Spark Plug Changes

I posted the below question on another thread that was closed to prevent bloodshed. Mr. jestal, can you help me out here?

Ok Mr jestal, I'll ask this question (and I'm not trying to be a smartass - I'm trying to continue my education!) - I have (because I forgot all about spark plug maint until I read this thread!!) 22.5k miles on my iridium plugs. Haven't cleaned/gapped or done anything to them. Bike runs great as far as I can tell. I just ordered 4 more iridium plugs - when they get here should I put 'em on the shelf, or replace the plugs in the bike?
I know, I know, "it depends on the tactical situation." So.......other than a set period of time to change plugs (preventative maint), what might some symptoms be that would indicate it's time to change plugs (condition based maint)?

Thank you sir.

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Seems your asking Jestal only this question,.

Here's a tip, order the new ones, once recieved compare the new and old paying attention to the carbon build up and the amount of wear or spark errosion of both the centre electode and the outers

First, my name is not Jestal.

I had 30k miles on the iridiums in my '05 FJR and when I took them out to replace they looked almost new.

Since I had them out already I replaced but this set will go at least 40k before replacing.

If your gas mileage starts going down a couple mpg its either time for 1) throttle body sync or 2) spark plugs

Some on this forum would have you believe your plugs at not firing/shot at 10k miles but the FJR burns so cleanly it just is not true.

Jim,

I'm in the same boat as you, almost 20K on Iridiums and haven't even thought about replacing them, until reading this. They look similar to the premium (platinum?) eom plugs in my Infiniti that are scheduled for replacement every 100,000 or so miles.

My FJR starts and runs fine, can still get over 50mpg if I try.

I'll be following this thread with interest.

Charlie

Charlie Hoss said:

Jim,
I'm in the same boat as you, almost 20K on Iridiums and haven't even thought about replacing them, until reading this. They look similar to the premium (platinum?) eom plugs in my Infiniti that are scheduled for replacement every 100,000 or so miles.

My FJR starts and runs fine, can still get over 50mpg if I try.

I'll be following this thread with interest.

Charlie

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Yeah, yeah... The real thing is we (true) Yankees (not those baseball putzes from NYC) are just tighter than a ducks ass!! Why buy plugs if'n ya don't need 'em, right Charlie?

Anyway, I'm getting ready to change my (original) plugs and they have over 16k miles on them. It's running just a bit rougher (I think) with a little more vibration in the 4k - 5k rpm range, but it could be just a TBS needed. I'll let you all know how they look when I get 'em out.

I'll toss in a few general points to ponder:

1. Comparing performance of plugs used in a car vs those used in a bike like the FJR is kinda pointless. Cars run at generally lower RPM than the FJR, hence their plugs fire far less often per mile. This may not ALWAYS be true, but it is generally true. Cars that have a greater number of cylinders than the FJR will also fire their individual plugs far less often.

2. Anecdotal evidence on spark plugs is almost meaningless too. "I drove xxx miles without replacing my Brand X plugs" means nothing to me. Your driving habits (average engine speed), engine condition, fuel quality, etc all may differ from mine, and this has the potential to dramatically affect plug life over the long haul.

3. There's more to plug "wear" than the condition of the electrode. Internal resistance of the plug changes over the life of the plug, and there's no way to measure that by looking at the electrode.

I'm not telling you how often to change your plugs, or to change them more often than you do. I am saying that each person's experience with a particular plug can differ significantly based on many variables. The safest thing to do is to err on the safe side for the first couple of plug changes, then let experience be your guide as you gain knowledge of how the machine and it's components wear in your usage environment.

Fred W said:

Charlie Hoss said:

Jim,
I'm in the same boat as you, almost 20K on Iridiums and haven't even thought about replacing them, until reading this. They look similar to the premium (platinum?) eom plugs in my Infiniti that are scheduled for replacement every 100,000 or so miles.

My FJR starts and runs fine, can still get over 50mpg if I try.

I'll be following this thread with interest.

Charlie

Click to expand...

Yeah, yeah... The real thing is we (true) Yankees (not those baseball putzes from NYC) are just tighter than a ducks ass!! Why buy plugs if'n ya don't need 'em, right Charlie?

Anyway, I'm getting ready to change my (original) plugs and they have over 16k miles on them. It's running just a bitrougher (I think) with a little more vibration in the 4k - 5k rpm range, but it could be just a TBS needed. I'll let you all know how they look when I get 'em out.

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Fred,

Correctamundo. Wait 'til the Friday Night Dogpilers see this......we're too cheap to invest $15 to $25 to protect our $13000 investment!! I'll start getting my Social Insecurity checks beginning in December. Maybe I'll order up a set then .................

naaaaah.

Windjammer said:

I'll toss in a few general points to ponder:
1. Comparing performance of plugs used in a car vs those used in a bike like the FJR is kinda pointless. Cars run at generally lower RPM than the FJR, hence their plugs fire far less often per mile. This may not ALWAYS be true, but it is generally true. Cars that have a greater number of cylinders than the FJR will also fire their individual plugs far less often.

2. Anecdotal evidence on spark plugs is almost meaningless too. "I drove xxx miles without replacing my Brand X plugs" means nothing to me. Your driving habits (average engine speed), engine condition, fuel quality, etc all may differ from mine, and this has the potential to dramatically affect plug life over the long haul.

3. There's more to plug "wear" than the condition of the electrode. Internal resistance of the plug changes over the life of the plug, and there's no way to measure that by looking at the electrode.

I'm not telling you how often to change your plugs, or to change them more often than you do. I am saying that each person's experience with a particular plug can differ significantly based on many variables. The safest thing to do is to err on the safe side for the first couple of plug changes, then let experience be your guide as you gain knowledge of how the machine and it's components wear in your usage environment.

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Well then, I guess we could stop all this talking about it since there is no benefit in exchanging experiences... right?

I still think 8k mile plug changes are foolishness.

I thought I read one time that it is the inetrnal resistance that wears down and that causes undue wear/stress on your coil, so simply reading them may not be sufficient. I will do 16k mile intervals on my FJR iridiums and 16k on the Shadow (they are supposed to be replaced every 4k on that bike!). I figure for $35 it's worth it every 16k. Heck, I'll go through 2 sets of tires (maybe 2.5!) in that same time.

dbvolfan said:

I thought I read one time that it is the inetrnal resistance that wears down and that causes undue wear/stress on your coil, so simply reading them may not be sufficient. I will do 16k mile intervals on my FJR iridiums and 16k on the Shadow (they are supposed to be replaced every 4k on that bike!). I figure for $35 it's worth it every 16k. Heck, I'll go through 2 sets of tires (maybe 2.5!) in that same time.

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Well, if you read it on the in-tar-net, it has to be true... :dribble:

Well then, I guess we could stop all this talking about it since there is no benefit in exchanging experiences... right?

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There's nothing wrong with exchanging experiences, but it's helpful if people understand which pieces of information have the most (or the least) value, and why. That's why I posted. In any discussion of product performance, whether it's tires, plugs, oil, or whatever, it helps if one understands the application variables involved, and how they could affect outcomes for different users. That doesn't make discussion of various pieces of information 100% meaningless, it just helps keep them in their proper place.

I still think 8k mile plug changes are foolishness.

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In general, I wouldn't disagree with you. But there are SOME rider/bike combinations who could consume a set of plugs in that time (or less). Other rider/bike combinations might make the same brand of plugs last 30k miles or more. It all depends on how they're used, and the environment they're used in.

JimLor said:

I posted the below question on another thread that was closed to prevent bloodshed. Mr. jestal, can you help me out here?

Ok Mr jestal, I'll ask this question (and I'm not trying to be a smartass - I'm trying to continue my education!) - I have (because I forgot all about spark plug maint until I read this thread!!) 22.5k miles on my iridium plugs. Haven't cleaned/gapped or done anything to them. Bike runs great as far as I can tell. I just ordered 4 more iridium plugs - when they get here should I put 'em on the shelf, or replace the plugs in the bike?
I know, I know, "it depends on the tactical situation." So.......other than a set period of time to change plugs (preventative maint), what might some symptoms be that would indicate it's time to change plugs (condition based maint)?

Thank you sir.

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Here is something to think about with ignition systems. The wider the gap in the plug the more energy it takes to jump the gap and keep the spark flowing. As the energy increases it stresses all the ignition components more. You will not notice this increase in energy required to jump the spark plug gap. What you notice is when the spark finds an easier place to flow to like a carbon track on the spark plug insulator. This you will notice as the spark is in the wrong place and will not ignite the molecules of fuel in the gap. So you may not notice anything wrong until a coil overheats and fails or the spark is shorting at the plug wires. Worse than that is the secondary ignition system is so well insulated the energy flows back to the ignition module and causes the power transistor to fry.

In my opinion plugs are cheap compared to all the other possiblities.

I run Iridium plugs and will change them at 15,000 miles.

I view maintenance of the FJR in the same way as maintenance on any experimental, unlicensed aircraft. The FAA/Yamaha is not going to dictate my maintenance schedule, only suggest one. It's up to me to find the best balance between expense $$$, down time, and potential equipment and personal risk.

So I change plugs less often than recommended for the stock CR8E and more often than required for the CR8EIK Iridiums in the typical 6-cylinder cager. That works out to every 25,000 miles or one year, whichever comes first. Even if the plugs are operating fine, you have to remember that leaving them for a very long time, may greatly complicate the eventual removal.

Also, just how long are you willing to operate your engine without taking a $40 look at its "insides". The plug condition can offer a look at potential/impending problems. At least once per year works for me.

JeffAshe said:

At least once per year works for me.

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Doesn't for me. Why would you go 3x the replacement interval on mileage and then create a one-year time-based replacement schedule when none is required? Plugs don't wear out sitting in there and if corrosion is of concern (probably isn't for 95% of riders), then use some spark plug anti-sieze.

If you're going to deviate from Yamaha's suggested intervals, you need to have some reasonable basis. I'd stick to Yamaha's schedule.

- Mark

markjenn said:

If you're going to deviate from Yamaha's suggested intervals, you need to have some reasonable basis. I'd stick to Yamaha's schedule.

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I do have a reasonable basis.

Every 20-25,000 miles using Iridiums, or one year, whichever comes first.

You didn't read all my previous post. I want to look at the plugs at least once per year, regardless of the mileage. So even if I don't do 25,000 in that year (which is RARE), I go ahead and replace the plugs. After all, why would pull the plugs for inspection and NOT change them??? That would not make any sense to me.

Thank you all for posting.

After reading all these posts I've come to the conclusion that the concensous is.........ain't one! Had the brief possibility of internecine warfare, but that seemed to pass pretty quietly. What I was hoping for was, "Take your voltmeter and put one lead on the top, one on the bottom and it should read between x and y if the plug is good." Like they say, you can hope in one hand and crap in the other and guess which one will fillup first? (hint - the one you crapped in)

I have 22k on my iridiums and Maxine runs just fine. I'm going to take my new plugs and throw them into my parts bin. What will probably happen is that on one lazy day I'll feel the need to putter/tinker - and I'll change the plugs.

Thanks again!

Plugs are like oil filters. How do you know when your oil filter is getting clogged? You don't. You just keep em changed so that nothing bad happens.

Now, everybody go change their frickin' plugs. It only takes 10 minutes. The EPA will thank you.

JimLor said:

After reading all these posts I've come to the conclusion that the concensous is.........ain't one!

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Aaaaaaand once again, we see the reason for the existence of the NEPRT forum!

The 8K plug change interval is needed *IF* you continue to stay with the low-end NGK copper plugs that come stock from the factory.

The primary reason to switch to Irridiums is not increased performance... it's to increase plug lifespan.

Windjammer said:

Cars that have a greater number of cylinders than the FJR will also fire their individual plugs far less often.

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Any car or any engine (4 stroke) for that matter, no matter how many cylinders, 1, 2, 4, 6, 8, 10, 12, will fire their spark plugs once every other revolution.

A V12 Mercedes engine will fire it's plugs the same # of times as our FJR's will at 4,000 RPM's.