Fuse size to use?

[Jim]

I'm thinking to put an inline fuse from my battery to the battery wire on my 1946 Indian. What size FUSE should I put inline? Only running a headlight, fender light, Speedo light, and tail light. Nothing "extra".

[joe fxs fxr]

You should size the fuse to gauge of the wires behind it. 15A is probably best, but I don't know what you are running.

[PaulCDF]

On my 46 converted to 12volt I am running 20Amp.

[Jim]

Thanks guys! I should've mentioned mine is still a 6V. First, I'll see what gauge the wires are... but if I can't figure that out, I think I'll start with the 15 and if it blows (for whatever reason) I'll go up to a 20.

[motor-officer]

I have run a 10 amp on mine for years with no problem.

[Jim]

I have run a 10 amp on mine for years with no problem.

Nice! Thanks for the info! I found a wire that's bare just at the handlebar hole. Which led me to think I BETTER put a fuse on it!

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[ChiefTwoKicks]

There you go Jim... if you blow a fuse, any fuse... its probably a wire thats gone bare or in some other way compromised, (pinched,or broken, and touching the metal frame or other component.
a higher rated fuse usually means the wire that is faulty has more heat and time to mess things up in a much fashion... like burning up the whole harness !!

Good on you for finding the problem, before its too late !!


Roger

[dukekleman]

Typically I run a 20 amp fuse.
If you have a Amp clamp or a DVOM you can measure your amp draw at the battery with all things applied (Headlight High beam, speedo/dash bash, running tail light w/brake light illuminated.
This is quick and easier than calculating the math on all items individually. Very accurate in the end.

[otis71]

I put inline fuses in all my Harley big twins. I use 30 amp fuses. Least little touch working on it (sometimes forget to remove fuse before doing something) and it blows instantly. I think the bigger fuse might be a little more vibration resistant. Vintage triumph service manuals call for 30 amp fuses and they only charge around 4 amps.

[Jim]

I put inline fuses in all my Harley big twins. I use 30 amp fuses. Least little touch working on it (sometimes forget to remove fuse before doing something) and it blows instantly. I think the bigger fuse might be a little more vibration resistant. Vintage triumph service manuals call for 30 amp fuses and they only charge around 4 amps.

Good info about the Vintage Triumph using a 30A! Thanks I just looked at the wire diagram for my 1965 Honda CB160 and that shows a 15A fuse.

[otis71]

I have a Yamaha RD350. If memory serves its 20amp.