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  • #1

    Quick electrical question

    The headlight relay on my 79 special has given up after all these years. The reserve lighting unit gave up last year so I did the RLU removal routine. In order to just ride I jumped two wires at the relay plug so now the headlight goes on and off with the key. I am thinking I might just leave it as is.

    Question is this....Will running the bike with the headlight jumped at the relay plug cause any electrical damage if left like that long term?

    I thought someone recently did a restoration of the headlight relay but I am getting no hits using the search function.

    Thanks
    Mike Giroir
    79 XS-1100 Special

    Once you un-can a can of worms, the only way to re-can them is with a bigger can.
    Tags: None
  • #2
    Mike, I've run both my XS's with no relay for years and everything was fine. One day I took the relays apart and found a wire came loose from it's solder joint. The hardest part was getting the relay open, but yes they should be able to be fixed.
    2H7 (79) owned since '89
    3H3 owned since '06

    "If it ain't broke, modify it"

    ☮

    Comment

    • #3
      I've ran with years with my headlight relay jumpered out on my G.
      Just make sure you use a decent gauge wire for that.
      All the headlight amps have to go thru that and it might get a little warm if it's too small a gauge.
      In my case, I think my diode may be bad in the harness.
      The same relay works fine in my SG, so my problem isn't the relay.
      Hi, my name is George & I'm a twisty addict!

      80G (Green paint(PO idea))
      The Green Monster
      K&N A/F, TC's fuse block, '81 oil cooler, TC's homemade 4-2 w/Mac Mufflers, Raptor 660 ACCT
      Got him in '04.
      bald tire & borrowing parts

      80SG (Black w/red emblems & calipers)
      Scarlet
      K&N A/F, TC's fuse block, WJ5, Shoei bags, Raptor 660 ACCT.
      Got her in '11
      Ready for the twisties!

      81H (previously CPMaynard's)
      Hugo
      Full Venturer, Indigo Blue with B/W painted tank.
      Cold weather ride

      Comment

      • #4
        The point of the relay is just to reduce load on the battery when starting the bike.
        Nathan
        KD9ARL

        μολὼν λαβέ

        1978 XS1100E
        K&N Filter
        #45 pilot Jet, #137.5 Main Jet
        OEM Exhaust
        ATK Fork Brace
        LED Dash lights
        Ammeter, Oil Pressure, Oil Temp, and Volt Meters
        Green Monster Coils
        SS Brake Lines
        Vision 550 Auto Tensioner

        In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

        Theodore Roosevelt

        Comment

        • #5
          one of these will handle just about any headlight you want to throw at it
          http://www.allelectronics.com/make-a...E-RELAY/1.html
          headlight Watts/Volt=Amps
          where are we going, and why are we in this hand basket?
          Iowa the Beautiful Land 1980 XS1100SG

          Comment

          • #6
            Yes, that relay the Jayel posted will work,

            BUT....it's not plug-and-play, it needs 12-14V DC on the coil to operate.

            The original Yamaha relay was designed to work on one phase of the alternator, which only supplies 7-8V AC on a good day.

            SO, I added another diode on another phase and ran them in parallel to the relay, and viola! any standard Bosch automotive relay can be used for the headlight relay.

            Oh, and I might add, if you want to retain the 'hold-in' feature so that the headlight remains on if the engine stalls, you need to backfeed the output pin to the + input pin of the relay coil.
            Last edited by DAVINCI; 04-18-2013, 08:06 AM.
            Former owner, but I have NO PARTS LEFT!

            Comment

            • #7
              Thanks guys, that's the kind of info I needed.
              Mike Giroir
              79 XS-1100 Special

              Once you un-can a can of worms, the only way to re-can them is with a bigger can.

              Comment

              • #8
                Originally posted by natemoen View Post
                The point of the relay is just to reduce load on the battery when starting the bike.
                There is very little current loss through that circuit when compared to the low reisitance of the starter. This is evidence by the dimness of the light when starting. Never had issues with the light ON while starting. I do have two of my 3 xs11s switched and a lighting relay used.
                Skids (Sid Hansen)

                Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                Comment

                • #9
                  Been fighting my headlight since small accident in october, e/thing works but the headlight. would love to know how to do this so I can ride. Sorry for jumping on ur post.
                  1980 xs1100g

                  Comment

                  • #10
                    Headlight Relay Bypass: Unplug unit and connect red/yel and blu/blk together at the harness plug. The unit is under the gas tank just in back of the ignition coils. It has a 4 wire plug.
                    2H7 (79) owned since '89
                    3H3 owned since '06

                    "If it ain't broke, modify it"

                    ☮

                    Comment

                    • #11
                      Originally posted by dschmitta View Post
                      Been fighting my headlight since small accident in october, e/thing works but the headlight. would love to know how to do this so I can ride. Sorry for jumping on ur post.
                      The headlight relay also controls the lights in the gauges, so if they are working, then the relay is working, if so, then your problem is closer to the headlight. Try checking the connections in the bucket.
                      Hi, my name is George & I'm a twisty addict!

                      80G (Green paint(PO idea))
                      The Green Monster
                      K&N A/F, TC's fuse block, '81 oil cooler, TC's homemade 4-2 w/Mac Mufflers, Raptor 660 ACCT
                      Got him in '04.
                      bald tire & borrowing parts

                      80SG (Black w/red emblems & calipers)
                      Scarlet
                      K&N A/F, TC's fuse block, WJ5, Shoei bags, Raptor 660 ACCT.
                      Got her in '11
                      Ready for the twisties!

                      81H (previously CPMaynard's)
                      Hugo
                      Full Venturer, Indigo Blue with B/W painted tank.
                      Cold weather ride

                      Comment

                      • #12
                        Originally posted by dschmitta View Post
                        Been fighting my headlight since small accident in october, e/thing works but the headlight. would love to know how to do this so I can ride. Sorry for jumping on ur post.
                        The aftermarket lighting relay works by connecting higher capacity wiring on the headlight circuit end, and lower capacity wiring on the switch side. The switch (ie from the handlebar) sends current through the relay, which really is just a solonoid that completes the circuit for the headlight side of the relay. I use a switch on the handlebar from a 1978 sx11 model E, but any switch besides a "momentary switch" will work.
                        Skids (Sid Hansen)

                        Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

                        Comment

                        • #13
                          Headlight inop

                          all gauges are functioning. When crashed, front fairing was smashed and L/S handlebar was bent right at hi/low switch. Do u think problem could be wiring from bucket back to main pass through harness? Been fighting this awhile. Got factory replacement fairing and h/light still inop, as matter of fact, previous owner had two small fog lights installed in fairing and they are also inop. T/signals work in fairing, just blink opposite of switch position(pushe switch L and R/S blinks and vice versa???) Any help greatly appreciated.
                          1980 xs1100g

                          Comment

                          • #14
                            Check the wiring connector at the fairing. Dark green is right turn, chocolate is left turn. These are the Yamaha colors. If I remember right, (my 80 is in a distant garage), the color codes of the wires in the fairing are different, but can be seen through the side openings.The wires can be switched in the connector to match up.
                            Bing Vetter, and I think his site has a wiring diagram for the fairings.
                            CZ

                            Comment

                            • #15
                              Will check. Thanks for info. Can't ride till get light and t/signals figured out. State inspection sticker is out and can't get sticker and get on road till lights are done. Thanks again
                              1980 xs1100g

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