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Thread: No Surge + Autolite 3923 plugs + wow!

  1. #1
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    No Surge + Autolite 3923 plugs + wow!

    Just went for a test ride. Can't believe the change from the Bosch FR6DDC plugs that were in the bike. Almost NO surge and almost imperceptible vibration now at 5k rpm!

  2. #2
    Registered User bluehole's Avatar
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    That is very encouraging. Is that change just from the plugs? I may give that a shot. I am not wrench savy, but I can do plugs..I think.

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    Lucky motorradmike's Avatar
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    Quote Originally Posted by bluehole View Post
    That is very encouraging. Is that change just from the plugs? I may give that a shot. I am not wrench savy, but I can do plugs..I think.
    Before you start, clean all the little stones out of the spark plug channel. Make sure the socket fits all the way down to the bottom.
    Some folks have had trouble when the socket gets jammed.
    Mike Marr
    1978 Yamaha XS750 (Needs rings), 1996 BMW R1100RS, 2004 Honda CRF230F

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    Lucky motorradmike's Avatar
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    Quote Originally Posted by mgordon View Post
    Just went for a test ride. Can't believe the change from the Bosch FR6DDC plugs that were in the bike. Almost NO surge and almost imperceptible vibration now at 5k rpm!
    So now you're a believer.
    Please provide an explanation if you can.
    To me, another believer, this fix is preposterous.
    Mike Marr
    1978 Yamaha XS750 (Needs rings), 1996 BMW R1100RS, 2004 Honda CRF230F

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    Quote Originally Posted by MotorradMike View Post
    So now you're a believer.
    Please provide an explanation if you can.
    To me, another believer, this fix is preposterous.
    All I can tell you is that I had noticeable surge, did obsessive TB sync, etc. Had very strong surging and fuel cut-off at low RPM. Changed plugs, rode the bike...and I'm a believer.

    Go figure, but remember Rob Lentini was the first one apparently to widely report the better performance. Fatter spark is my guess.

  6. #6
    Benchwrenching PGlaves's Avatar
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    Anybody who wonders how this can possibly be should do research on the term sparkplug indexing, and should then contemplate what the effect of two electrodes vs one electrode might be.

    Then go back and reread my Benchwrenching column from October and November, 2008.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Paul, are those ON issues accessible to anyone not a club member at the time? Online? I've come and gone a bit...

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    Benchwrenching PGlaves's Avatar
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    Quote Originally Posted by KEPPELJ View Post
    Paul, are those ON issues accessible to anyone not a club member at the time? Online? I've come and gone a bit...
    Unfortunately, no.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Registered User breyfogle's Avatar
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    Quote Originally Posted by mgordon View Post
    All I can tell you is that I had noticeable surge, did obsessive TB sync, etc. Had very strong surging and fuel cut-off at low RPM. Changed plugs, rode the bike...and I'm a believer.
    My 1100 never did surge, but when I bought it, it did stumble once and awhile at idle. It never actually stalled but it sure did not idle with confidence. Changing the stock Bosch plugs for 3923's completely cured the idle stumble. My 2 cent opinion is that the traditional axial-fire Autolites (and probably any single electrode plug) will ignite an ultra lean mixture better than radial-file multi electrode plugs like the Bosch.
    '89 K75S Original Owner
    '94 (Beta) R11RS, ( RIP 12-5-2010 courtesy of blind left turning cage driver ) ....

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    Breyfogle,

    Could you expand on why you think that ? I don't know, but I'd like to hear some ideas.
    Many moons ago I ran a auto parts business and the plug manufacturers touted the dual and multi electrode plugs as better than ice cream and free.........
    '03 R1150R, '03 F650GS, '97DR200SE,'78 Honda CT-90, '77Honda CT-90

  11. #11
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    Quote Originally Posted by PGlaves View Post
    Unfortunately, no.
    I agree with the "unfortunately" bit! I have raised this question before as to why the BoD's/editor don't make this tech stuff available in a reachable form. I have seen the answer but still have to say that given the level of tech interest in the membership, it is a shame we cannot go after this information/knowledge. Rant over...

  12. #12
    Certifiable User Mike_Philippens's Avatar
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    What was the condition/age of the old plug when you changed it? New?

    I had my bike serviced and when it came back it was fine, but I wanted to have the spark plugs everybody was talking about: the iridium. I swapped them against the brandspankingnew originals that the mechanic put in and went for a ride...absolutely no difference...

    So I wonder: is it not so that when you exchange old plugs for new ones, there will be an improvement, regardless if it's the wonderplug or just the original?
    -=- if you always see the road ahead of you, it's not worth the trip -=-

  13. #13
    Registered User breyfogle's Avatar
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    Quote Originally Posted by Acejones View Post
    Breyfogle,

    Could you expand on why you think that ? I don't know, but I'd like to hear some ideas.
    Many moons ago I ran a auto parts business and the plug manufacturers touted the dual and multi electrode plugs as better than ice cream and free.........
    Well, the thinking is like this (and ICBW!!): The intake charge drawn into the cylinder is very turbulent. Not all areas have the correct air to fuel ratio to ignite easily. In modern ultra lean burn engines, some of these areas are too lean to ignite while other areas are rich enough to ignite just fine. As the piston rises on the compression stroke, these areas of charge swirl around rather randomly. If the plug fires just when a lean area passes thru the spark gap a miss-fire occurs. With a traditional axial fire single electrode plug, the spark gap is very exposed to swirling flow from every direction except the small angle blocked by the side electrode. With multi electrode radial fire plugs, the spark gaps are tucked uo against the plug body and seem to be shielded from almost every direction. This increased shielding might decrease the chances any of the spark gaps "seeing" a combustable air to fuel ratio when the plug fires. Note also, just because a plug has multiple electrodes doesn't mean more than one spark is produced. On each cycle, only the one spark gap that sees the minimum resistance fires. The others do nothing except block the flow to the spark gap that does fire.

    :dunno
    '89 K75S Original Owner
    '94 (Beta) R11RS, ( RIP 12-5-2010 courtesy of blind left turning cage driver ) ....

  14. #14
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    i have you seen the price of membership

    lately? For the amount that we pay, they had better offer something that not anyone else can get.

    I seriously considered not renewing my membership this year when i found out how much my 5 year membership was.

    Rant off....




    Quote Originally Posted by kantuckid View Post
    I agree with the "unfortunately" bit! I have raised this question before as to why the BoD's/editor don't make this tech stuff available in a reachable form. I have seen the answer but still have to say that given the level of tech interest in the membership, it is a shame we cannot go after this information/knowledge. Rant over...
    Somers, NY

    Just enjoying the ride.......

  15. #15
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    Quote Originally Posted by breyfogle View Post
    Well, the thinking is like this (and ICBW!!): The intake charge drawn into the cylinder is very turbulent. Not all areas have the correct air to fuel ratio to ignite easily. In modern ultra lean burn engines, some of these areas are too lean to ignite while other areas are rich enough to ignite just fine. As the piston rises on the compression stroke, these areas of charge swirl around rather randomly. If the plug fires just when a lean area passes thru the spark gap a miss-fire occurs. With a traditional axial fire single electrode plug, the spark gap is very exposed to swirling flow from every direction except the small angle blocked by the side electrode. With multi electrode radial fire plugs, the spark gaps are tucked uo against the plug body and seem to be shielded from almost every direction. This increased shielding might decrease the chances any of the spark gaps "seeing" a combustable air to fuel ratio when the plug fires. Note also, just because a plug has multiple electrodes doesn't mean more than one spark is produced. On each cycle, only the one spark gap that sees the minimum resistance fires. The others do nothing except block the flow to the spark gap that does fire.

    Thanks for the follow-up. I get the physics involved, but I just don't know if it really matters. Of course, way,way back in college, a physics professor told me there are some things you just have to take on faith. I just shook my head and thanked him.
    '03 R1150R, '03 F650GS, '97DR200SE,'78 Honda CT-90, '77Honda CT-90

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