I'm in the process of bringing a '71 R75/5 back to life after a wiring harness meltdown several years (and two owners) ago. I'm told that a common cause for this failure on the early /5's was the lack of fuses in the electrical system and that the problem could be corrected with two fuses in the correct placement. My question is: what size fuses and where?
All help/guidance/direction appreciated as always.
Viejo
OK David, Time for Some Electrickery !
As I don't know your level of experience in Airhead electrical; here's a few things to add to your knowledge base.
As you wade into the 'bucket of snakes' in the Head Light Nacelle, it's best to understand the Wiring Color Codes for easy recognition and troubleshooting. The Colors are: BL = blue, BR = brown, GE = amber, GR = grey, GN = green, RT = red, SW = black, WS = white. Individual wires are either solid colored as in: GN, or colored with a running stripe like: GE-WS.
The conductor size is shown in square millimeter area: 0.75, 1.5, etc.
It is critically important when working in the Head Light Nacelle, as well as when removing the Front Engine Cover, to DISCONNECT THE BATTERY !
The converting of an unfused Slash 5 to a fused Slash 5, centers on three(3) Terminals(T) on the circuit board type Ignition Switch: T-56, T-58 and T-15.
On your 1971 R75/5, T-58 will have two(2) 0.75 GR wires: one(1) powers the Parking Light in the Head Light Nacelle; one(1) powers the Rear Tail Light/License Plate Light. T-56 has one(1) 0.75 GE-WS which powers the two(2) Instrument Cluster Lights.
T-15 has three(3): one(1) 1.5 GN which directly powers the Ignition Coils via the left hand coil and, branches off to a 0.75 GN to power the Foot Brake Stop Light Switch; one(1) 1.0 GN which powers the Horn and branches off to a 0.75 GN to the Starter Interlock Relay; one(1) 1.0 GN which powers the Oil, Neutral, Charge Lights and, the Turn Signal Flasher.
Here's how to add the fuses: remove the two(2) 0.75 GR wires from T-58; remove the one(1) 0.75 GE-WS from T-56 and combine them together at the output side of an inline, cylindrical glass 8A fuse, automotive style holder. Install, ideally, a new 0.75 GR wire from T-58 to the input side of the fuse holder. This protects the Front Parking Light, Rear Tail Light/License Plate Light, Instrument Cluster Lights. I highly recommend using a permanent, black, fine-line marker to convert the solid color GR into a GR-WS wires at the fuse output side, making them striped lengthwise for as far as possible. Someone in the future will sing praises for your effort during troubleshooting !
Now, T-15: remove the two(2) 1.0 GN wires; one(1) powers the Oil, Neutral, Charge, Turn Signal Flasher; one(1) powers the Horn and via a 0.75 GN, the Starter Interlock. Leave the remaining 1.5 GN attached at the Ignition Switch circuit board however, the one(1) 0.75 GN that branches off at the Ignition Coil to the Foot Brake Stop Light Switch, must be removed at the Ignition Coil female spade plug connection from the 1.5 GN wire. A new female spade plug connector must be installed on the 0.75 GN wire, so it can connect to the Starter Interlock T-15, double male spade plug.
Install a new, 1.0 GN wire at the Ignition Switch circuit board T-15, nested with the 1.5 GN wire, and run the 1.0 GN to the input side of another inline, cylindrical glass 8A fuse, automotive style holder. The two(2) previously removed 1.0 GN wires at T-15 will be installed on the output side the fuse holder. This protects the Horn, Starter Interlock and Foot Brake Stop Light Switch, Oil, Neutral, Charge Lights, Turn Signal Flasher. As I mentioned above, using the marker, place a lengthwise black stripe on the output wires of the fuse holder to designate them from GN to GN-WS.
I have pictures available of the unfused and fused Slash 5 wiring diagrams, concentrating on the Head Light Nacelle, that I can email you separately.
Don ©
Erratum: by placing a black stripe on the GR and GN wires at their output from the fuse holders, that designates them to GR-SW (grey with black) and GN-SW (green with black).
my apologies, don
Hola Don!
Thanks for the timely reply and great direction. I'm a fairly competent Airhead wrench but electrics have always been the weak card in my deck and this is the oldest Airhead I've waded into (previous oldest was my '76 /6 which had the next gen ((fused)) wiring harness following the /5 series).
Your guidance below is extremely well presented, and, as I follow directions fairly well, that should have me safely on the road to a vastly improved electrical system.
I would definitely appreciate the wiring diagram images you noted in your response- [david-barnett@att.net].
Mil Gracias,
Viejo
For the most part I agree with Donald's writeup. But allow me to add some thoughts....
1. Type Of Fuse
I strongly disagree with the suggested cylindrical glass fuses. And the conical tipped German fuses aren't any better. Cars stopped using both these type fuses decades ago, and for a VERY good reason. If you intend to go through the trouble of adding fuses, then add the very latest technology by utilizing "flat pack" fuses. These come in 3 physical sizes, and the smallest (called Mini Blade) work very well on Airheads.
Not only do the fuses make a much better electrical connection, but they are color coded so that you don't fumble around trying to read the inscribed current rating in the twilight on the side of the road. And if needed... special versions are offered that light up with tiny LEDs when they are blown.
The best part is you can buy accessory Mini Blade fuse holders that are water-proof. These are "in line" fuse holders with a small length of wire already attached. In many situations, you can simply add you own crimp-on connectors and add them to the system without any cutting or soldering of the OEM harness.
2. Placement of Fuse
A. For many situations and for many reasons, it is often better to add a "main fuse". A single 20A fuse can be added back at the battery to the ~14 AWG Red lead that attaches to the Positive battery post. This addition calls for soldering and heat shrink tubing to protect the splice, but the entire harness is now protected from Airhead flambé.
B. It's a very good plan to fuse each accessory separately. If you add heated grips, a GPS, extra lighting of any type, and/or a phone charger outlet... then these items often are the cause of a short circuit. Putting the whole machine out of commission (forcing you to stop on the side of the road) simply because your music source wiring has a short simply doesn't make sense. The rule of thumb is to use a fuse 2X what the device actually uses. For instance, if your radio draws 1A, then protect it with a 2A fuse.
C. If your Airhead has a fairing (either as OEM or added), the stock wiring has no protection for expensive dashboard items like the Clock. A short circuit within the clock will burn up the fairing harness as well as the main harness without the addition of a 1A fuse. Therefore, be aware that ALL electrical items aren't protected on ALL models, just because you follow the OEM fusing plan.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
For the most part I agree with Donald's writeup. But allow me to add some thoughts....
1. Type Of Fuse
I strongly disagree with the suggested cylindrical glass fuses. And the conical tipped German fuses aren't any better. Cars stopped using both these type fuses decades ago, and for a VERY good reason. If you intend to go through the trouble of adding fuses, then add the very latest technology by utilizing "flat pack" fuses. These come in 3 physical sizes, and the smallest (called Mini Blade) work very well on Airheads.
Not only do the fuses make a much better electrical connection, but they are color coded so that you don't fumble around trying to read the inscribed current rating in the twilight on the side of the road. And if needed... special versions are offered that light up with tiny LEDs when they are blown.
The best part is you can buy accessory Mini Blade fuse holders that are water-proof. These are "in line" fuse holders with a small length of wire already attached. In many situations, you can simply add you own crimp-on connectors and add them to the system without any cutting or soldering of the OEM harness.
2. Placement of Fuse
A. For many situations and for many reasons, it is often better to add a "main fuse". A single 20A fuse can be added back at the battery to the ~14 AWG Red lead that attaches to the Positive battery post. This addition calls for soldering and heat shrink tubing to protect the splice, but the entire harness is now protected from Airhead flambé.
B. It's a very good plan to fuse each accessory separately. If you add heated grips, a GPS, extra lighting of any type, and/or a phone charger outlet... then these items often are the cause of a short circuit. Putting the whole machine out of commission (forcing you to stop on the side of the road) simply because your music source wiring has a short simply doesn't make sense. The rule of thumb is to use a fuse 2X what the device actually uses. For instance, if your radio draws 1A, then protect it with a 2A fuse.
C. If your Airhead has a fairing (either as OEM or added), the stock wiring has no protection for expensive dashboard items like the Clock. A short circuit within the clock will burn up the fairing harness as well as the main harness without the addition of a 1A fuse. Therefore, be aware that ALL electrical items aren't protected on ALL models, just because you follow the OEM fusing plan.
Hope this helps.
Wob,
Thanks for the response and info. My /5 is going to be kept as bare bones as possible (my '03 K1200RS provides all the hi-tech nightmares I need for now.... with the '94 K75 running a close second) as I'm trying to get back to why I started riding motorcycles to begin with.
Fusing the 14ga red from the positive terminal of the battery is definitely on the list.
Cheers,
Dave
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