Pics, iridium plugs after 24,000

UHOH · May 22, 2010

Some people work religiously to keep up with the Yamaha scheduled maintenance.

I choose which ones to do; one I let go much longer is plug replacement.

Just pulled the ‘long life’ iridium plugs @ 24,000 miles vs. the scheduled 8,000 mile plug change interval.

Wanted to show you how they looked, maybe help someone decide if frequent plug changing is needed.

I don't think so, but here are the photos for you to decide.

for some reason had saved the original plugs that I had removed @ 12,500 miles,

so I took this comparison photo, and threw all away. [SIZE=8pt]My ‘04 bike now has 52,000 on it.[/SIZE]

FJRBluesman · May 22, 2010

They look PERFECT! Great color brownish gray. It's bruning well in that chamber.

Zorlac · May 22, 2010

Nice pics, I'll bet they still spark real good.

RadioHowie · May 23, 2010

The one thing you can't see in any of those pics is if the internal resistance of the plugs has changed. Visual plug checks are only one of the reasons to change plugs. YMMV.

escapefjrtist · May 23, 2010

Interesting Cecil. I just popped a set of Iridiums in the '06 this evening getting ready for Oregon. Plan on doing a TBS tomorrow while the tank is up.

I've been fairly religious about changing plugs & checking TBS every 8K, although the set I just took out had 12K on them. Plugs looked pretty sorry, gap was a loose .032 and well rounded. I'm hoping for a noticeable improvement with the new set.

--G

Bugnatr · May 23, 2010

RadioHowie said:
The one thing you can't see in any of those pics is if the internal resistance of the plugs has changed. Visual plug checks are only one of the reasons to change plugs. YMMV.

+1

3dogs · May 24, 2010

RadioHowie said:
The one thing you can't see in any of those pics is if the internal resistance of the plugs has changed. Visual plug checks are only one of the reasons to change plugs. YMMV.

If the plugs use an internal resister it's unlikely that its resistance would change over time/miles. Also, the real resistance in any spark plug is the air gap between the side and center electrodes. That will change over time as the electrodes "round" off or loose their square edges. That said, There is enough voltage available from the ignition coil on a wast spark system to easily overcome the change in resistance in the air gap.

Many automotive applications have plug change intervals at 100,000 miles (iridium or platimum plugs only) so there is no reason that the FJR's spark plugs whould be any different. I installed iridium plugs at least 25,000 miles ago and am still waiting for the engine to run crappy to indicate another plug change -- so far it still runs great with only a TB sync every 10k miles.

Afast03nNJ · May 24, 2010

3dogs said:
Many automotive applications have plug change intervals at 100,000 miles (iridium or platimum plugs only) so there is no reason that the FJR's spark plugs whould be any different.

Totally agree.

charismaticmegafauna · May 24, 2010

I once owned a Toyota Supra and was showing-off the (DOHC) engine to my, race machinist -- gearhead, buddy when he saw the header-panel sticker that read (something-like): "Fine-wire electrode spark plugs installed -- use only..."

He said, "Well, you can probably throw away your spark plug wrench."

3dogs · May 24, 2010

charismaticmegafauna said:
I once owned a Toyota Supra and was showing-off the (DOHC) engine to my, race machinist -- gearhead, buddy when he saw the header-panel sticker that read (something-like): "Fine-wire electrode spark plugs installed -- use only..."He said, "Well, you can probably throw away your spark plug wrench."

I had and 1986 Supra (very hot car back then) and was woundering how much time it was going to take me to change plugs (massive intake manifold in the way) until I saw the sticker that stated "Plug change at 100,000 miles". I never did change the plugs becuase I sold the car with about 80k miles.

Groo · May 24, 2010

I changed out the Iridiums I installed about 35K miles ago yesterday... they looked cleaner than yours, and though the bike was running fine before, and runs fine as of this morning, I guess it's as much a peace of mind thing...

I could dig them out of the trash when I get home and take a picture if anyone wants to see them...

David Morrow · Jun 13, 2010

I just replaced my old OEM plug with some more. According to my maintenance log, it's been 78,497 Km's or about 49,000 miles. They look the same as the pic's at the top; nice light brown.

But, it really isn't that big of a job and I have to remember that next time and not leave it so long.

UHOH · Jun 13, 2010

David Morrow said:
I just replaced my old OEM plug with some more. According to my maintenance log, it's been 78,497 Km's or about 49,000 miles. They look the same as the pic's at the top; nice light brown.

But, it really isn't that big of a job and I have to remember that next time and not leave it so long.

couldn't have said it better myself ... :thumbsup:

Longrider · Jun 14, 2010

I have run Iridium plugs since my 04 had 5000 miles. I keep track of MPG and when it drops do a injector balance. If that doesn't correct the MPG, I change plugs. At 63,000 miles I am on my second set of Iridiums.

Haven't done a long trip since joining the Dark side, but MPG before has always been 48 to 52 MPG.

Longrider

64Y80 · Jun 14, 2010

RadioHowie said:
The one thing you can't see in any of those pics is if the internal resistance of the plugs has changed. Visual plug checks are only one of the reasons to change plugs. YMMV.

I agree. I had a Roadstar with a 2 plug per jug design. The recommended plug change interval was 7500 miles. I thought that to be overkill considering the interval recommendation on my car, so I started stretching it. On my second set of plugs, at about 8000 miles I had a loss of power and a reduced idle situation (I know, I know, no tach, 54 hp how could I tell, just had my seat of the pants calibrated the week before so I could). Checked the plugs, the first 3, looked perfect, still had the proper gap, good color. The fourth plug gap was still good but color was all wrong telling me that it wasn't firing. I replaced all plugs and everything was good again. I suspect that had I checked all the plugs visually before the failure, all would have looked good, after all, all you can check visually is the gap and color, if firing color will be good on a healthy engine. Don't know what failed on the plug other than obviously an internal short developed, but now I tend to stick pretty closely to recommendations.

Windjammer · Jun 14, 2010

Many automotive applications have plug change intervals at 100,000 miles (iridium or platimum plugs only) so there is no reason that the FJR's spark plugs whould be any different.

Except for one thing - your FJR engine spins at higher RPM than most car engines, so your plugs are going to fire more times per mile compared to a car. 100K in the average car and 100K on the FJR would not be the same thing.

RaYzerman19 · Jun 15, 2010

Windjammer said:
Many automotive applications have plug change intervals at 100,000 miles (iridium or platimum plugs only) so there is no reason that the FJR's spark plugs whould be any different.

Click to expand...

Except for one thing - your FJR engine spins at higher RPM than most car engines, so your plugs are going to fire more times per mile compared to a car. 100K in the average car and 100K on the FJR would not be the same thing.

Car engines fire every other stroke, whereas most bikes fire every stroke due to their ignition setup (one coil for two cylinders).

FJRBluesman · Jun 15, 2010

Yzerman19 said:
Windjammer said:

Many automotive applications have plug change intervals at 100,000 miles (iridium or platimum plugs only) so there is no reason that the FJR's spark plugs whould be any different.

Click to expand...

Except for one thing - your FJR engine spins at higher RPM than most car engines, so your plugs are going to fire more times per mile compared to a car. 100K in the average car and 100K on the FJR would not be the same thing.

Click to expand...

Car engines fire every other stroke, whereas most bikes fire every stroke due to their ignition setup (one coil for two cylinders).

The coil may donate juice twice as often when sharing plugs; however, the individual plug(s) still only fire very other revolution (4-strokes {a stroke is each time the piston either goes up, or down}, two crank shaft revoltions)... unless you're talking a 2-stroke (one crank shaft revolution).

RadioHowie · Jun 15, 2010

FJRBluesman said:
The coil may donate juice twice as often when sharing plugs; however, the individual plug(s) still only fire very other revolution (4-strokes {a stroke is each time the piston either goes up, or down}, two crank shaft revoltions)... unless you're talking a 2-stroke (one crank shaft revolution).

There's just one little miscalculation in your treatise, Bluesy....it's not the fuel in the cylinder combusting that wears out plugs, it's the spark jumping the gap that wears 'em out, and the shared-coil design fires the plugs every revolution, so (theoretically) an FJR plug WOULD wear out in half the time a non-shared-coil design plug would. So while the plug only ignites the fuel/air charge every other revolution, on the compression stroke, the plug still fires across the spark gap EVERY revolution, compression and exhaust strokes, doubling the "wear out" speed.

Pics, iridium plugs after 24,000

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