What size wires and fuses?

Hi Karl - ref the fitment of an Alton Electric Starter - I have one fitted to my Commando - it works superbly. You mention fitting a new alternator when you fit the Alton starter. FYI a new alternator is supplied as part of the Alton kit (together with all the required starter cabling, solenoid etc.). The alternator is of a special 'slimline' design rated at 150w - no other alternator is really suitable as the width of other types would preclude the starter fitment. i.e. don't buy any other type.

Previously Chris Grimmett wrote:

Cable in the UK is rated as follows:- 0.50mm2 - 3A 0.75mm2 - 6A 1.00mm2 - 10A

There is no reason why you cannot use standard mains cable rated at the appropriate current if you wish. I find 7-core trailer cable very useful indeed for rewiring bikes. The central core [2.00mm2 White] is usually rated at 17.5A and the remaining 6 conductors are rated at 8.75A each. I use that white central core as the earth back to the battery. All this means that you are throwing the standard wiring diagram and colours out of the window, so make good notes on what connects to what. Also, use flexible twisted strand cable and not solid cable such as twin and earth as used for domestic lighting and power wiring.

I don't know the current drawn by an Alton electric start but it is going to be in a different league to those discussed below. If you are trying to future-proof your rewire now, you will need to run some starter cable of considerably higher cross-sectional area. I am taking an educated guess that the Alton conversion comes with a solenoid but you could wire one in now, fit the starter motor cables and leave them safely terminated until they are needed.

Regular readers of the message boards will know that I think chassis earth returns are a work of the devil and a failure waiting to happen. It's sometimes difficult to avoid but it was pointed out to me long ago that soldering cables is best avoided wherever possible. The heat involved can brittleise the copper and result in fractures close to the soldered area. That's why the aircraft industry settled on wire wrap years ago and the automotive industry uses crimp connections. Your alternator is unlikely to kick out much more than 190W = ca. 15A so extend its wiring appropriately; you can look at the existing alternator wire dimensions to get an idea of what is required. I find that it is a much better idea to have the various sub-sections of your bike's electrical system fused separately. If trouble occurs, it makes fault-finding a lot easier and you can then always run with the offending part isolated if an immediate repair is not possible. That's provided it's not the ignition of course. Your choice of car blade fuses is a good one. They are compact, easily obtained and come in a variety of ratings - e.g. 2, 3, 5, 7.5, 10A and upwards from there. For the the headlamp fuses, a 5A is probably OK as they always blow well over the rated value but I use a 7.5A to be on the safe side. Ignition coils and the Boyer should not need much more than a 3A and horns vary but are large consumers of current albeit for a short while - use a 7.5A or even 10A fuse. If you run a separate fuse for side lights and indicators, a 5A usually suffices. A meter will confirm the individual fuse requirements for the various parts of the electrical system.

Finally, it's not a bad idea to retain a master fuse right back near the battery itself and something large like a 35A will do for that.

Al Oz strikes again.

90% of the above information from Mr Grimmett is technically very good and worth following. But the use of any old trailer cable and/or mains cable on any vehicle is rubbish!!. I would use none of the above cables on a British Vehicle (well perhasp to lash up some speakers on a 70s car!) Cable is relativle cheap, 90% of the cables on a British motorcycle have the same current capacity so choosing correct vehicle wiring does a correct job. Every time you add wrong/different coloured cable to your bike you multiply the chances of the next breakdown sort out being horrendous. Casual wiring gives casual results. DO IT PROPERLY!

There are something like 10 basic coloured cables used on a British motorcycle. If you stick to them, then the next time your electrics break down it is very easy to sort out the problem. If the rear light fails (due to a wiring problem) then standard colours tells you it will be in the Brown and Green wire. If it is on Mr Grimmett's bike you won't have a clue which wire it is unless he is standing there with the diagram! How many of you carry the diagram?? Try remembering a few basic colours, much easier. PS Don't buy a bike from Mr Grimmett else you won't have a chance with the electrics! Keep it simple stupid.

Basic British motorcycle wiring uses 8.75 Amp wiring 14/030 while the main power feed can be 28/030 17.5amp. These days we are going over to thin wall cable!!! This is the same wiring but is rated next size up!! ie 28/030 becomes rated 25AMP. Clever huh? All this does is the same copper passes more current, gets hotter (warmer) and you have slightly more voltage drop.

Why do you want fuses in every circuit? why are we expecting faults all over the place? What are you protecting?

The only real need for a fuse is in the main battery feed, this stops the power in the battery getting into the bike and making it burst into flames. Any added fuse will be adding extra connections, wires, fuse holders etc no need. Once you start blowing fuses due to dodgy wiring it is time you sorted the thing properly.

So There'

Al Oz.

Eyop Karl, so nar tha nose,thaz bin teld ,so gerron wi it.

Good Luck,Mel.

I agree with that Al, I was just about to put a blade fuse box in mine then I thought, "Hang on, that's just more mechanical connections, more complexity, and more to go wrong!"

So I replaced all the duff wiring and connectors, and where I could, I soldered and heat shrunk the lot! Time consuming and harder to fix if it goes wrong, but far more durable.

I did however stick a 180W conversion, a "power box" (potted heat sunk regulator/rectifier), and a Pazon ignition on, to help the new brass slide Amals cope. Unlike my wallet, which is weeping quietly in a corner somewhere...

It may also be worth pointing out that if you are going on an uber fusing mission, you should ensure that all of your earthing points/wiring are good, and that all your connectors are good, and that you have no potential short circuits.

The devil is most certainly in the detail.

Personally, I would concede that perhaps the odd "zone" fuse may be useful, but not perhaps necessary.

Regards

Jack

On the subject of Land Rovers, my 1952 model has one fuse. In the Workshop Manual, it says in the event of the fuse blowing, fit a bigger fuse. I kid you not. Gordon.

People seem to worry about copper becoming brittle when it has been soldered. It shouldn't if you have used the correct soldering iron, which won't get anywhere near hot enough to affect the copper - e.g. don't use a wacking big 100 watt gun iron or a blowlamp! 25 watts should be more than enough.

My Dad was an electrician in the 1950s and early 60s- both auto and domestic -and as an auto electrician he used to be involved with HGVs, up to the "Mighty Antar" tank transporter and the old Mass Radiography mobile X-ray units. I regard him as an expert and he always recommended soldering the nipples on when using bullet connectors. Exposed wiring in bikes tends to oxidise and can end up blowing all your bulbs ifa connection to the battery gives up even briefly when you're running with lights on.

Using a proper earth wire to allelectrics is a very good idea. That way you don't need to destroy paint on your preciously expensive, stove-enamelled frame for one thing! Less voly drop too. Just keep the colour code correct (Lucas used red for positive earth 6V and 12V) You could use an earth block in the tool tray underneath the seat if you wanted, but a multi-bullet connector works too. A 2-way can have one in and three out. (3-way has 1 in, 5 out) A relay needs a seperate "earth".

Cheers, Lionel

PS. By "exposed wiring" I meant the copper core of course!

Cheers, Lionel

Hello why are you still using old tech , you all need to take a look at Electrexworld.co.uk and try out there new self generating electronic ignition and lighting system , comes all as one kit for less than £300 you can fit this a forget it , its will go on working with no fuss and its reliable only one moving part, this all fit in the alternator side , you Dump every thing that was there before, its far better than Boyer or Pazon or any other Electronic ignition system the Kit you need is STK-102D Fits Commando and Dominator Alternator Models Only , So Check this Out, Yours Anna J

Anna - are you saying that this miracle electronic ignition you mention can replace all the wiring on a bike? I wouldn't think so - this post is about wring and fuses, not electronic ignition.

Cheers, Lionel

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Previously anna jeannette Dixon wrote:

Hello why are you still using old tech , you all need to take a look at Electrexworld.co.uk and try out there new self generating electronic ignition and lighting system , comes all as one kit for less than £300 you can fit this a forget it , its will go on working with no fuss and its reliable only one moving part, this all fit in the alternator side , you Dump every thing that was there before, its far better than Boyer or Pazon or any other Electronic ignition system the Kit you need is STK-102D Fits Commando and Dominator Alternator Models Only , So Check this Out, Yours Anna J