1981 900 SS fuse issue

[jsey]

All,
I've had a problem in past posts with lack of charging and have just completed re-wiring my stator in addition to double checking the wiring of my regulator. Having done all that, the reading on my multimeter while at idle reads about 11 amps and at 2000 rpm the amperage climbed to 14 amps, so I would say mission accomplished. One note, the generator light located at thhe dash stays on all of the time. One last problem. my fuse box has 4 locations but only 3 are used. One 25 amp and two 15 amp. The 25 amp fuse, where the hot lead from the battery hooks up with the lead going to the B+ on the regulator (same side of the fuse) gets so hot that it melts then fails. Any ideas Fuses are the european type that it origanally came with.

[abmartin]

I found this diagram for a 900 Replica which shows four fuses in the box but only three give amperage ratings. The fourth doesn't seem to be connected to anything so it might be a spare. In any case I've never felt the fuses on my bike to see how hot they get but it would seem that there may be a wrong or bad connection somewhere that is either passing too much current through the fuse or is creating too much resistance. I would go through the wiring and check all the connectors and grounds for tightness

If what you are measuring with your meter is volts not amps the numbers are correct.

I'm not a wiring expert though so will defer to someone with more experience in this area.

Bruce

[jsey]

Thanks. Did I say amps? Volts!!! I knew that

[wdietz186]

The fuses will get warm when in use. The Bosch style fuses have a smallish contact area at the fusebox tabs and corrosion or looseness will make them pretty hot. Make sure the tabs are secure and bend them inward so the fuses are snug also cleaning the inside of the dimples and the ends of the fuses to ensure full contact will keep them from being hot enough to melt things.Cleaning the connections at the other high load sources like the headlight,voltage regulator,and the switch gang plugs will reduce the tendency of the fuses to get overly warm.An added benifit is the lights may be a bit brighter too!

[Lumpy]

Unless your really pedantic about originality I`d get that standard fuse box and throw it over your left shoulder and fit one of those blade fuse holders. Cheap and cheerful and won`t let you down. I had a head light go out half way round a bend at night due to those fuse holders and now it`s the first mod I do to any bevel I`ve had.
One thing I would be a little wary of is the 11 volts at idle. Even when your alternator is not charging you should have 12 volts if your battery is in fine fettle. Is your battery in good nick? If your alt is struggling to pump enough juice in there it may cause heat. Try another battery if you have one laying around or hook a high rate discharge tester on the battery. Usually your local auto elec will be happy to test it out for you for little more than a thank you. I`ve seen batterys show 12 volts but have no amps to back it up. Although if memory serves yours is an S2 so you should pick up on that from the sound of the starter.
Apart from that I`d be incllined to agree with the lads. Resistance equals heat, be it on on earth connector or otherwise. Another sorce of heat can be short circuit, a hot wire making contact with the frame some place, although this will usually blow fuses but I always expect the unexpected with Italian electrickery. I`m no electrician but i have attended the Ducati and Moto Guzzi school of road side electric fault finding and my test light lives in my tool tray or jacket pocket.

[jsey]

Thanks all. Now I need to go to work

[jsey]

The wiring diagram that Bruce posted is identical to the wiring on my 1981 900 SS even though it is labled 900 Replica. Very helpfull. I cleaned all the connections and actually found a discrepancy on my bike, corrected it, and bingo end of problem. Thanks for all the help everybody!!!