sparkplug question, likely a simple answer

[zio]

Read this from Dirt Bike mag's website:

Dear Mr. Know-it-all,
The spark plug suzuki recomends for my 2001 RM125, an r6918b-8, cost 20 bucks. i've been running a br8es without any problems.what is the difference in these plugs and what can possibly justify charging twenty dollars for a spark plug? Thaks for your time.
lu449@yahoo.com - 4/4/02 1:20:18 PM

A. Unfortunately, the recommended plug works best with the RM125. Yes, you can get away with the BR8ES but your performance suffers slightly. I talked with Cole Gress the Amateur Support Manager at Suzuki and he told me that the higher priced plug emits stronger spark with a longer duration and that it needed for optimum power on the RM125. Sorry.

Now- does a spark plug regulate the amount of spark, or does the ignition? I know plug gap & heat range play a part, but not sure if a different aftermarket NGK or Champion couldn't fit the bill here. I remember discussions on acceptable alternatives to the Suzuki plug, but nothing like this that claims the stocker is best. Mr Know-it-all didn't know the answer (ha!), but I don't doubt for a second that I'll get it here.

 

[skhasky]

"emits stronger spark with longer duration" - Magic Spark Plugs! The coil and the gap affect these things. Magic Spark Plugs my ass... send this email to NGK. You WILL get a straight answer. Mr. No-It-All should change his name to Mr. If You Can't Dazzle Them With Brilliance, Baffle Them With Bull****. I wonder if he ownes stock in these Magic Plugs...

 

[skhasky]

Ok.. now that I have calmed down a bit... Spark Plugs. The Ignition sends a signal to the coil triggering it to discharge. The duration is controlled by the Ignition. The spark plug is actually very simple. All plugs are created relatively equal, and they all do the same thing. The 'strength' of the spark is determined by the gap. Too little gap, and you get inefficient burning. Too much gap and you overload the coil. The temperature of the plug is regulated by the insulator length. The longer the insulator, the hotter the plug - meaning that the insulator will retain more heat and bring the insulator temperature up as well as the cylindar temperature. Other than that.... the plug must have the right thread, sealing design, and depth for a given application. Now, some manufacturers produce thin wire or Platinum/Gold/Iridium plugs and such. These are more conductive than lesser metals, and are therefore more efficient. They are designed to be used with lower powered electrical systems. Also, since the tip is thinner, they produce a more concentrated spark. At most, the difference between standard and platinum is 1 to 1 1/2 % - tops! And if the mixture is burning completely to begin with, it is a waste of money since there will be no improvement. If in doubt, use the BR8EVX plugs or comparable platinum of the same heat range specified by the manufacturer. The best precious metal / thinwire blugs by NGK, Champion , Autolite, etc.. will perform on-par with each other. There is no magic here, just marketing. At the top level, they are all equal.

 

[zio]

Originally posted by skhasky
Magic Spark Plugs my ass... send this email to NGK. You WILL get a straight answer.

Done. I'll post their response when it comes in. Thanks!

 

[zio]

Got a great response from NGK- read on:

Hello,

Thank-you for your recent inquiry about the Suzuki RM125 and the recommended
spark plugs for this application.

First I would like to explain why the R6918B-8 is so expensive. This
particular spark plug was designed and engineered for this specific
application. Due to the fact the production volume is lower and the number
of spark plugs sold is much lower then that of the BR9ES, the cost of the
spark plug is increased. The production costs and the fact this spark plug
utilizes gold palladium, a precious metal the cost is much more.

The Suzuki RM125 is a high revving, high compression engine and has
vibration issues throughout the power band. We've tested with Suzuki and
found the ES, EG, EV and EGV and determined these spark plugs fail under
certain loads and conditions. If you compare the two spark plugs you'll
notice a major difference in ground electrode design. The R6918B has an
electrode designed to withstand severe vibration and possible detonation
associated with these bikes. A standard spark plugs ground electrode is
welded on the outside of the metal shell and can vibrate like a tuning fork
throughout certain rpm ranges. This severe vibration causes fatigue and the
ground electrode fails. This is why the R6918B was chosen for this
application. The R6918B is very reliable and durable in these conditions.
Ignitability with this spark plug is better then the ES series due to the
diameter of the center electrode. Any time you have a racing engine you
need to choose a spark plug designed to withstand this type of environment.

I would also like to inform you I am the person who takes care of damage
claims at NGK Spark Plugs. I have had more BR8ES and BR9ES spark plugs
cross my desk every month with broken ground electrodes and receipts for
repairs. When the ground electrode fails it bounces around leaving
indentations in the cylinder head and the top of the piston. If your lucky
the ground electrode will sneak out of the cylinder, however if your not the
ground electrode wedges itself between the piston and cylinder wall and
intern destroys the engine.

I hope I have helped you in better understanding why this spark plug is used
in this application. If you have any questions or concerns please feel free
to contact me at (248) 926-6900 ext 248.

Sincerely,

Jon MacQuarrie

Jon MacQuarrie
Technical Customer Service Representative
jmacquarrie@ngksparkplugs.com




-----Original Message-----
From: webfeedback@ngksparkplugs.net [mailto:webfeedback@ngksparkplugs.net]
Sent: Tuesday, April 09, 2002 5:04 PM
To: info@ngksparkplugs.com
Subject: Tech Info Feedback


VehicleType: motorcycle

Make: suzuki
Model: rm125
Year: 2002
Engine Type: single cyl., 2-stroke 125 cc
Comments: I read this comment on Dirt Bike magazine''s website and
basically didn''t believe what I read.

"Dear Mr. Know-it-all,
The spark plug suzuki recomends for my 2001 RM125, an r6918b-8, cost 20
bucks. i''ve been running a br8es without any problems.what is the
difference in these plugs and what can possibly justify charging twenty
dollars for a spark plug? Thaks for your time.
lu449@yahoo.com - 4/4/02 1:20:18 PM

A. Unfortunately, the recommended plug works best with the RM125. Yes, you
can get away with the BR8ES but your performance suffers slightly. I
talked with Cole Gress the Amateur Support Manager at Suzuki and he told
me that the higher priced plug emits stronger spark with a longer duration
and that it needed for optimum power on the RM125. Sorry."


Can you shed some light on this for me? I''ve always ran your BR8EG plugs
in most of my bikes, occasionally running the BR7 or BR9 & never once had
a problem with them. My basic understanding of spark plugs & ignition
systems is that the ingnition, plug gap & insulator are what determine
spark duration, strength, heat, etc. So how can this guy claim that their
$20 plug is better than a $2.50 plug from NGK?
When: 4/9/2002 5:04:11 PM
Used Part Finder: 0

 

[RM_guy]

Very professional response from NGK. This is identical to what Eric had told me in the past. I was going to respond but decided to wait until you got your response from NGK.

 

[jmics19067]

ahhhh yes I always love the story of harmonics. It is quite an amazing thing , reminds me of the suspension bridge Galloping Gurdy.

The cost and reasoning sounds very realistic to me now. I wouldn't think Suzuki would pay the extra money to have a specific spark plug designed for them if they didn't feel the need. They must have designed and tooled for production this particular engine and found out about a wierd failure. Then try and save it.

 

[Vic]

The thing is, these special plugs have been spec'd for both the RM 125 and 250s for several years now. The failure rate of the regular plugs may be due more to people running the same plug for too long than anything else.

 

[RM_guy]

Originally posted by Vic
The thing is, these special plugs have been spec'd for both the RM 125 and 250s for several years now. The failure rate of the regular plugs may be due more to people running the same plug for too long than anything else.

I agree with Vic. If you change your plug frequently you're probably OK. I use a BR8ES in my RM250 and change it every time I do a top end job at 30 to 40 hours.

 

[David Trustrum]

It amazes me that the NGK rep has made a fundamental error in his reply.

If your lucky the ground electrode will sneak out of the cylinder, however if your not . . .

He should have said If “you’re” lucky . ..etc . . however if “you’re” not . . .


OK that silliness aside

I will add that if you are on the edge of combustion, ie you are running a silly high compression ratio on an average ignition then the more efficient spark of a fine wire plug will allow better combustion thus more hp in this situation.

I have seen on the dyno a B9ES outperform a fine wire plug in a particular bike.

I have seen a fine wire plug add a full hp on a 10hp 50cc.

I have also seen to my initial disbelief a NGK racing plug similar to the type described add a ½ hp over a fine-wire plug (also on a 50cc). But on the same type of engine make no difference.

The difference between the bikes was the head was very shallow on the bike that got the improvement & the std fine wire was shrouding the spark. Well that’s the theory we came up with.

In most instances doubt power would be affected though. Was aware of the vibration issue though.

 

[jmics19067]

In most instances doubt power would be affected though. Was aware of the vibration issue though.

woudln't it be ironically funny if Suzuki by chance got a bad bunch of plugs that they tested on their engines during designing?

just out of curiosity though a question to someone with an engineering degree that deals with vibration. Wouldnt the ground strap/prong on the plug have a different harmonic from plug to plug? Would quality control of the manufacuring of the plug be certain that every strap/prong was exactly the same same thickness same length same bend? if you filed the grounding strap/prong thinner would that change its harmonics?

I mean I buy this whole frequency/vibration thing lock stock and barrel becasue plugs are good for a 100,000 miles now in cars and my buddy has had the same plug in his 96 kx 250 for two years now . And my guess is that just a vibration or a high performance environment isn't the reasoning for these plugs as opposed to a particular frequency of the vibration.
I am sure if you change your plugs often enough you will never see a failure of the plug . I am also curious as too what Suzuki considers a decent life for a plug?How long did they run the same plug to get the failure? What kind of environment was it in ? I mean they could of ran an engine on a dyno for 200 hours and see what failed first . just curious

 

[David Trustrum]

A friend who used to work on a spares counter at a Suzi shop informed me of the need for RMs to run the expensive plug.

Mind you he had changed job. . . & they were a NGK distributor. . .

 

[biglou]

I know this is of little consequence, but the high-dollar plugs for the RMs do have the "GSP" (Genuine Suzuki Parts) logo on the box, regardless of where you buy them. I noticed that when the local shop I get most of my parts through (Husky dealer) ordered in a couple for me from P.U.

 

[SiCnTwIsTdYz]

i never knew that b4 thanks for the information dude i use a NGK BR9EG in my 2000 yz125 since the day i had it and they all seem to work great

 

[GeoffM24]

Since it is the 125 that has the vibration problem I assume it is safer to run the cheaper plugs in the 250?

 

[Nevada Sixx]

does an 03 rm 250 require a special sparkplug? or is br8es types ok?

 

[marcusgunby]

I think this problem is only seen in certain enviroments-i think its a certain rev range under a certain load where the plug will fail.However some riders may spend along time in this narrow window and so see alot of failures with std plugs.Average riders who change plugs often will probably never see a failure with a cheap plug.

 

[Luft]

The Suzuki manual for the 03 RM 125 calls for inspection every two hours and replacement every six hours. Believe it or not, I've just broken mine in and the bike starts 1 or 2 kicks with 30:1 and major spooge drooling out the back with the original plug and stock jetting. Based upon the response from NGK I will use the stock plug.

 

[Nevada Sixx]

marcus,, what range and rev load do you think does it? would a slow rider who doesnt slip his clutch have much to worry about?

 

[A-RustyDemon]

I've mentioned this before on Suzuki RM 125 plugs. I went to the dealer to purchase one of those $20+ NGK R6918B-8 plugs. I was told that the BR#ECS which is a double grounded plug is a recommend alliterative for it.. it's cost around $9 per. But all I really needed to use are standard BR#ES or BR#EG. the choice was mine. It's funny they claim is some harmonic issue now.. Seems I remember reading back when this high dollar plug thing came out. That Suzuki claimed the need was based on the fact of a higher output ignition and electrode tip melting was the reason behind it.. :think: Hmmm same plug different story.

 

[David Trustrum]

So what advantage is it for Suzuki if the sparkplug manufacturer is selling more expensive plugs? That is food for thought.

 

[marcusgunby]

Nevada Sixx this is totally a guees but i think its when you overrev you get the problems-i had it on my 01 CR125(they dont specify a expensive plug for it) and im a chronic overrever.Heres a pic of the piston(its the bottom 2nd from left)

 

[A-RustyDemon]

Originally posted by David Trustrum
So what advantage is it for Suzuki if the sparkplug manufacturer is selling more expensive plugs? That is food for thought.

Well who holds the the rights to the plug.. That's the real question is it NGK for making it or is it Suzuki who paid for it's development... and who really sets the price for this plug? So it could be said that Suzuki has a vested interest in that plug. :think: They do come in a Suzuki OEM box.

 

[Solid State]

Had the same experience with the stock plug for an '01 KX85. Spoke to NGK and got the same story about ground lead failure due to vibration. Wound up buying a bunch from the Kawasaki web site for much less than list price. Since NGK states that they actually test their plug designs and make modifications based on observed failures, it seems foolish to disregard their results. Guess I spend too much time and money on my motor to run the risk.

 

[bayou]

I have a 98 rm 250 and have paid as much as 35.00 for a plug.I have talk to ngk and suzuki factory rep and got the same answers as i have read here about electrode breaking off BRE series plugs. I have heard of this happening on rm's when you use the cheaper plugs. Personally i use the recommened plugs for the simple reason is 35.00 or what ever you are paying is cheap insurance,besides i get 2 years on one plug,racing and trail riding