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    What causes a melted harness?

    I got a 81 gs450 as trade for some parts and I'd like to get it running and back on the road and possibly do some track days too. Problem is I have no spark and after pulling the seat and tank I found some grounds that have melted. Im great with suspension, brake, and chassis mods but I suck with electrical problems. What would cause the grounds on the harness to melt and what is likely the fix? Is this the bad RR problem I keep reading about?

    #2
    the simple explanation is the current has to go somewhere. The ground provided paths of least resistance, essentially acting as a ghetto fuse. Pull the harness out and check all the connections. I prefer to beef up the ground wire layout on harnesses. Look through the manual on Basscliffs site and compare your harness to the manual's layout. A lot of times prior owners butcher wiring in efforts to customize
    It may be worth the effort to just find a known good replacement harness to get you running quicker.
    1984 GS550ES
    Rebuild in progress....

    1983 GS750ES
    4700 miles

    1978 GS1000E...Resto-mod to come

    Comment


      #3
      someone along the years may have hooked up jumper cables backwards or tried to start it with a running car...

      the R/R is probably fried

      Comment


        #4
        Dirty connections and bad grounds will cause melted wiring even with a perfect charging system. Clean every connection with a QUALITY contact cleaner de-oxidizer. I will suggest DeoxIT D, it's expensive (as far as contact cleaners go) but nothing else compares.

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          #5
          I would suspect the main ground wire was not very good along with the other ground connections and as barnbiketom said someone tried to jump start from a running car. I would even guess they used a cheap set of jumper cables. With that kind of voltage drop on a low voltage system you would easily be in "welding territory". The first thing I would do is to is replace the main ground with a heavier wire (I used 4 AWG), and replace all of the ground connectors. I have gotten in the habit of using stainless steel star washers on both sides of any ground connections so they they dig in and help maintain a good connection. Cleaning the connection surfaces with a wire brush and using a little dielectric grease helps keep corrosion and rust out. Go through the rest of the harness cleaning or replacing all connections as necessary. Then I would thoroughly check out the charging system. There is a lot of maintenance on an old bike to catch up on. A good source of connectors and the proper crimping tools is: http://www.vintageconnections.com/
          Last edited by OldVet66; 04-25-2013, 08:12 AM.
          '78 GS1000E, Dyna-S ignition, Dyna Green Coils, K&N pods, Delkevic SS 4-1 exhaust, Dynojet Stage 3 jet kit, Russell SS Brake Lines, Progressive suspension, Compu-Fire series Regulator 55402 and Advmonster cree LED headlight conversion.

          Comment


            #6
            one time i had a car in the shop that kept burning yes burning off the SHIFTER CABLE to the tranny hahaha.

            turns out the owner had an engine installed and they left off the main ground. when starting, the starter drew all it's current thru that shifter cable and eventually burned it off hahaha.

            look for the same thing. missing/bad grounds!! and
            HAVE FUN!!

            Comment


              #7




              Did they look like this along with a boiled out battery?

              As stated poor grounds are the cause (specifically the R/R ground). After a lot of analysis I figure that an old style R/R with only one SCR and a poor ground pickup from the R/R ground to the frame/battery will do this.

              On inspection I found it was current from ground ring lug to ground ring lug and not current through the harness that caused the insulation to burn off of the ground wire.

              Without a picture it is hard to say if this is the same situation. You should always clean up your grounds and fuse box. You need to clean corrosion. Naval Jelly is available at any automotive store and easily washes off with water.

              I would at least move up to a 6 wire R/R is no SERIES model is in the budget.

              After fixing my ground and no other changes the charging system was restored.
              Last edited by posplayr; 04-25-2013, 12:44 PM.

              Comment


                #8
                Originally posted by barnbiketom View Post
                one time i had a car in the shop that kept burning yes burning off the SHIFTER CABLE to the tranny hahaha.

                turns out the owner had an engine installed and they left off the main ground. when starting, the starter drew all it's current thru that shifter cable and eventually burned it off hahaha.

                look for the same thing. missing/bad grounds!! and
                HAVE FUN!!

                That is why I always recommend a single point grounding strategy.

                Last edited by posplayr; 04-25-2013, 12:47 PM.

                Comment


                  #9
                  My spare time has been spent building a shed lately so I havent done anything with the bike other then find some melted wires. A few of the grounds look exactly like the ones in the picture you posted posplayr.

                  So does anyone have a known good wiring harness for a gs450 that they could sell? I guess ill also have to do some searches for good rr replacements. Think the coils and stator are still ok or did they get fried during the melt down?

                  Comment


                    #10
                    Originally posted by Racing Geek View Post
                    My spare time has been spent building a shed lately so I havent done anything with the bike other then find some melted wires. A few of the grounds look exactly like the ones in the picture you posted posplayr.

                    So does anyone have a known good wiring harness for a gs450 that they could sell? I guess ill also have to do some searches for good rr replacements. Think the coils and stator are still ok or did they get fried during the melt down?
                    If it is like mine then you can just open up the harness wrap and replace the two burned ground wires and rewrap the harness. Solder that ground crimp joint to minimize corrosion.

                    Nothing else is probably bad except your poor boiled out battery.

                    Fix the grounds and go to a 6 wire R/R and you should be good.

                    Comment


                      #11
                      I never got a battery with the bike so I have no idea if it boiled over. I think ive got some black wire laying around somewhere.

                      Any good sources for the 6 wire rr that you can share?

                      Comment


                        #12
                        Originally posted by Racing Geek View Post
                        I never got a battery with the bike so I have no idea if it boiled over. I think ive got some black wire laying around somewhere.

                        Any good sources for the 6 wire rr that you can share?
                        There's one for sale in the parts section right now..

                        Comment


                          #13
                          Thanks for the heads up!

                          Comment


                            #14
                            Think a 06 (I think it's 06) r6 rr would work? I found one in my bin of wiring harnesses.

                            3 white
                            1 red
                            1 black wire
                            1 yellow cap

                            Do I treat the white wires like yellow wires?

                            Comment


                              #15
                              Technical Info posts that are deemed to be important or popular will be placed here for easier access. If you feel a post should be moved from the Technical Info forum to here then PM the Administrator with your request.


                              Correct, the whites are yamaha's equivalent to yellow. the post above will give more info than i can begin to try.

                              Also, look at Posplayers tutorial on proper grounding of the R/R to make the harness more robust if you haven't already
                              Last edited by Mista M; 05-17-2013, 04:17 AM. Reason: add info
                              1984 GS550ES
                              Rebuild in progress....

                              1983 GS750ES
                              4700 miles

                              1978 GS1000E...Resto-mod to come

                              Comment

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