Denso Iridium Power spark plugs.

The original 2-stroke Genuine scooter and its 4-stroke manual and automatic offspring

Moderator: Modern Buddy Staff

Post Reply
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Denso Iridium Power spark plugs.

Post by fullthrottle »

I just replaced the spark plugs in my Vespa PX150 and Genuine Stella scooters, with Denso Iridium Power spark plugs.

Too many good things to say about Densos. You can read all about them on their website:
http://www.densoiridium.com/ir_power.php

They do not need to be gapped.

I found out about them on a Maserati forum. Everyone there is doing it. I will eventually put them in all
my vehicles. Since I was purchasing a lot of different plugs, I bought them all at a good price from:
http://www.sparkplugauto.com/

But, if you just want to try one or two, you can find them on eBay.com or maybe your local auto parts store.

Both scooters now run better than ever. Idling is very smooth. They feel like they have more power, especially
the PX150, which used to bog down climbing hills. The top speed went from 60 m.p.h. to 65.

I'm also anticipating slightly better miles per gallon.

For both scooters, I did not use what the Denso website's "Find My Part" suggests, but instead used their
cross-reference with the spark plug numbers specified in the scooter's owner's manuals.

The Genuine Stella now has Denso IW20, part 5306.

The PX150 now has Denso IWF22, part 5379.

My Vespa Granturismo already has an NGK Laser Iridium I bought from scooterwest.com. That won't need to
be replaced for quite a while. Iridium plugs last a lot longer than regular plugs. Typically 10,000 miles.

Another good spark plug cross-reference is http://www.sparkplug-crossreference.com/

I also put a dab of dielectric grease on the spark plug post connecting to the wire.

Since this is an inexpensive upgrade for any scooter, I suggest everyone try a Denso. Since you only have one
spark plug, you may as well use the best. You will not be disappointed.
User avatar
BuddyRaton
Scooter Dork
Posts: 3887
Joined: Sat Sep 09, 2006 10:08 pm
Location: Boca Raton, Florida
Contact:

Post by BuddyRaton »

Duplicate post from disastrous thread on MV
http://modernvespa.com/forum/topic123894
"Things fall apart - it's scientific" - David Byrne
www.teamscootertrash.com

'06 Cream Buddy 125, 11 Blur 220, 13 BMW C 650 GT, 68 Vespa SS180, 64 Vespa GS MK II, 65 Lambretta TV 175, 67 Vespa GT, 64 Vespa 150 VBB 64 Vespa GL
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

Disastrous for some. Helpful for others, including myself.

Really, Raton? Now you're following me?
User avatar
stickyfrog
Member
Posts: 11
Joined: Sun Sep 28, 2008 5:46 am

Its a small world

Post by stickyfrog »

Betting it won't go much better here but I could be wrong.
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

Hi Sticky! Let's hope we have a quorum and not a quarrel.
Attachments
533-Vespa182.jpg
533-Vespa182.jpg (59.59 KiB) Viewed 2379 times
"I have a fear of speed bumps. But, I'm slowly getting over it."
fisher1
Member
Posts: 188
Joined: Sat Sep 08, 2012 6:45 pm
Location: Pa

Post by fisher1 »

Interesting stuff. What was the Denso's impact on your temps ... Did you benchmark the CHT or EGT before the plug change to see if the Denso resulted in hotter or colder running ? Also, were you using a NGK B7ES before or some other plug?

Thanks
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

No, I didn't do those measurements. But, I believe the Densos run a bit cooler, requiring less voltage.

Can you explain what you mean by CHT and EGT? I don't have much equipment, and I'm not an expert mechanic. And, I haven't modded my machines much, other than a few simple inexpensive things for better performance.

Before the switch, I was using ordinary, owner's manual recommended Champion plugs, properly gapped.

PX150 had RL82C.
Stella had RN9YC.

The PX150's plug always looked perfect, but the Stella's plug gets a bit oil fouled, as the previous owner up-jetted the carburetor, and I never messed around with it too much, other than cleaning it and re-gapping it once in a while. It runs slightly rich, but not the worst thing.

I'm selling the Stella anyway, along with some other accessories. (See my ads here in For Sale/Wanted.)

As the Denso website recommends, I didn't gap their plugs. You really don't need to, and it's easy to damage the tiny electrode. I didn't even check the gaps. I just dropped them in and they both worked perfectly.

It's pretty cold and snowing right now for more tinkering, but I will do some chops and inspect how the Densos look when we get some warm days.

From the Denso website:

"By harnessing the power of Iridium, DENSO is suddenly able to shrink the surface area of the center electrode - the critical component of a spark plug. Unlike a typical platinum plug that has a 1.1mm diameter center electrode, DENSO Iridium Power plugs have the world's smallest center electrode measuring 0.4mm in diameter. This means that the voltage requirements are decreased while firing performance is greatly improved."
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
BuddyRaton
Scooter Dork
Posts: 3887
Joined: Sat Sep 09, 2006 10:08 pm
Location: Boca Raton, Florida
Contact:

Post by BuddyRaton »

fullthrottle wrote:
Can you explain what you mean by CHT and EGT? I don't have much equipment, and I'm not an expert mechanic.
Cylinder Head Temperature and Exhaust Gas Temperature these measurements are critical for getting a 2T motor correctly dialed in.
"Things fall apart - it's scientific" - David Byrne
www.teamscootertrash.com

'06 Cream Buddy 125, 11 Blur 220, 13 BMW C 650 GT, 68 Vespa SS180, 64 Vespa GS MK II, 65 Lambretta TV 175, 67 Vespa GT, 64 Vespa 150 VBB 64 Vespa GL
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

I have two strong running 2T scooters, partly because I don't fool with them too much other than basic maintenance. I'll adjust the idle speed screw, and clean the air filter, but that's as much as I care to do in that regard. Both carbs are also clean as whistles.

The PX150 in particular never gave me one single problem in the 5 years I've had it, other than a blown fuse, and one burned out bulb.
"I have a fear of speed bumps. But, I'm slowly getting over it."
fisher1
Member
Posts: 188
Joined: Sat Sep 08, 2012 6:45 pm
Location: Pa

Post by fisher1 »

No, I didn't do those measurements.
Then you're flying (riding) blind my friend .... thanks for posts. It may be OK, but for now I'll wait and stick to the NGKs.
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

I have 3 scooters, 3 motorcycles, 2 cars and one truck and they're all running great. I don't do everything, but I do maintain these machines well.

And, I know enough now when to leave well enough alone. There is such a thing as failure due to maintenance, which I've had some regrettable moments with. I know what I can do, and when to see a real mechanic.

But, thanks for your opinion.
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
stickyfrog
Member
Posts: 11
Joined: Sun Sep 28, 2008 5:46 am

Post by stickyfrog »

Going well so far?
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

Absolutely. I'm very happy with all these machines. Just need to reduce the fleet a bit. I'll sell one motorcycle and one scooter, hopefully this spring. I may as well do it while they're running fine. The motorcycle is in nearly new condition.
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
jimmbomb
Member
Posts: 801
Joined: Fri May 20, 2011 1:00 am
Location: St Louis

Post by jimmbomb »

I think I'll try one in the P200... as soon as I can find a part number..
J H
[URL=https:///]Image[/URL] upload pics
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

First, get the spark plug number(s) from your owner's manual. Or,
if you don't have an owner's manual, see what plug you're currently
using. Get all the numbers you can for alternative recommended plugs.

Then, try the Cross Reference tab on the Denso site:
http://www.densoiridium.com/find_part.php

Or, this one:
http://www.sparkplug-crossreference.com/

Hopefully, they both say the same thing.

Like I said, I didn't go by the one Denso recommends for the Vespa PX150, but I used what their Cross Reference said instead. And then, I verified that with the other spark plug cross reference site.

Denso doesn't even list an iridium plug for the Stella, only a standard plug, so I could only find that by cross referencing. Denso's website lists plugs for many different cars and powersports, but it's not complete.

The Denso Iridium plug numbers all begin with "I". But, they also make standard plugs, too.

If you can't find a Denso Iridium plug to fit, an NGK Iridium may work equally well.

And, remember, you shouldn't need to gap them. Let us know how things turn out.
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
BuddyRaton
Scooter Dork
Posts: 3887
Joined: Sat Sep 09, 2006 10:08 pm
Location: Boca Raton, Florida
Contact:

Post by BuddyRaton »

No matter what plug you should ALWAYS check the gap.
"Things fall apart - it's scientific" - David Byrne
www.teamscootertrash.com

'06 Cream Buddy 125, 11 Blur 220, 13 BMW C 650 GT, 68 Vespa SS180, 64 Vespa GS MK II, 65 Lambretta TV 175, 67 Vespa GT, 64 Vespa 150 VBB 64 Vespa GL
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

Fine. Just don't damage the tiny electrode (.4mm).

It's very important to read this:
http://www.densoiridium.com/installationguide.php
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
az_slynch
Member
Posts: 1806
Joined: Wed Sep 12, 2012 4:56 pm
Location: Tucson, AZ

Post by az_slynch »

I'll preface my comments with two points on my own tuning habits:

1. I index the spark plugs on my two-stroke bikes. I once read that this was an old hot-rodder's trick for making a few extra horsepower in seriously high-powered engines. I don't think they make any measurable gains in my P200, the souped-up Stellas I've built, and most certainly not in any of the mopeds I've built. So why do I do it? Observations made on disassembly after a period of run-in seem to indicate that the engines burn a bit cleaner with the ground electrode facing away from the exhaust port. Due to the scavenging effect of a two-stroke, it seemed sensible to give the igniting mixture a clearer path to the exhaust port and let the incoming charge from the boost ports cool the ground electrode. So again, I do it to make my life easier when de-coking a two-stroke, not because it "makes more power".

2. I bought an iridium plug for my Kymco. The whole reason for doing so was to try and correct an issue where the idle "hunts" when then engine is cold. I have yet to install it. This was recommended by a guy on the Kymco forum who swore it fixed his idle hunting and made his bike 2mph faster. Before doing the plug, I installed a Simota high-flow filter on the bike; et voila, the idle hunt went away. So, the question is, was the plug necessary to correct it? In the same post, the guy made a minute valve adjustment as well. This throws ceteris paribus right out the window, as the plug wasn't the only change made. Loosening a tight valve can make top end power as well. I'll put the plug in, once I establish a performance baseline with the Simota filter installed. In order to see any tangible change from the plug, it must be the only change made to the bike's state of tune.

Now, on the topic of iridium plugs, I turned to Denso's FAQ:

http://www.densoiridium.com/faq.php

Let's just skip over the asteroid bit and look at the testing section. They reference a 5.0 Mustangs and Super Fords article. If we take the results at face value, they reported a 2-3hp gain in a normally-aspirated application, presumably from a 5.0L Ford motor. Your Stella has a .15L displacement, which is about one thirty-third of the displacement of said Ford motor. So let's say you do gain a little less than a tenth of a horsepower on your 8.3hp scooter. If you are used to little motors, you might notice the gain. However, it won't be much of a game-changer. You'll get more noticeable results with other , cheaper fixes, like removing the outer blue gauze from the air filter or drilling openings in the bottom of the filter on the cavity for the jet stacks. Those only cost your time, assuming you own scissors and a drill.

As for economy, you can realize that by closing the throttle about 1/8 from WOT. Speed won't decrease on a level road or minor grade. Ancient moped-rider's secret.

Lifespan? I got 10K on the last B6ES I put in my P200. I don't treat my bike like a princess. Perhaps an iridium may last longer, but I guarantee that I will service other things on that bike in a 10K interval, which would effectively nullify the one-change-only requirement in order to have a true comparison.

If the Denso does it for you, I'm glad you're getting your money's worth. I just ask that in touting them, remember that plugs alone don't make the bike.
At what point does a hobby become an addiction? I'm uncertain, but after the twelfth scooter, it sorta feels like the latter...

Seriously...I've lost count...

Seven mopeds ...that's still manageable...
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

Thanks for all that. Of course there's more to tweaking extra power from a two-stroke.

I also had removed the blue part of the air filter in my Stella, as well as the white plastic screen from under the seat.

I also back off about 1/8th from full throttle on the Stella. I discovered that on my own. There is a sweet spot where it has maximum power. Any more than that, it's just wasting fuel. My PX150, though, likes WOT for full power.

But those factors and and a few others were already done before I put in new iridium plugs.

So, yes. I do think I got all of my $7.50 per plug's worth already. I was surprised by it myself, but I did notice more power from both scooters but even more so in the PX150.

And, I will check the fuel economy closely in both scooters, and any other vehicles I put them in. And, I do expect a longer life of the Denso plug.

Good stuff!
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
az_slynch
Member
Posts: 1806
Joined: Wed Sep 12, 2012 4:56 pm
Location: Tucson, AZ

Post by az_slynch »

fullthrottle wrote:I also back off about 1/8th from full throttle on the Stella. I discovered that on my own. There is a sweet spot where it has maximum power. Any more than that, it's just wasting fuel. My PX150, though, likes WOT for full power.

Good stuff!
Between the Stella and the PX, it's all in the induction path. At high engine speeds, the Stella's reed is pretty much open constantly. The PX has the rotary valve built into one of the crankshaft lobes. Intake pulses only happen when the cutout in the crank exposes the crankcase to the intake. You could say that the Vespa has better mixture management at WOT.

Personally, I prefer the rotary valve. The power delivery feels smoother to me, but that's subjective.

On the other hand, a Stella with a Hot Reed and a re-jet isn't half-bad, either.
Last edited by az_slynch on Sun Jan 05, 2014 7:04 am, edited 1 time in total.
At what point does a hobby become an addiction? I'm uncertain, but after the twelfth scooter, it sorta feels like the latter...

Seriously...I've lost count...

Seven mopeds ...that's still manageable...
User avatar
fullthrottle
Member
Posts: 23
Joined: Fri Jan 03, 2014 12:21 am
Location: Philadelphia, PA.

Post by fullthrottle »

You're right. The PX150 is smoother and even sounds better. It's just better made in lots of little ways.

I do like the Stella, it's the first 2T scooter I bought. The previous owner had up-jetted the carb. It really pulls you.

But, I'm going to part with it anyway and get down to just 2 scooters and 2 motorcycles.
"I have a fear of speed bumps. But, I'm slowly getting over it."
User avatar
viney266
Member
Posts: 2270
Joined: Thu May 19, 2011 8:49 pm
Location: westminster md
Contact:

Post by viney266 »

I love my stella's but compared to the "high-tech" 2 strokes I have worked with they are old school farm equipment.

in the 80's we raced rz350's rz500's and a RS125 ( one of my employees). The iridium plugs had a HUGE difference in lifespan of a bike pushed to the limits. Even a run of the mill offroad bike ( 2 stroke) will see a much longer plug life from a iridium plug. They are in all my off-road bikes, and some of the really crazy built engines we had , indexing the plug DID make a difference, But. In my stella? I dunno. It likes its B8HS copper plug, it starts and runs fine. I replace the plug every couple thousand miles when I am doing other maintenance, just because they are $2.50.

I have thought about indexing it, just to see if I could find anything, but I haven't yet :)...platinum/iridium plugs? If you like them, use them, they sure won't hurt anything, and if nothing else they should last forever in a 2T.
Speed is only a matter of money...How fast do you want to go?
User avatar
BuddyRaton
Scooter Dork
Posts: 3887
Joined: Sat Sep 09, 2006 10:08 pm
Location: Boca Raton, Florida
Contact:

Post by BuddyRaton »

Plus at 2.50 a pop it doesn't break the bank to run chops
"Things fall apart - it's scientific" - David Byrne
www.teamscootertrash.com

'06 Cream Buddy 125, 11 Blur 220, 13 BMW C 650 GT, 68 Vespa SS180, 64 Vespa GS MK II, 65 Lambretta TV 175, 67 Vespa GT, 64 Vespa 150 VBB 64 Vespa GL
User avatar
viney266
Member
Posts: 2270
Joined: Thu May 19, 2011 8:49 pm
Location: westminster md
Contact:

Post by viney266 »

BuddyRaton wrote:Plus at 2.50 a pop it doesn't break the bank to run chops
^^^ VERY true.
Speed is only a matter of money...How fast do you want to go?
User avatar
srbbnd
Member
Posts: 223
Joined: Fri Feb 07, 2014 1:52 am
Location: Butt F@#$ No Where Missouri

Gapping?

Post by srbbnd »

Gapping? Picked up a new spark plug and gapping tool, been about 4,000 miles. What is the proper distance to gap for a Stella 4T?
Image
User avatar
Johnny O
Member
Posts: 71
Joined: Fri May 16, 2014 7:37 am
Location: NE Ohio

Post by Johnny O »

According to the service manual 0.7-0.8 mm. Unless you are looking for what denso might recommend.

Back when I noodled with import autos in the 90's I remember contacting Denso about gapping. I recall them e-mailing me that their plugs don't need gapped when purchased for specific applications. This may not apply but I wouldn't mess with it unless you are having issues after running for some time.
Post Reply