79 wing main fuse melting

[mslade79]

Hi ,don't write into forums much so please bare with me thanks. I've owned my bike now for 18 years, dana ign. coils,wires randack spark caps ,rebuilt carbs , bike is an head turner . I,m having a fuse problem, everything works perfect, no shorts , no extra lites ect. but the main fuse holder gets hot over time and melts along with the 30 amp fuse, it doesn't happen right away. I've replaced the hold with a modern fuse holder a few years back. but noticed it had turned darker I didn't think much about it. till it burned up today on a ride. [the holder not the bike] SCARY. please anyone have any ideas.

[Sagebrush]

Well, you're obviously pulling right at 30 amps. If you were over 30 amps then the fuse would blow right away. I'm not sure what the plus minus tolerance is on fuses. I would suspect you have a corroded connection somewhere in the wire harness/electrical system causing resistance and extra current draw. The very first thing I would check would be the negative battery connection where it meets the frame. Its located under the left rear upper engine mount. Remove the long bolt, clean the frame where it connects to bright metal and clean the battery cable connection as well. If you can locate a star washer and put it between the frame and the battery cable it will enhance your connection by digging into the metal of both the frame and the cable connections when tightened.

[Whiskerfish]

Several years after I replaced the dogbone with a modern blade fuse it burned up on me. I had a trick getting home but upon further analysis afterward I am almost certain it was as Dean described. Many of those holders have a rubber cap and because of that people tend to forget about them and they build up dirt and corrosion in there. Pretty sure mine burned up for that very reason. I would replace it with new and then monitor it closely for a while but put it on a regular cycle to be cleaned and inspected.

[RB]

AND/or the negative cable itself corroded inside.

[mslade79]

thanks for input, never thought about the main frame neg. connection. I've check most connections and applied dye. grease to them after cleaning. the wiring on this bike is like new. bought it off my Uncle who bought in the factory box as a left over. ww2 vet . built planes form scratch. very professional. the bike was new when I got it . minus 1200 miles. I would hate to burn it up be cause stupidity. Is an upgrade to cbr solenoid and fuse recemenible ? I,m always looking to keep up with new tech. but to keep this bike looking orig. thanks Sagebrush and Whiskerfish.

[jdvorchak]

Very good advice above. Those guys know stuff. check for corrosion on the upstream side of that fuse. In other words toward the battery. Any resistance there would cause your fuse holder to run hot. Also on the down stream side from the regulator. Same thing corrosion will cause heat while it's charging. Depending on how you actually installed the new fuse holder it could be the old fuse holder has corrosion inside where you can't see it. If you just installed ring terminals on the fuse holder wires and screwed it into position where the old dogbone was you might consider cutting the dog bone holder out of the circuit and soldering the new fuse holder in it's place.

[BlueThunder]

+1. It may not be that you are pulling 30 Amps or anywhere near that. The corrosion in the connections or terminals has high resistance and causing a lot of heat. If you look at a resistor, it restricts electrical current. It does it by dissipating heat. That is what's happening in your main fuse. Replace the fuse holder and the connecting wires and you'll be good to go.

[77Gowing]

+1. It may not be that you are pulling 30 Amps or anywhere near that. The corrosion in the connections or terminals has high resistance and causing a lot of heat. If you look at a resistor, it restricts electrical current. It does it by dissipating heat. That is what's happening in your main fuse. Replace the fuse holder and the connecting wires and you'll be good to go.

Power = I^2*R, your R could be a high resistance path through a poor ground connection.

I Once had a Triumph Spitfire with Lucas Electrics, was my first car. Battery cables were always hot until I did a thorough cleaning of the battery terminals. At least it wasn't the prince of darkness's fault that time!

[mslade79]

WOW ! Thanks everybody . I know what I'll be looking for. I hate to see smoke. All's good. On the bounce guys.

[Rat]

Jeez .... DON'T let the smoke out ....

Gord (if it's already out, I have a jar (of smoke) that I bought on E Bay) Jones

[Toehead]

If you do, you can get more

http://www3.telus.net/bc_triumph_registry/smoke.htm

[Sidecar Bob]

+1. It may not be that you are pulling 30 Amps or anywhere near that. The corrosion in the connections or terminals has high resistance and causing a lot of heat. If you look at a resistor, it restricts electrical current. It does it by dissipating heat. That is what's happening in your main fuse. Replace the fuse holder and the connecting wires and you'll be good to go.

I agree. This is the same thing that causes problems with the (3 yellow wire) alternator connector.

If you have done the main fuse mod there is an easy test to see if this problem is coming: With the engine off and everything else on measure the voltage between the 2 screws where the fuse holder is connected. If you measure anything there, even 0.01V you have a bad connection.