'03 Suzuki RM125 Spark Plug

It is too bad that the search function sucks now because there was a great thread on this.

The reason given by NGK for the high price and "need" for the plug is that with the high vibration the tip of a standard plug can break off over time and damage the piston and cylinder.

I have a RM250 that is supposed to have a special plug too.

You can run a standard NGK resistor in there and just change it every once in a while and you should be fine but it is up to you.

I found'em here for $8 something a piece customcycle-atv.com I would buy like half a dozen at once by the time you add shipping and the prices for the plugs you could get what like two from the dealer. You'd save money in the long run it works out to be cheaper overall. I just got one for a 96 from the dealer it was $21 I have yet to find'em cheaper any where else so far.

I just run a standerd NGK in mine (02 Rm 250), that is what is in the manual. I hade the same discussion with a guy this weekend. I change mine about every 3-4 rides anyways.

Here is what NGK said

"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

We've
tested with Suzuki and
found the ES, EG, EV and EGV and determined these
spark plugs fail under
certain loads and conditions

Click to expand...

what about the EVX plugs??? My friend just had a BR9EYA fry the electrode and it did wonders on his piston and cylinder. I was thinkin buy the BR9EVX and replace it occassionally.....any thoughts

The br9evx is the plug tom morgan reccomened for my old 00cr 125 which the motor was built by him . For some reason I could notice a little difference between the evx and the eg the evx made my bike run differently not lights and day different but just enough for me to notice. I forget what he said to me at the world minis last year about the plugs but I know the evx is better than the eg and thats about it.

Well the RM 125 takes an #8 heat range plug, so the #9 is too cold. I tried for fun a BR8ES I had and the bike ran like crap with it in it. It wasn't as snappy and was laggy and then it just fouled out the plug. Switched to the special plug and it got back the little bit of loss in snap. The plugs are different looking especially the electrodes.

I think that the RM125 is actually a 9 heat range plug. I know my RM250 is a 8 range plug.

I recall reading something about the stock plugs heat range being somewhere between 8 and 9. Take that FWIW.

I run a BR8ES in my ' 02 RM125 and cannot detect a difference between it and stock. If you ride like a pro on GP type tracks, the vibrating ground electrode could become a problem if you don't change your plug often.

FWIW- I know of many people, including local pros, who run the BR plugs in RMs and have never heard of even one ground electrode failure. I'm not saying it doesn't happen, I'm just relaying my experience.

this spark plug issue is also a problem with the new kx125's

http://dirtrider.net/forums3/showthread.php?threadid=67116

when it goes wrong,, its no joke.

i am building a 02rm144 project bike up right now, i chatted with eric a bit, we discussed race gas etc. etc for this bike and then i asked him what spark plug to run......he chuckled and said "you better ask Marcus about that one!".

what plug will i run? dont know yet, but i think there are some denso plugs that have the better ground strap that are a bit cheaper.

i might add, there are several reasons people think this might happen, namely, 1. detonation and 2. some sort of wierd vibration harmonic humm. 3. some funky happenings with the ignition side of things (ties in with #1)

This is the pricing that I found through a wholesaler:

For prompt processing and order fulfillment, please enter all of
the following requested information.
Item 1
Description
Product Number Reference Number
Price (tax & shipping not included) Quantity Desire

#4492 NGK PLUG JAPAN R6918B8 $22.34ea

EACH! EACH!

As a comparison, look at what they want for a B8REVX, the platinum replacement for most bikes:
#1262 NGK PLUG JAPAN BR8EVX $6.40ea

This is a resounding reason for me to cite once again that Suzuki is pushing garbage product. I can buy about 4 plugs for a Honda or a Yamaha at that rate.

you can also buy 4 kawasaki plugs for that, but it will cost another 3 cylinder heads and piston kits. Or, you can buy a yam or honda, and with the money you save on plugs you could buy a new airbox sealing kit or new crank!:)

Originally posted by bclapham
you can also buy 4 kawasaki plugs for that, but it will cost another 3 cylinder heads and piston kits. Or, you can buy a yam or honda, and with the money you save on plugs you could buy a new airbox sealing kit or new crank!:)

Click to expand...

....

We can't win ha bclapham! Very good! :)

:thumb: Right on bclapham!  My KX didn't like the stock plug, the tiny little electrode was a magnet for water and fouling out (don't ask; enduros...)  I tryed a plug with the same heat range just a bigger electrode and that eliviated the problem all together.  My KX now is a submarine and enjoys long walks in deep mud holes.  On the RM's, the parts guy at our shop races them exclusively.  He changes the plug once a season, when he rebuilds the top-end.  He says the trick is with his bike is the brand of premix oil he uses.  I know its fully synthetic, something fancy, I forgot what the crap is called.   :uh:

Lissa, great point on the electrode size. Is that all that is different on the plugs? I noticed the same thing on my YZ 250. It is easy to foul th esmall electrode plugs, but I have never had the normal large plugs foul.

In hindsight, it looks like Marcus would not have had the plug failure, if he were running the RM plug. As he had stated, his detonation was not severe but any detonation can be a big deal and needs to be eliminated. When tuning on the edge for max HP it's easy to find some detonation, so the RM plug looks to be cheap insurance from what could be a major engine failure. :thumb:

So run the rm plug and no engine failure for the 03 kx125 ?? Im just wondering because I will be getting a 03kx125 soon , and if running that plug has what it takes to maintain reliability it will be done. Also havent decided on what type of oil ill be running, but it will be synthetic with 100 octane gas. Everyone can call me crazy but when I had my 00cr125 that bike never saw anything but 100 octane and higher never 91 or 92 etc. I had very good results from that bike and never blew it up not once as it was a full race bike as well, but I guess it matters how good you take care of it.

I ran the Suzuki plug in my 99 RM125. Even though they were expensive, with the proper jetting, I ran one plug for almost a year. I only changed it when it started showing wear. I carried an EVX plug as a spare just in case, but I never needed it.
Darrin

The root cause here appears to be detonation. So if your engine is having a problem with that, then RM plug could save you from a DNF. But the proper way is too eliminate the detonation. Using the proper fuel,jetting,timing, compression ratio and even the pipe choice is just some of the ways to tune it out. If your bike does not have a detonation problem or you know how to tune it out, then IMO the RM plug is not needed. For the worried or the less skilled in engine tuning, the RM plug may offer some insurance against an engine failure.

Steve what about the regular br9eg plug ? And i understand where your coming from about jetting and all the other stuff but it wouldnt hurt to use the rm plug for all the time use in the 03kx125 would it ? I just like the extra insurance and dont like stuff blowing up .

The RM plug will run just fine in the Kawie and won't hurt a thing :cool:

Good deal! thanks for your info ill add that plug to my list of things when i get my 03kx125.