electrics thread/link please

[namibchris]

Greetings from a stormy Namibia. Can anyone direct me to a link/thread in which the pros/cons and how to's on a 12-volt neg ground conversion for a 750 Commando are discussed. I am inherently suspicious of a positive ground system, (it took years to get used to driving on the wrong side of the road here) and I would like to upgrade the electrical system to something more modern and have a bloody bright headlight to boot.

 

[swooshdave]

search.php



:mrgreen:

 

[maylar]

The only reason I changed my Norton's earth polarity is so I could use commonly available LED bulbs in my blinkers. My 65 watt headlight didn't get any brighter.

 

[rvich]

Might try this one:

negative-ground-conversion-t6529.html?hilit=negative ground

Are you planning to run lots of modern gizmos? Or just want a good charging system with a bright headlamp? Most DC items don't care about polarity. Any device that does is often not grounded through its case. As long as you don't attach something to the bike that is case grounded (thus it is isolated) then you can hook its polarity as needed. Some items are more difficult to achieve this with than others. I have not messed with LED turn indicators. I suspect it could be done but since it is common even with a two wire unit to case ground lights they would have to be completely isolated from the frame. (This is sure to start an argument, which seems the best way to get info some days!)

Russ

 

[Hobot]

Two main items to deal with on negative ground conversion, Blue Cap electrolytic can has some polarity preference I'm told and assimulator, but otherwise just switch battery connections.

negative-ground-conversion-t6529.html

Alan Dawes wrote:

According to my old text books, the change-over to positive earth began in 1936 in British cars and was primarily to reduce sparking plug voltages. The sparking voltage is appreciably less when the central electrode has negative polarity. (Why?) Also when the central electrode is negative, the corrosion and burning is confined to the relatively much larger area of the metal shell. This prolongs plug life. A similar argument applies to rotor arm erosion in distributor ignition systems. In positive earthed systems, the erosion occurs to the relatively large contacts in the cap rather than the rotor arm. The positive earth practice continued until the mid 60s. For example, in 1965 SMMT data sheet EE-14D recommended the adoption of negative earthing. (Why the witch back?) Cheers Alan

While that may technically be, the fact is that most brit bike factories changed from neg earth dynamo and regulator to pos earth dynamo and regulator in 1953 or 1954 = 3 or 4 years before the introduction of alternators for most manufacturers.
Whats more, it was only denoted by carefully studying the wiring diagrams
in the appropriate maintenance manual - or noting what wire was connected
to which terminal on the battery !!! Cheers, Rohan.

The reason for the shift from negative ground (dynamo) to positive ground (alternator) is that original two 1953-4 era producers of recitifies produced products that had diametrically different charging paths. Westalite charged from the outer ring via a wire , Sentercel charged thru the center attaching post (aka positive earth). Due to the obvious ease of wiring Westalite to charge like Sentracel but not vise-versa positive ground was adopted as the standard.

 

[rick in seattle]

It's only slightly more complicated. I did it on my Mk3 and posted the results:

negative-ground-conversion-commando-mk3-t8240.html

If you're running an EI, you'll have to change the hook-up; all EI suppliers provide instructions. The blue cap is electrolytic and polarity-sensitive; be sure the positive terminal is connected to +12v and that the case is isolated. Solid-state assimilators have to be swapped out for negative ground units; I don't know about older analog versions. You could do without, or install one of the many after-market sensors available. The OEM zeners are polarity-sensitive and will not work; you can either replace them with a regulator/rectifier box, or, as some forum members stated in the past, find more recent Triumph zeners built for negative-ground systems. Single-phase boxes are less than 70 bucks. All automotive relays, to my knowledge, work with either polarity. So, with the caviats above, switch the battery wires and let 'er rip. Be aware that the original red wires will be grounded (negative) to the frame, while after-market devices will have black ground wires. Original blue-brown wires will now mean +12v, but after-market hot wires will be red. Clear? You'll need a very clear new schematic to troubleshoot.

 

[slupdawg]

Here's a general schematic I've been working on. Feel free to use it:

 

[pelican]

:lol: :lol: :lol: :lol:

 

[batrider]

Wonderful work! This is just too funny!

 

[rvich]

Here's a general schematic I've been working on. Feel free to use it:

This has brightened my day considerably! So what happens when you reverse polarity on the center of the sun? You go into interstellar overdrive?

 

[namibchris]

Here's a general schematic I've been working on. Feel free to use it:

Thank you for the great Diagram, that will help hugely. Is it better to lick your fingers before grabing the ends or do it dry?

 

[namibchris]

So let me get this straight. There is little or no improvement in headlight brightness and the main benifit is the ase of using LED indicators. Otherwise little overall change in how the electrical system will work. In which case it seems to me given my overall goal of solid performance it makes more sense to upgrade ignition rather then polarity. The wiring harness on this bike is a mess so I was simply going to buy a aftermarket harness.

Any thoughts on a reasonably priced ignition replacement/upgrade?

Still raining her in the desert.

Chris in Omaruru

 

[rx7171]

If you are wanting to upgrade to a brighter headlight than the 4540W high beam you can go to a 60/55W halogen.

http://www.danielsternlighting.com/prod ... ducts.html

In looking down the lamps available I see they have H4 halogen bulbs on P45t base
Upgrade your vintage European headlamps to modern-car light levels! These updated halogen bulbs (above left) fit and work correctly in all 1950's through 1980's European high/low beam headlamps originally equipped with tungsten R2 bulbs (above right). Light output is much higher, life is much longer.

45/40W (original tungsten wattage) Narva: $11/ea

60/55W (standard halogen wattage)Narva: $14/ea

100/90W Narva: $20/ea
130/100W Narva: $22/ea

 

[slupdawg]

Here's a general schematic I've been working on. Feel free to use it:

This has brightened my day considerably! So what happens when you reverse polarity on the center of the sun? You go into interstellar overdrive?

I'm hoping for warp factor 2. I may not catch hobot, but I think I'll come damn close!

 

[gtsun]

Hey Slupdawg, I need your help. I rewired my neighbor's kid's mini bike using your diagram but in Lue of Holy water ( hard to get & could be dangeouse ) I used a good single malt scotch.. The bike started first pull but than the bike & the kid vanished in a big blue flash & left nothing but a burn out skid mark & smoke!!! I won't miss the kid but his step dad wants the mini bike back. Any ideas?

 

[rvich]

Steadfast Cycles sells a halogen 65/55w Lucas style bulb for 22.00 bucks

http://www.steadfastcycles.com/cart/ind ... baaaa8aeec

As for the wiring harness. Is it a mess because a previous ownder hacked it up or is it because all the connectors are broken and need replaced? Or other?

 

[slupdawg]

Hey Slupdawg, I need your help. I rewired my neighbor's kid's mini bike using your diagram but in Lue of Holy water ( hard to get & could be dangeouse ) I used a good single malt scotch.. The bike started first pull but than the bike & the kid vanished in a big blue flash & left nothing but a burn out skid mark & smoke!!! I won't miss the kid but his step dad wants the mini bike back. Any ideas?

Well, I'd like to point out that this a general wiring schematic and I know that many people on this forum can and do make modifications and/or substitutions. These can have unintended consequences. I wonder if perhaps the single-malt could be substituted with a cheap blended variety? As for getting that bike back, well I suppose it boils down to how resourceful and capable that neighbor kid is that will determine whether or not you see it again. The only thought I have is that mini bikes are plentiful and cheap. Any chance of doing a switcheroo? Maybe he won't know the difference!

 

[JimC]

Slupdawg, I don't know what you do for a living, but if you are not being paid for writing comedy you missed your calling.

 

[namibchris]

Steadfast Cycles sells a halogen 65/55w Lucas style bulb for 22.00 bucks

http://www.steadfastcycles.com/cart/ind ... baaaa8aeec

As for the wiring harness. Is it a mess because a previous ownder hacked it up or is it because all the connectors are broken and need replaced? Or other?

It's a mess, cut, hacked, taped, color changed, I hate @#$% that gets the residue from electrical tape on it. I mean I am capable of building one with a schematic or proper diagram that does not involve holly water or plutonium. But for the price of a new one which seems cheap to me, I'm thinking I would rather put effort elsewhere....

 

[maylar]

So let me get this straight. There is little or no improvement in headlight brightness and the main benifit is the ase of using LED indicators. Otherwise little overall change in how the electrical system will work. In which case it seems to me given my overall goal of solid performance it makes more sense to upgrade ignition rather then polarity. The wiring harness on this bike is a mess so I was simply going to buy a aftermarket harness.

Any thoughts on a reasonably priced ignition replacement/upgrade?

Still raining her in the desert.

Chris in Omaruru

The first thing to think about is replacing the alternator and charging system. The hot setup is a 3 phase stator, 180 or 200 watts. Search here for "Sparx" or "3 phase" and you'll see what others have done. When you replace the harness and install a new charging system you can make the choice of positive or negative ground. The ignition choices are numerous.. Boyer is probably the cheapest. Sparx, Pazon, Lucas, and Tri-Spark are other brands. Everyone has their favorite, and they all work.