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Thread: 1985 K100RS wiring question.

  1. #1
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    1985 K100RS wiring question.

    I am getting ready to install a pair of CREE 10W 800 lumen auxiliary driving lights on my front forks utilizing the front fender forward mounting location. I haven't decided how I am going to connect it electrically yet. I have an unused accessory harness which used the positive terminal on the alternator and is fused. If I wanted to use this harness would I need to fuse the lights because I would be running them off of the alternator? I believe I also have a heated handgrips 2-wire connector ( brown-green/black) under the tank that will work too. I would just have to snip the connector off and make up a pair of molex connectors.

    Thoughts?

    Thanks,
    Tom

  2. #2
    Registered User GTRider's Avatar
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    Quote Originally Posted by mcmlcccvrs View Post
    I am getting ready to install a pair of CREE 10W 800 lumen auxiliary driving lights on my front forks utilizing the front fender forward mounting location. I haven't decided how I am going to connect it electrically yet. I have an unused accessory harness which used the positive terminal on the alternator and is fused. If I wanted to use this harness would I need to fuse the lights because I would be running them off of the alternator? I believe I also have a heated handgrips 2-wire connector ( brown-green/black) under the tank that will work too. I would just have to snip the connector off and make up a pair of molex connectors.

    Thoughts?

    Thanks,
    Tom
    You really don’t want aux lights wired direct to alternator or to other circuits of unknown wire gauge and fusing. It’s a pretty simple task to run two-conductor automotive wire under the tank to the battery, where connections are easy and fusing easily accessible. You haven’t indicated how you plan to switch the lights, but if you want them auto-on/auto-off with the bike’s ignition an inexpensive relay triggered by the parking lamp in the headlight nacelle would be one option. You could also trigger the relay off the taillight feed, and mount the relay under the seat where it, too, is easily accessible.

    Best,
    DeVern
    DGerber
    1983 R80ST — 1984 R80 G/S-PD — 2004 K1200GT w/Hannigan S/C — 2010 K1300GT — 2018 R1200GS
    BMWMOA#52184, AMA#271542, IBA#138

  3. #3
    Registered User 6322's Avatar
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    I agree with DeVern. I added a Blue Sea box in my under seat storage (above the battery), to distribute power to additional accessories. I like having them on their own circuits, fused, and be able to turn them off at the ignition. 10W isn't much draw and may not need a relay. Also, I used a really simple mounting system under the headlight, attached to the fairing. I included a small piece of aluminum inside the fairing to add support for the mount.

    In theory, the lamps mounted on the forks, especially below the suspension, will take more road vibration which could lead to bulb failure. Mounted on the fairing they’re at least somewhat isolated. Good luck with your project.

    E7D21433-7A94-4F1A-859A-869C4E75ACCB.jpg
    Gary Phillips - #6322
    Wildland Firefighter, Retired, Riggins, ID
    Heartland Moto Locos BMW Riders
    '77 R100/7 Dirt Hack, '83 R80ST, '85 K100RS w/EML, '93 K1100LT, '00 R1100RS

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    Quote Originally Posted by GTRider View Post
    You really don’t want aux lights wired direct to alternator or to other circuits of unknown wire gauge and fusing. It’s a pretty simple task to run two-conductor automotive wire under the tank to the battery, where connections are easy and fusing easily accessible. You haven’t indicated how you plan to switch the lights, but if you want them auto-on/auto-off with the bike’s ignition an inexpensive relay triggered by the parking lamp in the headlight nacelle would be one option. You could also trigger the relay off the taillight feed, and mount the relay under the seat where it, too, is easily accessible.

    Best,
    DeVern
    +1 . ^^^ this. Consider a fuseblock connected to the battery: https://www.easternbeaver.com/Main/W...PC-8/pc-8.html . Then activate the aux lights with relays: https://www.easternbeaver.com/Main/W...s/h4_kits.html .
    Ray
    '74 R90/6. '75 R90S. '76 R90S. 2019 R1250RT
    Too many dirt bikes to list.

  5. #5
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    Hi guys,

    Thanks for the replies. If I=P/V then the current for each is 10W/12V=.83333A. I don't think that necessitates a relay. My plan is to activate the lights through an extra rocker switch as I want them independently switched. As mentioned before one idea was to source the 12V from the unused heated hand grip connector and I think that is the way I will go. I'll pull the tank this weekend and make sure that will work.

    I have no idea what the high/low power rating is of heated hand grips but I'll bet even the low is more than 10W.

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