Krip,,,
The Difference in those 2 plugs is the "5" suffix at end of plug number.
What that specific "code number" signifies on all NGK plugs is that it is a
PRE-GAPPED PLUG,,,
with the Gap Pre-set according to Factory Specs for the particular application.
The number is actual gap specified in mm's,,,
"5" would indicate a 0.5mm gap.
Which is about .019~.020"
So , Except for the "-5" being Pre-Gapped to 0.5mm,
BR9-ECS is IDENTICAL to a
BR9-ECS-5.
The ACTUAL Difference is .004" / .01mm in Gap
NGK's standard gap is .024"/.51mm
.................................................
Here's the deal on Plugs
NGK letters their Plugs Primarily according to:
DIAMETER>>HEAT RANGE>>LENGTH
Your Plug is "generically " a B9E,,,thats the BASE Number
#1 Priority is that a plug be a Physically Correct FIT
--that includes
a)Thread Size
b)Length
c)Seat /Gasket Type
The plug number's 1st character is THREAD size
"B"=14mm
Then "E"= 3/4" length
#2 Priority is HEAT RANGE
The Number "9" is the heat range.
If a Plug FITS properly,,
and is APPROPRIATE Heat Range(note I did not say CORRECT,or RIGHT)....
Then It's Fine for your motor.
All the OTHER Numbers & letters included are additional Details of OPTIONAL Features,Construction,etc.
B"R"9xxxxx
R=Resistor,,,,for example.
In "purest sense",,,
in terms of whether or not it's Safe,,will Run,,not hurt anything,,and so on...
It does NOT matter if the "R" is there or not.
"C" indicates Tip Configuration
"S" indicates Electrode Type
"5" indicates Pre-Gapped size
In the exmple of code letter P,,,which is NOT part of your plug's specs ,,,,,
"P" = Projected Tip,,the Tip Protrudes abnormally far out the end of the Plug.
As far as interchangeability and PHYSICAL ,Dimensional SAFETY-----this is the Only Cautionary Exception.
Many,Many Engines CAN tolerate a P plug,,,,
SOME engines cannot because of mechanical interference.
Other engines Cannot because it places plug too close to piston creating a local Hot Spot which at Hi Speeds can cause problems.
All those things are DETAILS of Optional characteristics,,special features etc,,,,
for purpose of OPTIMIZING a Plug for a Specific Application.
Consider it all like,,,Coca-Cola for example.
You cannot bring Glass Bottles to a public event,,,so Plastic or Cans are Ideal.
You may stock 2 or 3 Litre Bottles at home to serve in glasses.
But if you had a Big Party orSocial Event,,You may want to rent a Soda Fountain to serve Gallons
There's Diet,Caffeine Free,Cherry Coke,etc.
All DETAILS to optimize the Product for the Specific APPLICATION.
Yet,,it's ALL Coke.
Point is,,,Understanding that Plugs have a BASIC set of specs as well as a Bunch of Optional Features,,,
It strips away much of the VooDoo Myths about Plugs.
If you ever find yourself Stuck somewhere with a fouled plug,,,,and the "Perfect,Ideal,Exact Plug" is NOT available,,,
Odds are Excellent there's a BUNCH of plugs which will get you home,,,or "save the weekend outing"
The Plug MUST fit properly---
yet,,there's even "Dire Emergency Exceptions to That RULE".
And the Heat Range SHOULD Be "CLOSE".
Any engine except the most Highly,FINELY Tuned Racers being run HARD will happily tolerate +/- at least 1 Heat Number.
Your engine for example,,,it would scarcely know the difference between a
B9xxxxx
B8xxxx
B10xxxx
I worked for Bombardier years ago,CanAm M/C division.
Bombardier is NOT foolish enough to put a Consumer Product in the field which Lives or Dies according to 1 Heat Number difference in it's freakin' Spark Plug.
Not by a Long Shot
Neither is any other manufacturer,,,none that I know of anyway.
"Wide Range" heat range coverage is actually NGK's original Engineering and Marketting Distinction vs it's competitors back in the day.
1 NGK heat number would cover 2~3~sometimes 4 Champs,A/C's,Lodge,KLG,Autolite,Bosch,etc
.............................
On YOUR Plugs,,,,,they are 14mm,,3/4" Reach,,COOL Plugs
(NGK's 9 is a relatively Cold Plug,,only 10's and 11's are Colder---most Bikes run 7's and 8's,,,Hi-Perf bikes run 8"s and 9's,,,car's run 5's~6's)
NGK BEGINS Your Plug as a "B9E"
They NAME it a "B9ES"
S=Standard Electrode
Then they begin Adding different combos of Features
The Resistor,,,it becomes a BR9E-S
b>R<9es
A special nose shape... The S is Dropped in place of C,it becomes BR9-EC
br9e>C<
Then they PRE-Gap it to the applications specs..
br9ecs->5<.
So beyond Both plugs you mention being merely "Dressed-Up" plain 'ol B9ES plugs,,
They're actually Identical,,,other than the Pre-Gap setting.
It's a "Consumer Convenience Feature",,,but even NGK themselves Suggest that End Users CHECK the Gap,,,and Re-Adjust if necessary.
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
As far as Technically "Same/Comparable/Cross-Reffed" Plugs for YOUR SkiDoo....
Denso-- has 22 different #'s for "same plug" for You engine
NGK-- has 56
Champion-- has at least 12
Splitfire-- has at least 6
Autolite-- has a Bunch
Bosch has several
Thats well over 100 plugs which are technically CORRECT for your motor.
Not counting the +/- 1 Heat Number possibilities.
That would be Over 200 "Different" Spark Plugs Technically Compatible with your engine.
Granted,,,I doubt You'd want to pay $40~50 EACH for several of those.
(NGK 2780 R5883-9 $68.95,,for example )
And Most of them are indeed a Less-Than Ideal Combination of Additional/Special Feautures to be Optimum for Your sled.
But by same token,,,even the Factory Spec'd Plug ITSELF is a Compromise combo of features & specs deemed suitable by Bombardier.
The "C" nose configuration for example,,,
That's one of the OLDEST modifications to basic plug design to improve performance in 2 Strokes.
It's a 50 Year Old+++ "Spark Plug" trick..
Lots has evolved in Engines,Oils,Fuel,Metallurgy,Electronics ,2 Stroke Tech,etc since WW2.
The fact that the C-Nose remains effective today,,is pretty remarkable.
Even if it is a half CENTURY Old "technology".
To Equal or Exceed the C-Nose Results via employing Modern Technology would reqire a plug 3 Times the Price.
EASY to Beat an ol' C,,,,,,,,,but NOT for the money.
Mfgrs are reluctant to saddle their products with Unnecessarily expensive parts.
Part of that reluctance is a Logic that an engine Should Run Fine & Normal on a "Plain Standard" Plug.
If NOT,something is WRONG and a "FANCY ,Expensive Plug" is NOT the Solution.
The use of a Specialized Plug is thereafter an ENHANCEMENT,,,,and NOT just a halfazzed PATCH for sloppy engineering and poor development work.
The MFGR's always select OEM plugs according to their own Corporate Agenda.
That gives CONSUMERS who sorta "coat-tail"-along on Factory/Book Specs ,,,,a wide range of various assurances.
But in NO WAY does that include any assurance of Factory Specs being IDEAL,,,they seldom are.
In a very large percentage of instances it's quite possible to Beat the Factory Specs.
ALL the factories Themselves know that.
Many will even go as far as stating a small Variety of Plugs which are suitable,,,
as well as some Alternatives to suit different applications/conditions.
.................................
In any case,,,the 2 plugs you asked about are The Same.
It's Not Colder,or Hotter
It wont make your CARBURETTOR deliver Less Fuel causing a Leaner Mixture
Wont cause you to go cross-eyed,
or grow hair on your spark plug wrench,
or any other such nonsense.
..........................................................
The SOLE difference is about .004" Plug gap.
The differences in production tolerances of plug gap gauges,,,,and Users "interpretations" of the feel of the gauge in the gap can amount to as much as HALF that .004 difference between the 2 plugs.
As Little and inconsequential difference as .004 is,,,
In Real World averages it's probably even Less than that.
If you happened to Check the gap and set it to factory specs,,,,then there's No Difference whatsoever.