Plug Question

[HaulinAshe]

Where I don't mind running a set of plugs in my Merc engine 30 thousand miles, I just can't imagine doing the same in my FJR.

+1 Rad. That was my point too. Change the damn plugs as scheduled. Buy the best you feel appropriate. But change the damn plugs!!!

 

[user 213]

Awwwwww Radman, don't feel so bad. And hey, you can forget the first 30 years of that knowledge now.

If it makes you feel like you're treating Frank better to do it your way, where's the problem? Not being 'in the business', the Iridiums cost me $39.80 a couple years back.

The simple truth is everyone rides differently. Everyone has a differnt feel. Some can notice incremental changes in performance, others can't. Some ride the heck out of their bikes, others are less stressful on their machines.

Me? I see 10k plus from my rear tires, get 46-48 mpg nearly all the time, (rallies excluded), and only ride for fun, no daily commuting. Others get better MPG and more tire life than I do. Others get sub 4k from their tires and call that excellent wear and never see mpg in the 40's, but they're having fun and enjoying their FJR just as much as I am. Neither is wrong.

Spark plugs? Contrary to what some have said in this thread, there is no absolute time to change them. It depends on how the bike is ridden, and what the rider is capable of feeling. They're damn sure not "worn out" at 16k. Is performance reduced? Probably. Enough that I can notice? Hell no. Enough that someone else can? Perhaps.

You treat Frank like the prince he is and spare nothing. I'm a cheap ******* and hardly ever even wash my FJR. You may disagree with my methods, as I disagree with yours, but neither of us is wrong.

So lighten the hell up.

And Dale, don't make me call you out brother. You know how much you've been riding lately.

 

[Warchild]

Yep, I know exactly how much I've been riding lately. It's like.... every day. Every single day, regardless of weather.

Pretty much have too, since I don't own a car.

 

[Windjammer]

This is why I need to shy away from these discussions. Someone asks advise, I offer what I've learned over 40+ years of wrenching on both street and race machines, reading thousands of tech papers, articles, books, and hands on experience on almost every type of engine known to me.

Keep in mind that for every time someone disagrees with you, there are prolly 500 people who read your advice and gain something from it, but remain silent. Don't shy away - keep posting your opinions.

There are a lot of variables that determine spark plug life. If your EFI is out of synch, you may end up with a plug that fouls just a bit. Ditto if your bike begins to develop "the tick" (God forbid) - one or more plugs could oil foul. And the FJR is a high perf motor - it will generate greater amounts of localized heat compared to most car engines that are in a mild state of tune. The plugs are literally at the center of that greater localized heat. different fuels, the additives you put in (or don't put in), whether your air cleaner is kept clean, and on, and on, and on!

For those going through their first plug changes, it's safest to change too often at first, then decide whether or not to extend the interval based on what you see when you remove the old plugs (whatever brand or type you choose). And whatever you increase the interval to, leave yourself a safety margin to account for any changes in operating condition. Pushing it to the limit on such a relatively cheap item would be asking for trouble.

 

[user 213]

Yep, I know exactly how much I've been riding lately. It's like.... every day. Every single day, regardless of weather.
Pretty much have too, since I don't own a car.

:clapping: :clapping: :clapping:

From the Denso site, (link on FJRTech, btw):

Q. How long will Iridium Last?

A. Iridium use represents the most significant technological advance in automotive spark plug manufacturing, since platinum was introduced in the early eighties. As vehicle manufacturers produce increasingly complex and efficient automobiles, there is a greater need for long-life plugs that can tolerate leaner fuel mixtures and improved combustion processes. DENSO has responded to this need by developing its Iridium alloy, originally for OE applications. For example, many newer Lexus’ and Toyota models carry an ultra long-life Iridium plug variation (.7mm with platinum tipped ground) that is capable of up to 120,000 miles of service. DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.

 

[Windjammer]

Q. How long will Iridium Last?A. Iridium use represents the most significant technological advance in automotive spark plug manufacturing, since platinum was introduced in the early eighties. As vehicle manufacturers produce increasingly complex and efficient automobiles, there is a greater need for long-life plugs that can tolerate leaner fuel mixtures and improved combustion processes. DENSO has responded to this need by developing its Iridium alloy, originally for OE applications. For example, many newer Lexus’ and Toyota models carry an ultra long-life Iridium plug variation (.7mm with platinum tipped ground) that is capable of up to 120,000 miles of service. DENSO Iridium Power plugs, with their .4mm center electrode, have been developed for performance applications. Because gradual wear will “round-off” firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. For this reason, DENSO advises replacement after 30,000 miles.

Most of this is just "Marketing Blather" - it sure sounds nice though!

Also, their entire reference is to automotive applications. Plugs don't run on the road like a tire. The number of times the plugs fire over 30,000 automotive miles will be far lower than the number of times they will fire over 30,000 miles in an FJR. Most cars cruise down the highway at 2000-3000 RPM, rarely exceeding 5000 RPM. Most FJR's cruise down the highway at 4000-5000 RPM, rarely exceeding 9000 RPM. So one could say that 30,000 car miles on a plug is roughly equivalent to 15,000 FJR miles on a plug, if RPM is the only factor you consider. Figure in the greater heat an FJR plug is exposed to, and the numbers change again.

If you believe the Marketing Blather, that is!

 

[user 213]

@Windjammer - that must be the new math?

I would suggest the marketing blather is conservative. I have almost 45k on the same set of Iridium plugs. My FJR isn't hard to start, still gets 46-48 mpg and if it's down on power, I can't tell.

I've seen dyno runs with "old" plugs that were clean and gapped correctly and new ones with zero change in performance numbers.

Maybe I'll change the plugs this winter, maybe not. FWIW, my throttle bodies have remained in sync since 4k too. I keep checking them, but they stay dead nuts on.

I'm sorry, I'm just not going to worry much about things like spark plugs with the direct experience that I have gathered from my own bike and my own riding habits.

 

[Windjammer]

I'm sorry, I'm just not going to worry much about things like spark plugs with the direct experience that I have gathered from my own bike and my own riding habits.

I agree with you 100% bro - for your bike with your riding habits, you're doing right. I'm not trying to tell you that you don't change your plugs often enough. But as shown here:

For those going through their first plug changes, it's safest to change too often at first, then decide whether or not to extend the interval based on what you see when you remove the old plugs (whatever brand or type you choose). And whatever you increase the interval to, leave yourself a safety margin to account for any changes in operating condition. Pushing it to the limit on such a relatively cheap item would be asking for trouble.

I AM saying that others may have a different experience, and until they gain the personal experience with their machine that you have with yours, it is safer for them to err on the side of caution and at least check the plugs more often in the early life of the motor. This forum alone is ample evidence that all FJR's are NOT created or operated equally! B)

 

[jestal]

Keep in mind that the most common reason I have seen in the field for misfiring and spark plug replacement ends up being damaged spark plug boots and terminals pulled off due to removing the boots to "check the plugs." Most spark plug boots and terminals are succeptable to damage from repeatedly pulling the boot off. I've seen "misfiing" plugs returned from warranty cases and the metal terminal from inside the boot was stuck to the spark plug electrode still !!!!

The OEM automotive iridium plugs have the platinum pad on the ground electrode also which eliminates the ground electrode wear and makes the plugs easily last for 100K even firing with a direct fire system as I mentioned in my earilier post. The aftermarket iridium plugs do not have the platinum on the ground electrode but I would still expect them to last for 10's of thousands of miles with unleaded fuel even on a bike at higher RPM's based on what I have seem them do.

Keep in mind that many of the plugs I look at run on dynos for hundreds of hours AT FULL THROTTLE, run thru deliberate detonation testing, A/F sweeps, etc... and they still look fine. The dual platinum and iridium plugs seem just about indestructable under normal conditions.

The only real problem with any sort of OEM spark plug in the field that crops up is when a vehicle is repeatedly cold started many many times (loading/unloading from haulaway truck, marshalling in factory and dealer lots, etc....) and the plug never has chance to heat up and clean off the carbon that normall deposits when cold. This is the "fluffy black carbon" someone mentioned. Likely from the previous start that did not warm the engine up completely and get the plugs to temp to burn off the carbon. If this is repeated many times the carbon becomes thick enough to conduct the spark to ground down the porcelean of the center electrode. This induces a misfire that is noticed immediately but, more importantly, the spark arching down the center porcelean etches a groove in the porcelean that stays there when the carbon burns away. That microscopic groove becomes a haven for deposits and liquid fuel in the future that will cause all sorts of driveability issues including hard starts, stall after start, hesitations, etc. The problems dissappear with the plugs when they are changed. Definitely the plug was "the problem" but the cause was the plug was damaged by excessive marshalling, not the plug design or type or a defective plug. This can be very misleading when someone blames problems on the plugs just because the problem disappears when the plugs were changed. I have seen this phenomenono a LOT. We even have a name for it. It is called "lot rot" for the repeated short starts and stops in shippping and dealer lots. Carbons up the plugs and kills them then due to carbon fouling. Many OEM plugs actually have a proprietary coating on the center electrode porclean to resist this that you probably have never heard about...... To understand this phenomenon better, understand that your new CAR will probably have 50 or 60 starts on it when you take delivery with 2 miles or less on the odometer. Severe cases will have 200 hundred starts on it in 2 miles..... Seriously. That will definitely induce a case of "lot rot" on the plugs. The OEM ECM calibrations even have a special cold start algorithm to help offset lot rot that acts on the fuel injection for the first 2 or 3 miles only.

Any vehicle that receives special upfits (like limosines, cabs, cop cars) can easily have 200 or 300 short starts on it before the car is put into daily service so the chances of one of those cars have lot rot and needing plugs is multiplied compared to normal cars so the plug situation on those vehicles might not be representative. Unless the old plugs are reviewed under an SEM you would never see the microscopic grooves etched into the porcelean by the lot rot.

On another thought, even though we haven't seen leaded fuel in the US for 20 plus years it is still available in many parts of the world and until just the last couple of years was the standard fuel in strange places like Saudia Arabia and other places that reek of petroleum!! Vehicles there need plug changes every 10K at the most because of the lead in the fuel. There are special vehicle/engine calibrations for those export cars that take the leaded fuel into account and there are NON-dual platinum/iridium plugs in the correct heat range released for service for those countries so the owners do not have to spend $100 for a set of plugs every 10K !!! It was quite a complaint item until the standard plugs were made available.

Maybe this helps to understand why I am a bit more confident of the plugs lasting longer than some might imagine.

 

[charismaticmegafauna]

Thank you, jestal -- great write-up on platinum/iridium spark plugs and some causes for failure. All of which I agree with from my experience. The term "lot rot" was new -- but, not the experience. Think of a trailer load of 12 MSF training bikes on cool Spring weekends and novice riders attempting to start unfamiliar engines with, even more unfamiliar, "chokes" -- and you'll get the idea.

Another little thing I'd like to address that's been inferred, at times, during this thread is: the relative level of performance of the FJR's engine. I maintain, by 21st century standards (for sure), it has relatively normal output -- a little over 100 hp / liter. Many rather ordinary auto engines now approach (and some exceed) 100 hp / liter -- for moms to take kids to school and pick-up groceries. For added emphasis, I'll add that H**** sold the CX500TC, a fully-faired, shaft drive, sport-touring bike that had 160 hp / liter -- 25 years ago! And, many modern sport bikes approach 200 hp / liter. The FJR's certainly okay in the power department -- but, no "barn-burner".