record...never thought about the chrome finish to wear off the fork tubes.  Excellent life out of the wheel bearings.  Would of expected steering head bearings also.  Keep going Cliff.

Yep, you got me Roger. I was going off memory, checked my log book & left out a few things.

Radiator hoses at 117,000 - Steering stem bearings at 121,000  - front rotors at 130,000.

Cliff   :beerchug:
Title: Re: Maximum spark plug life?
Post by: Jeremy on February 18, 2018, 06:04:59 am
I just replaced mine with 16,500 on the clock. I shouldn't have wasted the money, the old ones look fine and gaped with in spec. I put the new ones in out of principle since I had already bought them and wasn't driving back to the dealer to return them. I put the old ones in the box and in my parts drawer for later down the road.
Title: Re: Maximum spark plug life?
Post by: DDZX14 on April 09, 2018, 04:19:50 pm
Spark plugs with 44,000 miles under a microscope show molten balls and worn ground electrode. The engine is digesting this stuff.
http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995 (http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995)
Title: Re: Maximum spark plug life?
Post by: TimR on April 14, 2018, 01:13:19 pm
According to the link in reply 20, the Iridium sparkplugs shown must of been pretty bad cause the owner said:   

Quote
My new spark plugs make my ninjee feel like it has a fresh new snappy pair of pure white briefs!

An interesting way of describing how new plugs are working on your motorcycle...... :loco:

Title: Re: Maximum spark plug life?
Post by: mnbikeguy on April 14, 2018, 02:11:43 pm
Spark plugs with 44,000 miles under a microscope show molten balls and worn ground electrode. The engine is digesting this stuff.
[url]http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995[/url] ([url]http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995[/url])


I looked at the picture and those are deposites and have almost nothing to do with the plug integrity. It's a Ninja forum and the guy is probably putting something in the gas and flogging the crap out of it.
Title: Re: Maximum spark plug life?
Post by: Steve in Sunny Fla on April 14, 2018, 02:26:01 pm
Spark plugs with 44,000 miles under a microscope show molten balls and worn ground electrode. The engine is digesting this stuff.
[url]http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995[/url] ([url]http://zx14ninjaforum.com/messages.cfm?threadid=759E7173-0E24-22A8-81F439F41CBC0995[/url])


I looked at the picture and those are deposites and have almost nothing to do with the plug integrity. It's a Ninja forum and the guy is probably putting something in the gas and flogging the crap out of it.




Agreed - look at the edges of the electrode, just very slightly rounded as compared to brand new. All the deposits are from the fuel, not the spark plug erosion. Nice pics though. He should stick to photography, not engine diagnosis. Steve
Title: Re: Maximum spark plug life?
Post by: Deepsea on April 14, 2018, 04:33:52 pm
+1 what Steve said.
Title: Re: Maximum spark plug life?
Post by: Harry Martin on April 15, 2018, 02:05:15 am
If you decide not to replace your plugs, then I highly recommend this video on how to properly clean them.

! No longer available (http://www.youtube.com/watch?v=SbTWLdT_tgk#)