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Thread: The peril of a marginal main fuse.

  1. #1
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    Default 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. #2
    cowboyup3371's Avatar
    cowboyup3371 is offline Forum LongTimer Past Site Supporter
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    You’ll want to put a 15A back in there then verify everything is still good (wiring, fuse block, etc)

    Cowboy Up or Quit. - Run Free Lou and Rest in Peace

    1981 GS550T - My First
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  3. #3
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    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



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  4. #4
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    ...Isn't the main fuse supposed to be 15A?
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  5. #5
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    Quote 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!
    1983 Naked Goldwing Interstate GL1100

    1982 GS450txz (former bike)

    "It is difficult to get a man to understand something when his salary depends upon his not understanding it" ~ Upton Sinclair

  6. #6
    Gorminrider is offline Forum Sage Past Site Supporter
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    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 at 02:19 PM.

  7. #7
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    Quote 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

  8. #8
    Gorminrider is offline Forum Sage Past Site Supporter
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    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!

  9. #9
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    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.

  10. #10
    Gorminrider is offline Forum Sage Past Site Supporter
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    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.

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