Topic: 400 Four Electrics

[sammy5150]

I have rebuilt my 400 Four to the extent that its currently in a happy state whereby the engine is looking very sparkly in its frame, with the electrics my next challenge. So far so good,  Im enjoying every minute spent in my man cave.

I know very little with regards to motorcycle electrics, however the whole point of my rebuild is to learn about this stuff so that I do know for my next build.

I could easily take my pride and joy to the local garage to have the electrics sorted but what would I gain from that ? I appreciate a good challenge, so far I have had numerous,such as removing the c clip from inside the brake master cylinder, that didnt take long to remove.............. Even trying to locate the colour coding on the main bearings that feel out on splitting the crankcase I manage to crack eventually.

Therefore  Im looking for some advice as to the best place to start. My main interest is particularly how or what to upgrade to improve performance and reliability, what should I purchase at great expense or what should I stay well clear of ? I don't have a salvaigable wiring loom, would it be madness to try and build my own ?

Thanks in advance for any direction you may be able to offer

[TwoTired]

Why do you think your existing wire loom is un-salvageable?

Unless the insulation has been exposed to the sun and is now cracked, brittle, and flaking, the wire core is still as good as the day it was made.  This core wire has more and smaller strands to allow it to withstand vibration an  frequent bending.  Robotic wiring also has this property.  If it is dirty, then clean it, and it will look renewed.

As for upgrades, I say replace or correct what has failed, rather than try and re-engineer a system that is still proven to work well after 40 years.  Just because it is old doesn't mean it must be discarded, despite what modern marketeers and salesmen wish the masses to believe.

The best "upgrade" i can think of for the electrics it to clean each connector pair bright and re-assemble with dielectric grease.  Same goes for internal switch contacts and fuse contacts.

[sammy5150]

Thanks for replying. Unfortunately I dont have the original wiring loom, I have seen new ones are available from David Silver here in the UK but am considering trying to build a new one myself.

[Bodi]

Recreating an original loom will be more trouble than you might imagine, and probably cost more than the DSS one unless you value your time at well less than zero (learning always has a cost). Having the original wire colors (like the DSS loom does) is very helpful. Finding short lengths of the various colored wires isn't exactly easy. Purchasing normal spools (usually 33M minimum) costs a bundle with so many colors, and the striped wires will be very hard to find. Most of the bullet connectors (try to find the 4x female!) are available... but those clear plastic insulating sleeves are going to be a challenge.

You can make a simplified loom fairly easily that skips a lot of the "bells and whistles" of the stock system. The multi fuse parking/tail light circuit can be simplified, the starter interlock can be ditched. You only need ignition, head/tail lights, horn, brake light, and maybe turn signals to run and be legal. I would want an oil light as well. A neutral light is nice but not indispensable.
Look at chopper wiring diagrams for ideas ("Santee Box").
The engine, rectifier, and ignition connector shells and their terminal inserts are available online or you can improvise.
TT mentioned the wire to use. Home wire, solid or stranded, is way too stiff and not made to bend repeatedly. Normal automotive hookup wire is not meant to be flexed the way the harness does: it will work harden and break if you try to use it around the steering stem. You should use robotic (or "machine tool") wire with a lot of (around 100?) small strands, it's made to be flexed almost continuously. You can get "wet noodle" wire (several hundred extremely fine strands with rope twisting) online or at hobby shops-  but it's more flexible than you need, very expensive, and a bugger to get terminals onto.
Most harness wire should be 16ga, the starter power and battery cables should be 8ga. The OEM wiring is a metric size that is a bit bigger than 18ga and a bit smaller than 16ga.
I would use 14ga wire for the rectifier output wire - plus the headlight and ignition coil wiring as these carry the most current and are most susceptible to voltage drop with reduced light and spark energy respectively.
- Install fuses on all power circuits except the starter power and rectifier output!
- Include a kill switch near a handlebar grip! You don't need it very often but will truly miss it if you do... and don't have one.