All of my bikes except the one Im currently building are wired up the one fuse way. The one fuse way makes the initial job easy and tracking problems difficult.
Also, there are items you might want to run (GPS, self cancel turn module etc) that need more protection than the single 20 amp main fuse offers.
I was able to purchase one of my Vincents because it was wired one fuse. Bit of a long story, the bike was brought over to Vancouver from the UK in 1980 in very rough shape. The purchaser, Leo was pretty enthusiastic about owning a Vincent and tried to get some fun miles on the bike, but everything was wrong with it.
In 1984 he took the bike to one of the best Vincent rebuilders on the planet, John Mcdougall. leo told John to tear it down to the crankpin and replace everything and anything needed. John pretty much does that anyway, but on this bike about all they kept were cases, frame members and the heads, which got everything renewed. John wired the bike up the one fuse way.
They put about 15k of parts and 10 k of labour into the bike. Once it was fired up it ran great except the fuse would burn out intermittently and also the new battery had a tendency to disharge rapidly, which left Leo stranded on several occasions.
John M looked it over and suggested the problem was in the Lucas generator, one of the very few original parts not replaced. He told Leo to buy one of his "Mcdougallators"which are a Kubota tractor alternator fitted into a housing and drive system made by John. They work very well and cost $1200. Leo was getting sick of spending on the bike so he did not purchase the Mcdougallator but took the bike to AutoMarine Electric Repair to see if they could figure out the problem. They tested the generator and found it was working properly and could not find any shorts in the electrical system anywhere.
Leo continued trying to ride the bike, but every other outing the fuse would pop, the battery would drain or sometimes both would occur. He and the bike often came home in the back of a pickup truck. After awhile he just stopped riding it.
About four years ago he sold it to me, having put just 550 miles on it in twenty years. The new engine was not even broken in yet!
I started fettling it and it wasnt long till I experienced the same problems as Leo had. I struggled to find the problem and finally, on the advice of several club members, replaced thecLucas generator with a new charging unit. This did not fix the problem.
Finally one night I was out on the bike and noticed sparks between the headlight switch and the headlight. This only happened at a certain rpm (vibration) and not every time. The headlight switch was faulty. This was the problem all along!
Now if the bike had been wired up with a proper fuse box and individually protected circuits for lights, horn, charging, igntion and whatever else, Leo would have blown the fuse for the lights and known right away that the problem was in that circuit. It would have been a 5 amp fuse, so it would have blown easily and probably not drained the battery first. He would most likely not have been stranded all of those times. On top of that, either auto marine elec or John M would have found the trouble in the light switch early on. And Leo would have had 20 years of fun on his Vincent after spending all of that money and effort on it rather than 20 years of agony.
But I would not have been able to pry it away from him!
So in this instance, the one fuse wiring job was quite helpful to me!
Glen
