resistor plug question
Close
    
    
Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 22
Like Tree3Likes

Thread: resistor plug question

  1. #1
    Senior Member YankeeRon's Avatar
    Join Date
    Oct 2013
    Location
    Connecticut
    Posts
    411

    resistor plug question

    After spending the better part of an hour looking for the answer, I'm resorting to just asking. I just recently did the brass rod conversion on my spark caps (well, aluminum rod in this case). What I understand is that a resistor is required somewhere in the system because it gives a hotter spark. By doing the brass/aluminum rod conversion, you then need to have resistor plugs. My question is other than performance, would running non-resistor plugs have any adverse effect on the engine?

    Ron


    Just north of Hartford, CT
    Current bikes
    1981 cx500 custom
    1984 Goldwing Aspencade
    Previous bikes
    1985 Goldwing Aspencade 1200
    1978 Suzuki gs450

  2. #2
    Senior Member reclinedrelic's Avatar
    Join Date
    Aug 2010
    Posts
    643
    NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking. NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance.
    Mike

    1981 GL500 (Jacob)
    1982 GL500I (Phil)
    1981 GL500 (Blackie) parts bike
    1983 GL650I (Big Red) parts bike
    198? CX500C (Adam) only a few parts left
    London, Ontario, Canada

  3. #3
    Super Moderator ramprat06's Avatar
    Join Date
    Aug 2010
    Location
    Vancouver, WA USA
    Posts
    9,611
    The 81c has no such electronic devices stock, it uses the CDI type ignition. The "noise" did have a minor effect on radios, but stock radios were not available except on the Interstate GL's.

    That said, it's not likely that any harm would come to any system of operation to run with no resistor at all. I would not bother fussing about it for the rather moot cost factor, and stay with a resistor in the mix somewhere.
    May the myriad of wheels in your head, keep the two wheels between your legs rubber side down.

    Age 61
    No more stable, no more ride for me.
    Forum Settings that everyone should make
    Photo posting tips!

    The WIKI link for all the good tech stuff. including free FSM's with addendums

    Larry's most excellent CX/GL Carb book link




  4. Remove Advertisements
    CX500Forum.com
    Advertisements
     

  5. #4
    Senior Member
    Join Date
    Apr 2011
    Location
    Lexington NC
    Posts
    19,196
    no resistor would actually change when the spark occurs (dwell)

    the reason melts my brain it has to do with how it charges to give the spark and a bunch of electrical engineering things

    if you need that info (lol) then either rayman or sidecar bob i am sure could give you the info

    i
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

  6. #5
    OCR
    OCR is offline
    Senior Member OCR's Avatar
    Join Date
    Sep 2010
    Location
    Groton NY
    Posts
    2,358
    Quote Originally Posted by reclinedrelic View Post
    NGK "R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking. NGK strongly recommends using resistor spark plugs in any vehicle that uses on-board computer systems to monitor or control engine performance.
    That also includes CDI, TI boxes.
    Past Master, Dryden Lodge #472
    Caroline Lodge # 681
    RAM Fidelity # 77





    '79CX500C

    http://cx500forum.com/mediawiki/inde...itle=Main_Page



    we are all given sh*t in life, but some of us learn to turn it into fertilizer and grow from it, and some us try to fling it on others like monkeys.

  7. #6
    Senior Member YankeeRon's Avatar
    Join Date
    Oct 2013
    Location
    Connecticut
    Posts
    411
    Thank you all - that makes sense. Resistor plugs ordered....

    Ron


    Just north of Hartford, CT
    Current bikes
    1981 cx500 custom
    1984 Goldwing Aspencade
    Previous bikes
    1985 Goldwing Aspencade 1200
    1978 Suzuki gs450

  8. #7
    Senior Member
    Join Date
    Dec 2011
    Posts
    353
    aviation spark plugs use resistors because it helps minimize the "burn time" the plug is firing and that reduces erosion for longer plug life. the additional resistor makes it so that the voltage has to be higher before it jumps the gap (there is a rise time no matter the source... picture the top of a sine wave). the spark cuts off quicker on the "down" side for the same reason (higher resistance) even though the gap is ionized. this is where the most benefit is gained because the fuel is already starting to burn, no need for more spark. realize that we're talking milliseconds here, so no.... not much effect on timing. Av plugs are shielded for noise, with shielded harness.

  9. #8
    Senior Member
    Join Date
    Apr 2011
    Location
    Lexington NC
    Posts
    19,196
    See what i mean????
    fsj likes this.
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

  10. #9
    Senior Member Peter in Cali's Avatar
    Join Date
    Jan 2016
    Location
    Santa Barbara
    Posts
    226
    You can think of the circuit as having coupled inductors (coils) with lower value inductors (wires) and stray capacitances, all driven by the CDI system in a very abrupt way. It's probably a lousy analogy, but think of a mechanical system with springs and weights and no damping, and a wacky latch in the system that will let things fly (spark) or suddenly grab it at one spot (no spark). You can get all sorts of crazy signals traveling back through the system, potentially causing damage.

    The resistor is analogous to a mechanical damper. It just seems like the right thing to do, and the experts keep arriving at 1000s of ohms as about the right resistance. Since I did the cap mod, I'm sticking with resistor plugs.
    Peter

    '79 CX500C, low miles

  11. #10
    Senior Member
    Join Date
    Apr 2011
    Location
    Lexington NC
    Posts
    19,196
    yup no headache answer

    they found it was better to have a new resistor with every plug change

    as opposed to having a resistor wire or cap that degraded and no one checked them

    or you would wind up changing plugs and wires or caps
    GET AN OIL FILTER ADAPTER

    Order The Quick Build Exhaust Pipes


    GET A QUICKSET VALVE TOOL


    Way to many bikes to maintain this list LOL !!

    email me at murray at murrayscarbs.com

Page 1 of 3 1 2 3 LastLast

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Similar Threads

  1. gl650 spark plug cap resistor removal
    By helithumper in forum Technical Help Forum
    Replies: 5
    Last Post: 03-20-2016, 04:06 PM
  2. Plugs, Wires, Coils, Caps.. and the Resistor question.
    By krharris in forum General Discussion
    Replies: 9
    Last Post: 08-14-2015, 09:08 AM
  3. resistor plug mod
    By crww in forum Technical Help Forum
    Replies: 0
    Last Post: 03-22-2014, 05:36 PM
  4. Removing the plug cap resistor
    By Bugsy in forum Technical Help Forum
    Replies: 6
    Last Post: 12-20-2011, 07:57 AM