Results 1 to 9 of 9

Thread: '87 K100RS Intermittent Headlight - installing a relay

  1. #1
    No Time to Hate wavery's Avatar
    Join Date
    Dec 2011
    Location
    Glenside, PA
    Posts
    29

    '87 K100RS Intermittent Headlight - installing a relay

    When I turn my headlight on on my '87 K100RS, sometimes it works, sometimes it doesn't. When it doesn't, the high beam indicator lights up (with no actual high beam coming from the headlight).

    I understand headlight problems are common with these bikes, and reading through the forums the three things I see to do are: (1) check the ground; (2) clean the switch; and (3) install a relay a from Eastern Beaver. It sounds like No. 3 should be done regardless.

    So I'm a new to working on bikes in any form (or anything with a motor for that matter). While I aspire to be more, I would call myself a two-wrencher (out of five)...I can handle most of the routine maintenance. Is installing a relay relatively simple? From what I can tell, removing the tank is the most difficult task, but I don't see what 'installing the relay' actually entails once I access the wiring.

    I only recently bought this bike, after going far too long without one and I don't relish the thought of it sitting in pieces in my garage (nope, no winter hibernation for this bike). I have come to the conclusion that what I really need is a second bike so I'm not haunted by these weighty decisions (DIY or let a pro do it). Would someone please explain this to my wife?
    Last edited by 98lee; 12-30-2011 at 05:34 PM.
    Will
    87 K100RS

    Ride well my friends!

  2. #2
    Benchwrenching PGlaves's Avatar
    Join Date
    Oct 2003
    Location
    "Big Bend" TX
    Posts
    8,659
    Installing a relay is a good idea and you should plan to do it. BUT, that won't cure your problem until you get the lights in OEM configuration to work correctly, except by perchance lucky accident.

    You probably have a dirty starter creating a poor ground for the load shed relay. To correct this you need to remove and clean the starter. Tedious, but not difficult.

    Even with a relay setup the light won't work correctly if:

    a. the bulb isn't properly grounded
    b. the signal to the relay is turned off by the ungrounded load shed relay
    c. you have a bad high/low beam selector switch
    d. etc.

    Installing the relay kit is simple. Connect the ground wire, connect the fused lead to the battery, connect the relay coil signal wires per instructions (probably plug in to old headlight plug) and connect relay connector to the H4 light bulb.
    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

  3. #3
    Dum vivimus vivamus ted's Avatar
    Join Date
    Mar 2003
    Posts
    2,586
    I was going to throw out that you might want to check the switchgear wiring as well, the zip ties securing them to the frame rails and such can rub through the jacket and interior wiring over time causing all kinds of funkiness (technical term ). This sometimes happens with the wiring coming up the right frame rail where your right knee would be.
    Ted
    "A good stick is a good reason"
    1994 K75RT
    Moto Pages

  4. #4
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,383
    When Paul said the stater probably needs cleaning, he means the inside of the starter. The commutator gets covered in carbon brush dust and doesn't provide a good ground path.

    You MIGHT be able to confirm this, if you can get the lights to not work when the motor is not running, by putting the bike in 5th gear and pushing it backwards. If the lights come back on, the starter is probably the problem.



    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  5. #5
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    3,383
    Will,

    In the future, please include the year and model of the bike IN THE TITLE of the thread so that down the road others can more easily search for similar problems on similar bikes.


    Thanks.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  6. #6
    On the Road mattson4137's Avatar
    Join Date
    Mar 2008
    Location
    Oregon
    Posts
    17

    Relay kit

    Eastern Beaver makes a headlight relay kit for your bike. Simpler than creating some thing from scratch. http://easternbeaver.com/index.html

    Cheers,
    Merle

  7. #7
    No Time to Hate wavery's Avatar
    Join Date
    Dec 2011
    Location
    Glenside, PA
    Posts
    29
    Quote Originally Posted by 98lee View Post
    When Paul said the stater probably needs cleaning, he means the inside of the starter. The commutator gets covered in carbon brush dust and doesn't provide a good ground path.

    You MIGHT be able to confirm this, if you can get the lights to not work when the motor is not running, by putting the bike in 5th gear and pushing it backwards. If the lights come back on, the starter is probably the problem.
    Thanks all for the input.

    With the headlight out and the motor not running, I tried to get it into 5th gear but couldn't, so I started it up just to get it into 5th. The headlight came on as soon as I got it into 2nd gear. Is that indicative of a starter problem? Or anything else?

    Thanks again!
    Will
    87 K100RS

    Ride well my friends!

  8. #8
    No Time to Hate wavery's Avatar
    Join Date
    Dec 2011
    Location
    Glenside, PA
    Posts
    29
    Quote Originally Posted by 98lee View Post
    When Paul said the stater probably needs cleaning, he means the inside of the starter. The commutator gets covered in carbon brush dust and doesn't provide a good ground path.

    You MIGHT be able to confirm this, if you can get the lights to not work when the motor is not running, by putting the bike in 5th gear and pushing it backwards. If the lights come back on, the starter is probably the problem.
    I wasn't able to confirm a starter problem as Lee described, but from what I've read, it sounds like cleaning the starter is in order regardless. So far I've found these DIY write-ups on how to do it:

    http://www.ibmwr.org/ktech/starter-c...cleaning.shtml

    http://skylands.ibmwr.org/tom/tech/starter.html

    Any other suggestions or tips?

    Thanks all!
    Last edited by wavery; 01-20-2012 at 04:23 PM. Reason: Additional information found.
    Will
    87 K100RS

    Ride well my friends!

  9. #9
    Tom Mieczkowski mieczkow's Avatar
    Join Date
    Mar 2006
    Location
    St Petersburg, FL
    Posts
    284

    Add a Relay

    I can vouch for the value of a relay, and if you a going to replace the headlight switch this is a very good time to do it. The relay allows the current path to avoid relying on the relatively puny switch contacts to activate the light. One reason switches go bad is current overload from the start-up demand. The relay eliminates this as an issue. I added the Eastern Beaver relay set-up when I replaced my headlight switch unit and it also increased the luminosity of the light because of more efficient current transfer.
    Tom Mieczkowski
    1987 K75S

Tags for this Thread

Posting Permissions

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