Announcement

Collapse
No announcement yet.

The peril of a marginal main fuse.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    The peril of a marginal main fuse.

    Bike cut out today with no warning.
    Simple really, and I knew exactly what it was.
    The main fuse was 15A, and it had slowly sagged over the past couple of years, eventually breaking itself in the middle.
    Replaced it with a 25A and got going again.
    <makes note to ensure I have a selection of more fuses in the spares carried in the fairing pocket>

    ---- Dave
    79 GS850N - Might be a trike soon.
    80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
    79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
    92 XJ900F - Fairly Stock, for now.

    Only a dog knows why a motorcyclist sticks his head out of a car window

    #2
    You’ll want to put a 15A back in there then verify everything is still good (wiring, fuse block, etc)
    sigpic
    Cowboy Up or Quit. - Run Free Lou and Rest in Peace

    1981 GS550T - My First
    1981 GS550L - My Eldest Daughter's
    2007 GSF1250SA Bandit - My touring bike

    Sit tall in the saddle Hold your head up high
    Keep your eyes fixed where the trail meets the sky and live like you ain't afraid to die
    and don't be scared, just enjoy your ride - Chris Ledoux, "The Ride"

    Comment


      #3
      If you want to deal with it, there are small self resetting circuit breakers that plug into the same socket as your main fuse, they are taller. They are used in Lorry's in the US. When/if they blow they reset in 5 to 10 seconds normally. The up side is your are still protecting the circuit with the rated amperage, and you can start back up in a few seconds if it blows. It might not be worth dealing with, but it is nice to have options.
      1981 GS1100E
      1982 GS1100E



      "It is the mark of an educated mind to be able to entertain a thought without accepting it." Aristotle

      Comment


        #4
        ...Isn't the main fuse supposed to be 15A?
        #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
        #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
        #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
        #4: 1980 Moto Guzzi V65C – Something to chill

        Comment


          #5
          Originally posted by roeme View Post
          ...Isn't the main fuse supposed to be 15A?
          When you're on the side of the road with a non operating machine the rules don't necessarily apply. What's your other choice? Walk? Hitch hike to make sure you did it "perfect"? I'd put a screw in there if need be!
          1980 Yamaha XS1100G (Current bike)
          1982 GS450txz (former bike)
          LONG list of previous bikes not listed here.

          These aren't my words, I just arrange them

          Comment


            #6
            Hmm, put a bigger fuse and risk catching fire ...making a small problem worse? Or risk it! Most likely I'd put the right fuse in again for another try. And, only after certain considerations before a larger one or just tinfoil from a gum wrapper (set fire to the wrapper, tinfoil remains ):

            There are theoretically two types of fuses: slow blow and fast blow. That's the end of theory. I merely mention it as something to look for

            In the real world, I think fuses that get near their max might begin to age and weaken, but particularly

            Where new loads are added to a bike: aka heated vests extra lights. These would want a bigger MAIN fuse IF they are wired into an existing circuit (lights, accessory, etc.) BUT ,they properly should not be wired into an "existing circuit", because the Suzuki wire gauge is not overstrength.... so, while the new bigger fuse won't blow, the Suzuki wire is at risk...They should have their own independent and FUSED circuit to the battery, IMO.
            Last edited by Gorminrider; 05-12-2021, 02:19 PM.

            Comment


              #7
              Originally posted by Gorminrider View Post
              Where new loads are added to a bike: aka heated vests extra lights. These would want a bigger MAIN fuse IF they are wired into an existing circuit (lights, accessory, etc.) BUT ,they properly should not be wired into an "existing circuit", because the Suzuki wire gauge is not overstrength.... so, while the new bigger fuse won't blow, the Suzuki wire is at risk...They should have their own independent and FUSED circuit to the battery, IMO.
              That there is the fly in the ointment.
              I was thinking of what extras have been added, but near everything is independent and relayed.
              Except one thing... the fuel pump.
              Yes, it has an electric fuel pump that was added last year as a quick and dirty method to make sure fuel delivery to the SU wasn't restricted, while I was engaged in sorting out the final mixture.
              Totally forgot about it.
              Plus, the 15A fuse in the pic might not really have been 15A, who knows what it finally blew at, aided by vibration.
              ---- Dave
              79 GS850N - Might be a trike soon.
              80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
              79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
              92 XJ900F - Fairly Stock, for now.

              Only a dog knows why a motorcyclist sticks his head out of a car window

              Comment


                #8
                Well, you did the right thing getting home. But I just had to add all that, because this coffee makes me a pedantical!
                Nothing really wrong with the glass fuses except they are awfully hard to read the number on the little end and you do have to guess looking at the thickness!While these New Type Plastic Ones are colour coded! EZ!

                Comment


                  #9
                  Unless keeping the bike bone stock (and nothing wrong with that) replacing the fuse block with a modern one that takes modern, easy to find at every auto parts store in 2021 fuses is a top of the list mod in my book. The block I installed even has a few unused spaces where I can stick spares for just such an occasion.

                  Comment


                    #10
                    but the old panels fit perfectly and work ok too . I did a replacement box and it is taller, needed a "buss" made, and holes drilled to mount it.
                    I like it, but I can't say it's "better" unless it's necessary to replace the original.

                    Comment


                      #11
                      Originally posted by LAB3 View Post
                      When you're on the side of the road with a non operating machine the rules don't necessarily apply. What's your other choice? Walk? Hitch hike to make sure you did it "perfect"? I'd put a screw in there if need be!
                      Sure, sure, whatever gets one home. I would've done the same. I have enough experience with fuses to know that one needs to be cautious when the replacement fuse blows in short succession.
                      Fuses do get tired, and thankfully they go down in rating.

                      As for 25A vs. 15A melting the harness...I don't think so, if there really was a short-circuit, it would blow anyway, before any wire got the chance to heat up critically. And if the newly added loads exceeded the 15A,
                      it would've blown at the point of installation, not some (considerable) time later.
                      #1: 1979 GS 550 EC "Red" – Very first Bike / Overhaul thread        New here? ☛ Read the Top 10 Newbie mistakes thread
                      #2: 1978 GS 550 EC "Blue" – Can't make it a donor / "Rebuild" thread     Manuals (and much more): See Cliff's homepage here
                      #3: 2014 Moto Guzzi V7 II Racer – One needs a runner while wrenching
                      #4: 1980 Moto Guzzi V65C – Something to chill

                      Comment


                        #12
                        It's enough to melt and brown and, in one instance I have had to replace wires with insulation burned completely off on the long path to rear signals ... but I don't know the circumstance the original owner was engaged in.

                        But in the scale of actual flaming disaster, the tiny battery wouldn't last long enough and the stator only puts out 15amps or so max...225watts.

                        Comment

                        Working...
                        X