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Thread: Spark Plug Q

  1. #1
    Frieden mit uns allen drummer's Avatar
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    Spark Plug Q

    What is the general feeling about switching from Bosch plugs to say NGK? What about going from standard to iridium? Just curious.
    05 R1200RT
    Duragloss, Sidi, Russell, Olympia, Arai
    Sonor Signature Series (no longer made thanks to AMF buying Sonor)
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  2. #2
    Registered User ANDYVH's Avatar
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    Many Oilhead riders use plugs other than the expensive Bosch multi-tip plugs.
    I use the Autolite 3924 plugs, $1.99 each, and the bike runs great. In fact, many Oilhead riders replace the standard Bosch plugs with conventional plugs (Champion, NGK, Autolite) and report a better running bike.
    Get trained! The best "performance" upgrade you can get is YOU. Visit msf-usa.org for training info.

  3. #3
    Frieden mit uns allen drummer's Avatar
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    Thanks Andy -
    Do you have any concerns about heat with other types of plugs? Also, with the extended wrench to change out the plugs, how do you verify the torque or is that something you just don't worry about?
    05 R1200RT
    Duragloss, Sidi, Russell, Olympia, Arai
    Sonor Signature Series (no longer made thanks to AMF buying Sonor)
    These are a few of my favorite things ...

  4. #4
    Registered User breyfogle's Avatar
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    Quote Originally Posted by drummer View Post
    What is the general feeling about switching from Bosch plugs to say NGK? What about going from standard to iridium? Just curious.
    I have no particular problem with Bosch branded plugs but I do very much dislike any plug maker's multi-electrode, radial fire, style plugs. IMHO, single electrode, axial fire, plugs expose more fuel/air mixture to more spark. In oilheads that are setup close to the lean burn limit, the latter seem to work better than the former. Just my $0.02.
    '89 K75S Original Owner
    '94 (Beta) R11RS, ( RIP 12-5-2010 courtesy of blind left turning cage driver ) ....

  5. #5
    Rally Rat HFD190's Avatar
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    Why would you want to try something other than the Bosch plugs? In the grand scheme of things the cost difference isn‘«÷t significant.

  6. #6
    bob1100rtc
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    I use Champion RC9YC in my R1100RT. Work great

  7. #7
    rayadams
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    what about the 1150 two spark??? does anyone know alternate part numbers for those odd ball plugs? one plug is Bosch & the other is NGK.

  8. #8
    Registered User ANDYVH's Avatar
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    As to "heat" relative to plugs that can be misleading discussion. The heat generated in the combustion chamber is not much a factor of the plug itself. The amount of air/fuel mixture, and the compression ratio, are what determine how much heat an engine will develop per power stroke.

    Now, plugs come in different "heat ranges", but that only refers to the amount of heat the plug retains in the central porcelin core of the plug itself. It has nothing to do with how "hot" or how "cold" an engine runs. People mistakenly refer to plugs as being "hotter" or "colder" thinking it affects the running temperature of the engine when actually it does not.

    A "hot" plug simply means the plug construction retains more heat from the combustion process in the plug body itself. This tends to have a self-cleaning effect on plugs used in engines where a "colder" plug tends to get dirty and foul, perhaps due to excessive city driving.

    A "cold" plug means the plug retains less heat in the porcelin core of the plug. Now, if missapplied to an engine, a cold plug can cause soot buildup on the plug which can cause the plug to "short-circuit" a spark path other than at the plug tip. That action in an engine can cause fuel mileage loss and a poor running engine.
    Get trained! The best "performance" upgrade you can get is YOU. Visit msf-usa.org for training info.

  9. #9
    Quote Originally Posted by Andy VH View Post
    I use the Autolite 3924 plugs, $1.99 each, and the bike runs great.
    Did you mean 3923? I've never heard of anyone using a 3924.

  10. #10
    Frieden mit uns allen drummer's Avatar
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    Andy -
    Thanks for the information. You are helping me to understand and for that I really appreciate your input. One hears so much "stuff" about plugs that it becomes a topic surrounded in myths - you have helped me cut through the junk.
    05 R1200RT
    Duragloss, Sidi, Russell, Olympia, Arai
    Sonor Signature Series (no longer made thanks to AMF buying Sonor)
    These are a few of my favorite things ...

  11. #11
    feds27
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    Thumbs up Converted Bosch 2ndary to NGK

    I have a dual spark R1100S. I recently changed from the BMW recommended NGK primary and Bosch secondary plugs both with dual grounds to the same NGK primary but an NGK secondary with single ground for the secondary plug. I noticed a huge improvement right away. It could be my previous set of plugs needed a changing anyway and any new plugs would have given me an improvement. All I know is that the new setup is much smoother and better response on throttle. I also did a TB sync after the plug change. I posted more info on the pelican parts r11s forum. The site is undergoing an upgrade so I couldn't past a link, sorry.

  12. #12
    Frieden mit uns allen drummer's Avatar
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    Has anyone spent the money on the iridium plugs? I am wondering how they have turned out for others before I spend $16.95 a plug.
    05 R1200RT
    Duragloss, Sidi, Russell, Olympia, Arai
    Sonor Signature Series (no longer made thanks to AMF buying Sonor)
    These are a few of my favorite things ...

  13. #13
    Registered User kwazimoto's Avatar
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    I`ve been using the Autolite 3923s for years (75k)R1100RT,NO problems Read Rob Lentini`s article at the IBMWR tech section-he goes into depth.
    Knees in da breeze is my only disease

  14. #14
    Registered User ANDYVH's Avatar
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    Yeah, I am running the Autolite 3924, when a lot of people run the 3923. The 3924 is simply a slightly "hotter" plug than the 3923. Is has the same threads, just a slightly longer center porcelin than the 3923. Since I have no contact issues with the piston the reach is not an issue and my plugs are the proper color, and I get good mileage, and no surging.
    Get trained! The best "performance" upgrade you can get is YOU. Visit msf-usa.org for training info.

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