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Thread: Alert: All Oilhead owners: Electrical issue

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    Lucky motorradmike's Avatar
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    Exclamation Alert: All Oilhead owners: Electrical issue

    While determining how to fuse my headlight wiring which I knew was unprotected, I discovered some other unprotected wiring. I've read about several harness meltdowns and one completely burned bike. See ON, Feb-2010. So this needs to be addressed.

    I believe this affects all Oilhead models, 850 - 1150, 1993 - 2004:
    Check your wiring diagram. If it's like the R1100RS, you'll see an unfused red line from Batt(+) to the load relief relay, and another to the ignition switch. These are critical because they flex whenever the bars are turned, and they sometimes have issues due to overtight zip ties.

    Mechanical:
    Two fuses are required. Here's how I mounted them in a vacant bay in the fuse box. I put in 10A for the pic, more on that later.


    Access:
    Access to the fusebox wiring is from below.
    Remove any tupperware in the way.
    Remove the rear wheel.
    Remove 4 philips screws from the top corners of the box.
    Remove 2 6mm Allen cap screws from the sides of the box.
    Remove 2 more Philips screws from below, they are near the top sides of the box which serves as the front of the rear wheel well.
    Pull the fusebox bottom down and out.
    Here's what it looks like with the lower fuse box part removed.


    Wiring:

    Here's the Batt(+) splice in the fusebox. The heavy wire comes from the battery, the other 6 are distribution.
    1/ Load relief fuse goes in the red wire to that relay.
    2/ Ignition fuse goes in the red wire you see here, heading up front to the ignition switch. The other 4 wires go to fuses already.


    First do no harm:
    Make nice splices. Solder the connections. No wires sticking out of the heatshrink. Neatness counts.


    Re-assembly:
    It's difficult to get the fuse box parts to mate properly. Do that first, taking care to get the 2 grommets seated correctly. Once the 4 top screws are in, the rest is easy.

    About fuses:
    It would be nice if a fuse could hold 100% of its rating indefinitely, but open instantly at 101%. Unfortunately they don't work that way. Fuses are blunt instruments. They work well protecting wire because they fail in the same manner, so can be a weak link. To size the fuses correctly, I intend to run the bike while monitoring current with an ammeter, then install a fuse with a rating of about 120% of the max. current I measure. I won't go below 5A or above 20A.
    You can read all about ATO and other automotive fuse Engineering here.

    I hope this helps save some bikes.
    Last edited by MotorradMike; 06-09-2012 at 04:46 PM. Reason: For accuracy, small error(correction in Red) pointed out by JLeather on ADVRider.com
    Mike Marr
    1978 Yamaha XS750 (Needs rings), 1996 BMW R1100RS, 2004 Honda CRF230F

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