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Two-stroke gurus?

Discussion in 'The Garage' started by Ghoti, Jun 28, 2007.

  1. Ghoti

    Ghoti Sooper Brane Supporter

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    What is the difference between a G rated spark plug, (it has the small electrode) and the "normal" size eletrode. For reference I'm comparing NGK BR9EG and a BR9ES.
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  2. dancy

    dancy Undescended Testicle

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    I think G=gold and S=steel?
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  3. mudgepondexpress

    mudgepondexpress Long timer

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    N3G plug you are talking? In that case Gold (palidium sp?) tip. The used to have a C for copper tip also.

    I hate Champions! In cars I run autolites or motorcrafts, in bikes its NKG's only.

    The lawnmower gets a fresh Champion once every 7 years or so.

    Kenny
    #3
  4. Ghoti

    Ghoti Sooper Brane Supporter

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    I found it, G = nickel alloy center electrode, S = 2.5 mm center electrode.
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  5. Duck_Pilot

    Duck_Pilot Retired Roadracer

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    The two plugs will interchange, but one may serve you much better than the other depending on your use. The BR9ES is a standard-type plug, and will perform well under a variety of conditions.

    The BR9EG is a gold paladium-type racing plug, and may serve you better in hard riding - provided your jetting and everything else is spot-on. If this is bring used in a playbike or street machine, it'd be a waste of money.

    I used the standard plugs to tune my 2-stroke Suzuki roadrace bikes at the track, then change to the racing plugs before the first event. Sometimes I felt a difference, but it may have been wishful thinking, too. *grin*

    Viva Il Duckie!!
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  6. Scottysix9

    Scottysix9 Shhh...

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    Fancy sparkplugs WILL NOT give you more power. Remember SplitFires? Remember the lawsuit the State of Texas brought against them for making false claims?

    A cranky old man that built racing engines for two-stroke watercraft always told me, "buy cheap plugs and expensive beer."

    Stick with the ES's at two bucks each, buy an extra in case you foul it and buy some Heineken.
    #6
  7. JTT

    JTT Long timer

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    Ditto...only stick with Guiness :1drink
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  8. potatoho

    potatoho Cheese and Rice!

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    I love fitting fancy new spark plugs into the two stroke. There are subtle performance differences between a lot of them, and also different starting and anti-fouling characteristics, as well as slight combustion timing differences.

    It takes so little change to affect the running of a two stroke motor. You just have to experiment a bit to find the design most compatible with your motor. It's not always about power increase. For example, I have a couple of Brisk surface gap plugs that sometimes I run because I like the somewhat smoother overrun. They produce a very long 4mm spark which makes a unique feel to the motor. Unfortunately they foul like crazy on the two stroke if you aren't careful.
    #8
  9. ixion

    ixion Adventurer

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    I agree with that (assuming cheap doesn't mean some unheard of brand from China).

    Over the years I've tried all sorts of things around two smoker spark plugs. Cheap ones, fancy platinum ones, surface discharge ones, all sorts.

    At the end of it I'm unconvinced that expensive plugs perfrom significantly better than "run of the auto shop" ones.

    Maybe if you've got a temperamental sulky two stroke that nothing seems to sort ( as if there was any other sort !) , then try a different spark plug type. Otherwise, just stay with the ordinary stuff.

    And mines a Speight's thanks. If it ain't Speight's it ain't beer.
    #9
  10. reality checker

    reality checker FWG

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    I think the point of using the more expensive plug is not to give a better quality spark or light the charge off better, it is to resist fouling. If you never foul a plug, you do not need to use an expensive plug.

    I believe that the smaller electrode with the more exotic materials may be designed to hold together at a higher temp that the reduced mass of the smaller electrode may be exposed to.

    There are not many high performance 2 stroke machines left, but snowmobiles have hot two strokes that may weigh 75 lbs and can be tuned to 150HP+. The fuel consumption is about 10MPG depending on how the sled is ridden. The engine pumps fuel thru and burns what it can. Sleds are prone to fouling plugs and the rare metal small electrodes can reduce fouling. According to manufacturers recomendations in owners manuals, some sleds should be rejetted about every 10 to 20°f temp change.

    If you run a plug that fouls less, you may be able to allow richer mix as the OAT temp goes up without fouling. You will lose some performance though as the mix gets richer.

    Some sled tuners get real fussy about indexing plugs, they make sure the gap in the plug is exposed to the incoming fuel charge. Opinions vary on where the gap should be. I gave seen shims installed under plugs to insure the electrode is in the correct position.
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  11. JTT

    JTT Long timer

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    I may be wrong (have been lots of times before), but I don't buy that arguement. Fouling is normally not a function of the resistance of the plug (unless you have a weak ignition) and lower resistance is the real advantage of the "high end" plugs. The resistance to fouling comes from the tip temperature of the plug and that is determined by the heat range. A B8ES should therefore have the same tip temp as a B8EV.

    Fouling is best controlled with proper jetting and plug heat range. Most folks in the dirtbike world (aside from real fast guys) can benefit greatly from simply running one heat range hotter than stock (lower number on NGK).
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  12. reality checker

    reality checker FWG

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    <TABLE class=MsoNormalTable style="WIDTH: 100%; mso-cellspacing: 0in; mso-padding-alt: 7.5pt 7.5pt 7.5pt 7.5pt" cellSpacing=0 cellPadding=0 width="100%" border=0><TBODY><TR style="mso-yfti-irow: 0; mso-yfti-firstrow: yes; mso-yfti-lastrow: yes"><TD style="BORDER-RIGHT: #d4d0c8; PADDING-RIGHT: 7.5pt; BORDER-TOP: #d4d0c8; PADDING-LEFT: 7.5pt; PADDING-BOTTOM: 7.5pt; BORDER-LEFT: #d4d0c8; PADDING-TOP: 7.5pt; BORDER-BOTTOM: #d4d0c8; BACKGROUND-COLOR: transparent" vAlign=top>JTT,
    No need for you to buy the argument. The heat to reduce fouling is not the heat range of the plug, that is another topic, it is the heat at the electrode tip,the heat that is retained between ignition events.

    Quenching

    To understand quenching and how it is reduced it is first necessary to review the basic purpose of the spark plug is to ignite the air fuel mixture in the combustion chamber. To do this your vehicle ignition system generates tens of thousands of volts to jump the gap between the center and ground electrodes. However it is good to know that it is not the actual electricity that ignites the air fuel mixture, it is the heat energy generated by that electricity or spark. Therefore when you are creating the spark you want as much of the heat from that spark to be used to ignite the air fuel mixture and not have the heat from that spark be re-absorbed by the center and ground electrodes. Thus NGK makes a variety of designs(cut back ground electrodes, V-groove center electrodes, fine wire center and ground electrodes) all resist quenching by reducing the contact(surface) area between the electrodes and the flame nucleus.


    <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p>Here is a link to information about plugs, not two stroke specific, you may have to use logic and experience. </o:p>
    <o:p>http://www.ngk.com/sparkplug411.asp?kw=Ultra%2Dfine&mfid=1</o:p>
    <o:p></o:p>
    <o:p>I can say that in the thousands and thousands of miles I have put on two strokes, fine electrode plugs foul less often. I believe that a BR8EV will foul less often than a BR8ES. From my experience, I believe it is because the electrode stays hotter.</o:p>
    <o:p>To have perfect mixtures, rejetting should be done whenever Outside Air Temps or altitude change very much, the perfect jetting is hard to maintain, it seems to be a compromise between lean enough for performance and rich enough for durability. </o:p>


    </TD></TR></TBODY></TABLE>
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  13. JTT

    JTT Long timer

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    I can see the electrode getting hot faster because of it's smaller surface area, but in turn it will also cool faster. Like heating a bit of steel rod vs. a small guage wire. Perhaps this faster heating/cooling cycle helps fouling, but I've not seen significant differences in my experience with them.

    Heat range does effect fouling though as the colder (higher number) plug disappates more heat. I can tell you that if you have a spot on jetted 125MXer, that the spode riding it will benefit from a heat range higher than the Pro and it will be clearly visable on the plug insulator, as the hotter plug burns off more effectively....but could overheat under severe loads applied by a Pro rider.
    #13