Author Topic: Spark Plug? 78 cb750 ? about Nippon X24ES-U (Read 11836 times)

luder · « **on:** August 19, 2009, 05:05:39 PM »

I was just looking for input. I forget who it was but something was brought up about replacing your spark plugs (D8ES) with a Nippon Denso X24ES-U. because of the difference in gas now days. Any input on this? Who has tried it, I guess they burn a little hotter.....thanks luder

Simpson · « **Reply #1 on:** August 19, 2009, 09:09:27 PM »

I believe Hondaman made that suggestion"
Just to throw out another question...
Would a hotter NGK work the same D7EA?

HondaMan · « **Reply #2 on:** August 19, 2009, 09:44:04 PM »

The X24ES-U is the same heatrange as the D8ES-L, which was discontinued in the late 1990s. It is halfway between the D7E and D8E in heat, and it has an extended tip to keep them cleaner. It was designed expressly for the CB750 engines.

Starting on the late 1990s, the EPA removed MTBE from our gas and started forcing everyone to use alcohol derivatives like ethanol instead. This makes a requirement for more spark plug heat because the ethanol does not light off so easily. An extended tip, along with (in the case of the ND plugs) a thinner ceramic end, makes the tip hotter without making the engine hotter: you will find the engine and oil temps to be LOWER with the X24ES-U plugs than with the D8EA. The D7EA will make everything hotter.

Flying J · « **Reply #3 on:** August 19, 2009, 10:13:48 PM »

who sells these plugs? i can get ngks from my local car parts store. do i need to go to a bike shop for these?

GammaFlat · « **Reply #4 on:** August 19, 2009, 10:37:47 PM »

Quote from: ffjmoore on August 19, 2009, 10:13:48 PM

who sells these plugs? i can get ngks from my local car parts store. do i need to go to a bike shop for these?

Go to www.amazon.com then search for X24ES-U. They're 1.65 - not sure on shipping.

B.O.X.N.I.F.E. · « **Reply #5 on:** August 19, 2009, 10:42:28 PM »

Recommended in a 550? Doing a long road trip and am worried about engine temp with prolonged use of the D7's

luder · « **Reply #6 on:** August 20, 2009, 06:10:00 AM »

Thanks Hondaman-perfect explanation....luder

Simpson · « **Reply #7 on:** August 20, 2009, 06:17:20 AM »

Thanks Hondaman! I like all the details, and you seems to have them.

Ordering plugs now.

Simpson · « **Reply #8 on:** August 20, 2009, 06:23:45 AM »

Quote from: simpson on August 20, 2009, 06:17:20 AM

Thanks Hondaman! I like all the details, and you seems to have them.
Ordering plugs now.

Went to amazon and ordered them already! internet is a wonderful thing.

HondaMan · « **Reply #9 on:** August 20, 2009, 06:57:56 AM »

Quote from: B.O.X.N.I.F.E. on August 19, 2009, 10:42:28 PM

Recommended in a 550? Doing a long road trip and am worried about engine temp with prolonged use of the D7's

We always switched the D7 to the X24 when touring on 500/550 bikes, until the 55 MPH speed limit came into being. Then, it didn't seem to overheat the 500 (I had one of them at the time) at 55, so we only changed them if the customer requested it after that. Today, at 70 MPH, I'd recommend the X24 again, for sure. I run them in my 750 all the time, and in all the bikes I build or service. They boost the midrange torque a little because of the U-shaped ground electrode, which lets the fuel mix flow a little better through the spark: on the 750K engines (swirl charge heads) this ignites a wider swath of the moving mixture during the 1.5mS long spark (Honda coils).

Duke McDukiedook · « **Reply #10 on:** August 20, 2009, 07:31:20 AM »

or http://www.sparkplugs.com/

luder · « **Reply #11 on:** August 20, 2009, 07:53:54 AM »

I ordered some and my Car Quest brought me out some Champion Plus PLU 809, None of my suppliers handle Nippon, I sent them back maybe I shouldn't have, any thoughts on cross reference and use....luder

HondaMan · « **Reply #12 on:** August 20, 2009, 03:49:07 PM »

Quote from: Dukiedook on August 20, 2009, 07:31:20 AM

or http://www.sparkplugs.com/

I just bought 2 boxes, right from these guys! Not the cheapest, but in stock and at my house in 4 days.

FunJimmy · « **Reply #13 on:** March 20, 2015, 09:34:43 AM »

Quote from: HondaMan on August 20, 2009, 06:57:56 AM

Quote from: B.O.X.N.I.F.E. on August 19, 2009, 10:42:28 PM
Recommended in a 550? Doing a long road trip and am worried about engine temp with prolonged use of the D7's

We always switched the D7 to the X24 when touring on 500/550 bikes, until the 55 MPH speed limit came into being. Then, it didn't seem to overheat the 500 (I had one of them at the time) at 55, so we only changed them if the customer requested it after that. Today, at 70 MPH, I'd recommend the X24 again, for sure. I run them in my 750 all the time, and in all the bikes I build or service. They boost the midrange torque a little because of the U-shaped ground electrode, which lets the fuel mix flow a little better through the spark: on the 750K engines (swirl charge heads) this ignites a wider swath of the moving mixture during the 1.5mS long spark (Honda coils).

HondaMan

This is great info. You have an amazing amount of technical knowledge and I appreciate you sharing it with us. I have a hot little CB550 with electronic ignition and the ignition manufacturer recomends resistor plugs. Would you suggest the Denso X24EPR-U9 as the resistor equivalent to the X24ES-U for this application? How about the Iridium IX24B? Do Iridium tipped plugs offer any advantage?

Thanks
Jimmy

PeWe · « **Reply #14 on:** March 20, 2015, 01:17:44 PM »

The plug caps are also involved. 5 kOhm caps - no resistor plugs recommended.
http://forums.sohc4.net/index.php/topic,30938.msg1640877.html#msg1640877

I have caps with about 5Kohms. I use NGK D8EA. I have also used Denso X24ES-U
~~CB550 should use warmerplug than CB750, right? NGK D7EA~~
Edit. Sorry, saw later that this is only about CB750

Wobbly · « **Reply #15 on:** March 20, 2015, 02:09:25 PM »

FunJimmy · « **Reply #16 on:** March 20, 2015, 02:55:26 PM »

I didn't realize Denso has a X24ESR-U.
I assume the "R" refers to a resistor version.

Thanks

Wobbly · « **Reply #17 on:** March 20, 2015, 02:59:06 PM »

Quote from: FunJimmy on March 20, 2015, 02:55:26 PM

I didn't realize Denso has a X24ESR-U.
I assume the "R" refers to a resistor version.

Thanks

Yes--standard for European and Canadian models.

Garage_guy_chris · « **Reply #18 on:** March 20, 2015, 04:42:04 PM »

The Plugs are available through www.rockauto.com use the part number search tab and pump in the Denso number and select Denso as the manufacture.

Right now there a whole $1.88 each. next time I order from them Im gonna toss on a bunch of these for my 750 and the w24es-u's for my 450

Oh and here's there specification chart decoder thing for the Denso's.

http://www.globaldenso.com/en/products/aftermarket/plug/spec/index.html

HondaMan · « **Reply #19 on:** March 20, 2015, 07:15:48 PM »

Quote from: FunJimmy on March 20, 2015, 02:55:26 PM

I didn't realize Denso has a X24ESR-U.
I assume the "R" refers to a resistor version.

Thanks

I think their correct number is XR24ES-U.
Here's a little more detail for the stickler (like me!) out there:
the OEM sparkplug caps on the bikes from 1969-1974 were 7500 ohms. After that they were 10,000 ohms. Higher ohms (with ANY coil) makes a longer-duration spark, which these bikes will always thank you for, with more midrange torque. Today, we can come closest to the OEM setups by running BOTH the 5000 ohm plug caps AND the 2000 ohm resistor sparkplugs (most resistor plugs are 2000 ohms), which several here have reported causing their bikes to start and idle easier, right from the start.

If you have low-ohm primary coils (less than 4.0 ohms), it is imperative that you use the high-resistor plug caps lest the coils generate extra heat and have a VERY short spark. When Honda switched to the 10,000 ohm caps, this was accompanied by a lower-ohm primary coil: the 1969-1974 coils were 4.6 to4.7 ohm primaries, while the later ones were 4.3 to 4.4 ohms. This ratio corresponds to the slightly hotter, but shorter duration, spark. So, they used 10,000 ohm plug caps to stretch the spark duration out a little bit more. This was done mostly to increase the early burn cycle so as to reduce hydrocarbons at the exhaust pipe, but the result was that the plug caps on the later bikes burn out sooner because they run much hotter than the 7500 ohm (or today's 5000 ohm) types.

Since the swirl-charge design in these engines makes the most of the longer spark duration, giving it will make for a nicer ride, especially at speed.

PeWe · « **Reply #20 on:** March 22, 2015, 07:18:02 AM »

I have today NGK D8EA with Dynatek wires, DW-1200 Grey siilicone, 8mm graphite suppression core. I measured each wire around 5 kohms. Dyna 5ohms coils, TEC points and Hondaman ign module.
I'll try resistor plugs like the expensive NGK Iridium DR8EIX when I have adjusted the carbs. Maybe Dyno test before and after plug change so I'll know.

FunJimmy · « **Reply #21 on:** March 22, 2015, 07:35:10 AM »

Quote from: PeWe on March 22, 2015, 07:18:02 AM

I have today NGK D8EA with Dynatek wires, DW-1200 Grey siilicone, 8mm graphite suppression core. I measured each wire around 5 kohms. Dyna 5ohms coils, TEC points and Hondaman ign module.
I'll try resistor plugs like the expensive NGK Iridium DR8EIX when I have adjusted the carbs. Maybe Dyno test before and after plug change so I'll know.

That would be great. I'm interested to see if it's measurable on a dyno.

bwaller · « **Reply #22 on:** March 22, 2015, 08:07:41 AM »

Jim, try IX24's with 5K ohm caps. I attempted on a dyno to prove worth of 1st) indexing plugs 2nd) regular vs Iridium and finally NGK vs Denso. Nothing in it unfortunately. I do use the IX27 in my race engine and prefer them over any others.

FunJimmy · « **Reply #23 on:** March 22, 2015, 08:55:14 AM »

Thanks Brent. I'll give them a go.
Just out of curiosity, why IX27 in the race bike?
Aren't they too cold?

bwaller · « **Reply #24 on:** March 22, 2015, 09:18:50 AM »

No, I was using D9's, then NGK Iridium, finally IX27. Colder plug needed for racing.

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Author Topic: Spark Plug? 78 cb750 ? about Nippon X24ES-U (Read 11836 times)

Wobbly

Wobbly