Kind of sparkplugs?

[Tompasio]

My GSX 750 ES -83,are by the manual having NGK Plug, D8EA or DR8ES-L,
What are the diffrences between these plugs? Exept the DR are resistorplug.

[mriddle]

It would be the resistor and one half step up in heat range (colder).

http://www.kaila.net/tl125/tl125ngkcode.html

NGK Sparkplug Codes

Following is a brief list of various codes found in the NGK spark plugs. This is actually a copy of a document that used to be on the Motorcycle Tuning Resources page. Those pages are apparently down so I decided to post the codes here on the TL pages.
Example NGK codes: [P] [6] [E] [S][D] [8] [E] [S] [-] [L]
Field one: Thread DiameterA18 mmB14 mmC10 mmD12 mm
Field two: ConstructionCHex size 5/8"KHex size 5/8" with projected tip (ISO)MCompact typePProjected insulator typeRResistorSDSurface discharge for rotary enginesUsemi-surface dischargeZinductive suppressor
Field three: Heat Range2Hottest10Coldest
Field four: Thread reachE19 mmFtapered seatH12.7 mm (1.5")L11.2 mm (7/16")If this is blank, an 18 mm diameter plug has 12 mm reach; and a 14 mm plug has 9.5 mm (3/8") reach.
Field five: Firing and constructionA,BSpecial design (no details given)Cspecial ground electrodeGRacing useGVRacing V-typeHHalf thread K2 ground electrodesLHalf heat rangeLMCompact lawn mower typeM2 ground electrode for Mazda rotary engineNSpecial ground electrodePPlatinum tip (premium)Q4 ground electrodesRDelta ground electrode for BMWSStandard 2.6 mm electrodeT3 ground electrodesVFine-wire electrode, gold-palladiumVXPlatinum tip (high performance)WTungsten electrodeXBooster gapYV-groove center electrode
[B]Field six(after the dash): Wide gap8.032"9.036"10.040"11.044"13.050"14.055"15.060" 20.080"LHalf heat rangeNSpecial ground electrode (note: appears to be limited to BMWs) This info also came from Yahoo .. Best Answer - Chosen by Asker

Half Heat Range means,,,The Heat Range is Half.


Seriously,,,,it's an Odd specification.

Spark Plugs perform a Self -Cooling function by conducting Combustion Heat Away from their Firing Tip>up into the Plug's Body>then Out into Cylinder Head,,,and ultimately out into the surrounding air.

All that journey is called Heat Path.

The Plug Depends upon Certain,Specific Temps to operate most efficiently.
If Too COLD,,it wont Fire reliably,,and will be prone to Fouling.
If Too HOT,,,it's tip will Glow like any Heated Metal which can ignite the Fuel/Air Charge Before the Plug actually Sparks.
That can not only cause serious engine damage,,,it's also a Warning Sign of engine Overheating due to various faults.

The Rate of Self-Cooling of the Plug is called "Heat Number",,or "Heat Range"

Example: DR6ES,,DR7ES,DR8ES,DR9ES,,,,are All Identical Except for their Rate of Cooling.

In that example,,DR6ES is a comparatively "Hot" Plug.
It's Rate of Self-Cooling is SLOW,,,allowing Engine Heat Input to RISE Higher in the Plug

DR8ES is comparatively COOLER,,,,
It Transfers Combustion Heat thru itself and Out the Heat Path FASTER,,,before it can raise Plug Temps very high.

The Terms "Hot Plug" and COLD Plug" are all about How Long it takes for the Plug to trnsfer ENGINE HEAT.

Nothing about the PLUG Itself GENERATING Heat.

Each Number is "1 Heat Range".
A 6 is 1 Heat Range Number "Hotter" than a 7.
A 9 is 2 Heat Range Numbers "Colder " than a 7.

The Idea of Half Heat Range is simple.
It's exactly what it implies,,, Halfway between 2 "normal Numbers".

A DR8ESL is a "8.5",,,Halfway to being a "9".

It's Splitting Hairs in my opinion.
NGK Plugs in particular have an unusually Wide Temp Range per given Heat Number.
As much a 2~3 Numbers are covered,compared to some other plugs.

If an "L" coded Plug is working fine,,,,You should be able to use a Heat Number on "either side of that" and do just Fine.

(Hotter)<<< DR8ES<<<< DR8ES-L>>>>>DR9ES>>(Colder)

That's all compatible/Comparable...but it IS a Change.
Selection of which way to go should be based on engine operation characteristics to ,,Hopefully,, Gain any advantage of that 1/2 Number change

Example,,in Summer You may want a Colder Plug,,in Winter a Hotter one.
Or if going to different Climate or Elevation.


Is the Mud starting to feel like Concrete hardening yet??

Biggest Point is,,,as far as Right or Wrong,,
An "L" coded Plug can be Considered Same as it's Heat Number,,,and the "Half Step" Disregarded.

Simply Put,,Both are "Right",,Neither are Wrong,,they're are approximate Equivalents.

In Fact,,they are Closer to being Identical than if You'd Cross-Refference to a Different Brand of Plug.

An "Exact Replacemnt Plug" in a Different Brand has a bigger difference than what exists between L and Standard.

Hope that helps

[Hoges]

Got the same motor and run with NGK D8EA. Nil problems with these over last 15 years of ownership.

[Steve]

Thank you, mriddle.

I was merely going to say that they were almost the same, and thought the L was a longer tip, but I see that I would have been wrong.

I also appreciate the emphasis that a spark plug does not control the temperature of the engine. Installing a colder plug does NOT cool the engine.
Actually, if you install too cold a plug, it will foul out and won't fire, then the engine will stay cool because it won't run.