The peril of a marginal main fuse.

[Grimly]

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>

 

[cowboyup3371]

You’ll want to put a 15A back in there then verify everything is still good (wiring, fuse block, etc)

 

[Guest]

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.

 

[roeme]

...Isn't the main fuse supposed to be 15A?

 

[LAB3]

...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!

 

[Gorminrider]

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.

 

[Grimly]

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.

 

[Gorminrider]

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!

 

[Guest]

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.

 

[Gorminrider]

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.

 

[roeme]

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.

 

[Gorminrider]

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.