Spark Plug Thread

Discussion in 'Airheads' started by some_guy, Jan 23, 2013.

  1. some_guy

    some_guy Been here awhile

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    Replacing the plugs on a 95 R100RT that's new to me....well new enough to me that I'm just now replacing them. Anyway, Looks like I've been running Bosch W6DC plugs in it, installed who knows when but they look fine. I also have the 5K Ohm plug caps installed.

    The book calls for W7DC. I'm finding W7DC0 available online, don't know if there's a difference. Any wisdom out there? I'm not really partial to Bosch plugs, just figured I'd keep German plugs with my German bike and Japanese plugs with my Japanese car. I've seen some mention of the dual electrode plugs too, any real benefits? I read through a couple older threads, but didn't really find any of them leaning one way or another. Thanks for any info.
    #1
  2. supershaft

    supershaft because I can

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    I think someone said you can order W7DC's at NAPA? I get them at my local BMW dealership. Some people have been saying they are unavailable for years now and the whole time I have been getting them at my local dealership. I understand how some of these stories get started but I don't understand how they keep going and going?
    #2
  3. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    I've used NGK BP7ES or BP6ES in the /5 for nearly 40 years with no bad karma. Quality sparkplug with no angst about where-to-buy.

    --Bill
    #3
  4. Stagehand

    Stagehand Imperfectionist

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    the 5/6/7 is a heat range, of the spark produced I believe. I am running 7's in my R100. I think there are 5's or 6's in my R 60. Theoretically, you would run a hotter plug (one that produced a hotter spark) in the bigger cylinders, and you could run a colder one in the smaller.

    Dual electrode? Eh.

    I doubt the german vs japanese thing has any merit whatsoever. Both make perfectly acceptable quality plugs.

    This is abunch of other probably irrelevant info, but is a cool graphic:

    http://www.sl113.org/wiki/Electrical/SparkPlugs

    [​IMG]
    #4
  5. supershaft

    supershaft because I can

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    I think about all of them run better with Bocsh 7's in them versus colder plugs. I think NGK 6's are better in about all of them too versus the colder 7's.
    #5
  6. disston

    disston ShadeTreeExpert

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    I don't know what a DCO plug is. But W6DC and W7DC are available. Bob's BMW lists the W6DC for $6.20 and the W7DC for $6.88 each. The also carry NGK plugs but I don't know if the #s are a direct swap. They have a web site of course but the NGK plugs aren't on the web site. Call them. I think the phone works better for some reason at Bob's any way. Get a couple of things and try both brands of plugs. I'm using NGK but I forget what the number is.

    http://www.bobsbmw.com/
    #6
  7. Stagehand

    Stagehand Imperfectionist

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    makes sense with the shit for gas we get lately.
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  8. jackd

    jackd Long timer

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    +1 - readily available and inexpensive.
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  9. Airhead Wrangler

    Airhead Wrangler Long timer

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    Stage, since you note your heat range, but not the make of your plugs, it's worth adding that heat range numbers are not at all equivalent from one manufacturer to another:

    <table border="0" cellpadding="5" cellspacing="1" width="560"><tbody><tr><td class="middle" align="center" bgcolor="#f5f5f5">Heat Range</td></tr><tr><td align="center" bgcolor="#ffffff"> <table border="0" cellpadding="0" cellspacing="0" width="95%"><tbody><tr><td bgcolor="#999999"> <table border="0" cellpadding="3" cellspacing="1" width="100%"><tbody><tr><td class="text70" align="center" bgcolor="#dcdcdc">DENSO</td><td class="text70" align="center" bgcolor="#dcdcdc">NGK</td><td class="text70" align="center" bgcolor="#dcdcdc">CHAMPION</td><td class="text70" align="center" bgcolor="#dcdcdc">BOSCH</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">9</td><td class="text70" align="center" bgcolor="#ffffff">2</td><td class="text70" align="center" bgcolor="#ffffff">18</td><td class="text70" align="center" bgcolor="#ffffff">10</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">14</td><td class="text70" align="center" bgcolor="#ffffff">4</td><td class="text70" align="center" bgcolor="#ffffff">16,14</td><td class="text70" align="center" bgcolor="#ffffff">9</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">16</td><td class="text70" align="center" bgcolor="#ffffff">5</td><td class="text70" align="center" bgcolor="#ffffff">12,11</td><td class="text70" align="center" bgcolor="#ffffff">8</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">20</td><td class="text70" align="center" bgcolor="#ffffff">6</td><td class="text70" align="center" bgcolor="#ffffff">10,9</td><td class="text70" align="center" bgcolor="#ffffff">7,6</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">22</td><td class="text70" align="center" bgcolor="#ffffff">7</td><td class="text70" align="center" bgcolor="#ffffff">8,7</td><td class="text70" align="center" bgcolor="#ffffff">5</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">24</td><td class="text70" align="center" bgcolor="#ffffff">8</td><td class="text70" align="center" bgcolor="#ffffff">6,63,61</td><td class="text70" align="center" bgcolor="#ffffff">4</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">27</td><td class="text70" align="center" bgcolor="#ffffff">9</td><td class="text70" align="center" bgcolor="#ffffff">4,59</td><td class="text70" align="center" bgcolor="#ffffff">3</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">29</td><td class="text70" align="center" bgcolor="#ffffff">9.5</td><td class="text70" align="center" bgcolor="#ffffff">57</td><td class="text70" align="center" bgcolor="#ffffff"> </td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">31</td><td class="text70" align="center" bgcolor="#ffffff">10</td><td class="text70" align="center" bgcolor="#ffffff">55</td><td class="text70" align="center" bgcolor="#ffffff">2</td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">32</td><td class="text70" align="center" bgcolor="#ffffff">10.5</td><td class="text70" align="center" bgcolor="#ffffff">53</td><td class="text70" align="center" bgcolor="#ffffff"> </td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">34</td><td class="text70" align="center" bgcolor="#ffffff">11</td><td class="text70" align="center" bgcolor="#ffffff"> </td><td class="text70" align="center" bgcolor="#ffffff"> </td></tr><tr><td class="text70" align="center" bgcolor="#ffffff">35</td><td class="text70" align="center" bgcolor="#ffffff">11.5</td><td class="text70" align="center" bgcolor="#ffffff"> </td><td class="text70" align="center" bgcolor="#ffffff"> </td></tr></tbody></table> </td></tr></tbody></table> </td></tr></tbody></table>
    #9
  10. Stagehand

    Stagehand Imperfectionist

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    AW- I was thinking Bosch when I said, and thats a Bosch specific graphic, as well... the numbers dont jibe with NGK or anybody else I think. I've been using Bosch plugs in the BMW's, because they're easy to get from Max's when i order a bunch of crap. :D
    #10
  11. disston

    disston ShadeTreeExpert

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    I think most every body skipped the note about dual electrode plugs? Stagehand said "eh".

    I'll just add, stay away from gimmicks. Use name brand standard parts.
    #11
  12. some_guy

    some_guy Been here awhile

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    Yeah. Snowbum's site says not to use the dual ground electrode plugs too, but some were saying (in one of the older threads i was reading) they were running them with noted improved fuel economy.
    #12
  13. Airhead Wrangler

    Airhead Wrangler Long timer

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    I think you might be mistaking dual plugged heads for dual electrode plugs.
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  14. Airhead Wrangler

    Airhead Wrangler Long timer

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    oh, duh. missed the graphic
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  15. some_guy

    some_guy Been here awhile

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    #15
  16. Airhead Wrangler

    Airhead Wrangler Long timer

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    No, I know they exist, but dual plugging the heads is a common modification on airheads to allow higher compression ratios and it results in better gas mileage. So any mention of dual plugs on airheads and better gas mileage is probably referring to a dual plug head, not dual electrode plugs.
    #16
  17. supershaft

    supershaft because I can

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    Dual plugging is a common modification for airheads, oilheads, XR750's, top fuel dragsters, . . . all kinds of engines. Theoretically, it can get you better mileage. Some airhead riders get better mileage after dual plugging because they leaned their jets out afterwards. What a lot of those people don't realize is that they could have leaned out their jetting single plugged as well. Either way will often get you more power and better mileage all at the same time.

    Dual electrode plugs are basically aviation plugs. Your chances of a plug shorting out due to lead buildup are at least twice as small since if one electrode gets shorted the plug will fire through the other one until that one gets shorted. Better mileage? I doubt it but maybe they spark better long after they should be replaced? I don't know. The other electrode does shield the combustion mixture from the spark to some degree. I run single electrode plugs.
    #17
  18. disston

    disston ShadeTreeExpert

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    The problem with most rider assessments of benefit of modification is that they want it to work. If I had no other choice I'd use them but otherwise stay away. If you are really bored do your own tests. See if you can find any significant improvement in mileage or power. Understand tho we (the term "we" is used here very loosely) will tear test reports end for end. We are not generally a good audience for these things.

    It's true, No Free Lunch. :rofl
    #18
  19. supershaft

    supershaft because I can

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    I run NGK's in my bike now that it is dual plugged with 14mm and 12mm plugs just so I can have matching plugs. NGK's readily available? I have been to many a shop, even motorcycle shops, that do not have the NGK plug I am looking for. I don't think I have ever been to a BMW dealership that was out of Bosch WDC's. Even though you can't get them anymore! :lol3 I can't tell any difference between the two.
    #19
  20. motu

    motu Loose Pre Unit

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    So I'm safe to be using the 4 ground electrode then seeing as Snowbum doesn't mention them? No change in power or economy either way, the only advantage is longer life and they cover 2 heat ranges.
    #20