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Thread: R1100RT and Autolite 3923's

  1. #1
    Registered User dieselyoda's Avatar
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    R1100RT and Autolite 3923's

    So, I can read, and some of the stuff I read is rather questionable. I read somewhere that my expensive NGK Iridium plugs weren't worth the money. I have also read about the dreaded "tailpipe explosion" that occurs with these bikes. My buddies riding tail gunner started calling themselves the Beemer Fart Smellers.

    Slammed a pair of Autolite 3923's into it a few days ago, the Fart Smellers couldn't complain today.

    In my opinion, started nicer, less hesitation and felt like an Airhead under my but.
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

  2. #2
    2UP RIDER snookers's Avatar
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    Same plugs that I use.....and they are cheaper than the OEM plugs as well.
    2000 R1100RT
    Niagara BMW Riders #298

    BMWMCO #45

  3. #3
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    +1 on the Autolite 3923's.

  4. #4
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    I use only Autolite 3923 in my '95 R1100R. About $3.00 for a 2 pack from Wal-Mart. Have never been disappointed.

    Mark

  5. #5
    Day Dreaming ... happy wanderer's Avatar
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    Not 100% sure but I think the use of Autolite 3923 plugs in the 1100 Oilhead was pioneered by Rob Lentini on his 1100RS. His articles on surging and performance form the basis of a lot of what is known about oilhead surging and how to alleviate it on various forums. Autolite plugs are a great and inexpensive alternative to BMW's recommended Bosch FR5DTC dual electrode plugs. The Bosch dealer sold plugs are at least $12 each up here last time I checked and really don't work very well at all compared to the single electrode alternative
    .
    I tried the standard 3923 and now use Autolite AP3923 which is the platinum tip version. They are noticeably better than the Bosch plugs performance wise and after over 20,000 miles show no appreciable wear. I think I paid about $4 bucks each for them.
    MJM - BeeCeeBeemers Motorcycle Club Vancouver B.C.
    '81 R80G/S, '82 R100RS, '00 R1100RT

  6. #6
    Benchwrenching PGlaves's Avatar
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    There is nothing particularly magic about the 3923 plugs. But they fit, they are readily available, they are inexpensive, and they are a single electrode plug.

    To understand why I mention a single electrode plug, do a search on the terms "indexing spark plugs". Here is an example - short but sweet:

    http://shop.advanceautoparts.com/web...Spark-Plugs___

    The earliest Oilhead 1100 bikes had triple electrode plugs. I don't know why BMW used them but do know that Cadillac used them to extend plug life to extend tune-up intervals to 100,000 miles.

    BMW later went to a dual electrode plug. Later they went to two whole spark plugs and the wretched stick-coil arrangement. Either 3, or 2 ground electrodes on a plug simply increases the odds that one of the electrodes is aligned with the incoming fuel charge and masking the spark. This hinders regular, complete combustion which is a primary cause of surging, less than optimal fuel mileage, carbon buildup, and probably a few other problems too.

    If you want to chase this as far as possible, use a single electrode plug and actually index the plug to orient the ground electrode away from the intake valves.
    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

  7. #7
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    Quote Originally Posted by queretaro View Post
    I use only Autolite 3923 in my '95 R1100R. About $3.00 for a 2 pack from Wal-Mart. Have never been disappointed.

    Mark
    Oh my god! Don't let some of the experts on this forum here know that you buy parts for your precious BMW at Walmart!!! They wouldn't even put that stuff in their lawn-mower....

  8. #8
    Nickname: Droid
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    I have well over 150,000 miles on my 94 RS running the Autolite 3923s. No issues. bike runs great, fuel mileage in the 45 to 48 range (Techlusion equipped).

  9. #9
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    3923's

    Have worked well in all my oilheads and absolutely more bang for the buck than the BMW/Bosch $12 alternative. Bikes seemed somewhat smoother as well

  10. #10
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    Quote Originally Posted by PGlaves View Post
    There is nothing particularly magic about the 3923 plugs. But they fit, they are readily available, they are inexpensive, and they are a single electrode plug.

    To understand why I mention a single electrode plug, do a search on the terms "indexing spark plugs". Here is an example - short but sweet:

    http://shop.advanceautoparts.com/web...Spark-Plugs___

    The earliest Oilhead 1100 bikes had triple electrode plugs. I don't know why BMW used them but do know that Cadillac used them to extend plug life to extend tune-up intervals to 100,000 miles.

    BMW later went to a dual electrode plug. Later they went to two whole spark plugs and the wretched stick-coil arrangement. Either 3, or 2 ground electrodes on a plug simply increases the odds that one of the electrodes is aligned with the incoming fuel charge and masking the spark. This hinders regular, complete combustion which is a primary cause of surging, less than optimal fuel mileage, carbon buildup, and probably a few other problems too.

    If you want to chase this as far as possible, use a single electrode plug and actually index the plug to orient the ground electrode away from the intake valves.
    I think this is why I like Bosch 4417 so much. 4 electrodes, and my surging is really minimized. On no alcohol fuels I often get 46 to 48 on spirited rides in the Ozarks.

    I do switch from side to side, every valve check, to equalize wear. Eventually the gasket will not seal anymore and I buy new plugs to get new gaskets. Anyone know where to get gaskets?

    Rod

  11. #11
    It is what it is. Bud's Avatar
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    Quote Originally Posted by EMSimon View Post

    Quote Originally Posted by queretaro View Post
    I use only Autolite 3923 in my '95 R1100R. About $3.00 for a 2 pack from Wal-Mart. Have never been disappointed.

    Mark
    Oh my god! Don't let some of the experts on this forum here know that you buy parts for your precious BMW at Walmart!!! They wouldn't even put that stuff in their lawn-mower....
    I don't think there is a problem with that Rod as long as you use BMW specs in setting the gaps.

    Now I wouldn't ever use a FRAM filter because everyone knows that it will ruin your engine in less than 3,000 miles. Haven't you seen the cut away pictures on the internet? I mean, come on now, cars are littered on the side of the road with blown engines because of cheap oil filters.

    I've use the Autolites with no problems.
    I used to post here, but now I don't.

  12. #12
    Jammess jammess's Avatar
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    Quote Originally Posted by queretaro View Post
    I use only Autolite 3923 in my '95 R1100R. About $3.00 for a 2 pack from Wal-Mart. Have never been disappointed.

    Mark
    Maybe a bit off topic so take me right out and shoot me just please don't use ammo from Wal-Mart. I wouldn't buy 3923 plugs at Wal-Mart or anything else at Wal-Mart for that matter. In fact, if Wal-Mart were giving away 3923 plugs I'd still go to NAPA to get them.
    Jammess

  13. #13
    Registered User dieselyoda's Avatar
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    Wasn't there a movie.......

    Quote Originally Posted by jammess View Post
    Maybe a bit off topic so take me right out and shoot me just please don't use ammo from Wal-Mart. I wouldn't buy 3923 plugs at Wal-Mart or anything else at Wal-Mart for that matter. In fact, if Wal-Mart were giving away 3923 plugs I'd still go to NAPA to get them.
    Isn't there a movie with Dustin Hoffman and Tom Cruise as brothers? Oh yeah, "Rain Man", I love that movie. OH, me bad, "K-Mart Sucks".
    1997 R1100RT (Restored Basket Case) , 1981 KZ 440 LTD (Restored Basket Case)
    1986 K75S(the beutch), 1993 K1100RS (blown engine), 1997 Chev Short Box (4x4 with an LT1)
    "You can easily judge the character of a man by how he treats those who can do nothing for him."

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