Alternator!

[GreenMachine]

Hey guys,

Am buying a solid state reg/rec today, and have a question - the alternator in a '71 T500R is three phase, isn;t it?

This is the reg/rec i'm thinking of buying:

http://cgi.ebay.com.au/Regulator-Rectif ... 20b6ba3c07" onclick="window.open(this.href);return false;

Any advice appreciated!

NH

[jabcb]

No, its a two phase alternator with a lighting coil.

For T500 wiring diagram see:
http://smokeriders.com/diagrams/index.p ... Wiring.gif

For an example of the alternator wiring & rectifier, see:
http://smokeriders.com/diagrams/index.p ... T250_A.gif
The GT250 is wired up somewhat differently, but the diagram shows the rectifier & alternator details.

Several suppliers have rectifier/regulators that will work. Not sure which one is the best buy.

[rbond]

Try the guy in Oregon or Electrex in England.

[GreenMachine]

Thanks guys... It seems you can only buy single phase or three phase reg/recs... Anyone have any idea which to use?

NH

[tz375]

There are two basic types of regulator one for permanent magnet types and one for electro magnet types. IIRC the 500 is a series of pairs of coils with a permanent magnet.

When the headlamp is ON it switches in the NIGHT coils to charge stronger. So it's really just a simple single phase design with three pairs of coils in parallel. One pair is direct to teh R/R and the other two pairs connect via the h/l switch.

Of course I could have that all back asswards, so please check with a 500 tech.

[uzidzit]

The three phase will work, with single triple or two leg ac. at worst on a bike like the gt500 (two phase charge system) you will just have a spare yellow wire. ona single phase (read old brit and early japanese, old harley) you just have a single phase to deal with so a simple zener diode is ok. or you will have two left over yellow legs. tape them up and use them as spares. oregon has what you need without the fuss. my gt500 is running a simple full bridge rectifier from radio shack $3.94plus a heat sink. (get a 50v 25a full bridge rectifier) it will do the trick

[GreenMachine]

Thanks again guys. Have purchased a three phase one. According to the wiring diagram linked above and my bar-room logic, the standard alt has two outputs going to the factory regulator and rectifier and one output going directly to the headlight unregulated/rectified. This (in theory) lines up with the three wires on my new reg/rec assembly. Unless it doesn't and it all catches fire. Which it won't because I'm wiring in a blade fusebox as well.

Have just been on a bit of an eBay spree - new reg/rec, new solid state flasher relay, new switch gear, new fusebox and some other bits and pieces... Sweet!

[jabcb]

I hope you read this before installing a three-phase regulator/rectifier on your T500 -- don't.

Misspoke in my earlier post. You have a single-phase permanent magnet alternator with two outputs. One of the outputs is split so that it can be switched on and off depending on if you have the lights on.

One of these will work:
http://cars.shop.ebay.com.au/i.html?_nk ... ccessories" onclick="window.open(this.href);return false;

A regulator/rectifier for an old British twin will work. Just pick one that is 12v, negative ground & for single-phase permanent-magnet alternator.

Oregon Motorcycle Parts has a really nice unit:
http://www.oregonmotorcycleparts.com/VRRPM.html
See VRRPM2
I like their products & usually recommend them. The T250/T350/T500 have pretty meager alternators & this is more than you need.

For my GT250 I went with a Tympanium regulator/rectifier:
http://motors.shop.ebay.com/i.html?_nkw ... triumph%29

Whatever you pick it should:
1) have 4 wires & wire up just like your old rectifier
2) be for single-phase permanent-magnet alternator
3) be for use with a negative gound

If the regulator/rectifier doesn't have cooling fins, you should mount it to something like the frame to act as a heat sink.

[GreenMachine]

See, this is why I ask the experts!!!

Thanks mate, have called the ebay seller and asked to change the order. Much appreciated.

NH

[GreenMachine]

Hey guys,

Further to this, I'm trying to understand the function of the green/white wire going from the generator to the headlight switch. Is this an output? I'm trying to wire the bike with the low beam always on (not switched), and am not sure if this wire should now go to the reg/rec or not?

[GreenMachine]

Ok, a search on sundial has revealed that the standard headlight switch connects red/green and green/white when you turn the headlight on, to fire up the charging coil to cope with the extra drain.

Given that I will always be running the headlight, I should permanently bridge red/green and green/white. Can someone please confirm this logic?

Thanks!

NH

[jabcb]

You are correct.

The headlight on/off switch controls the lights and alternator output. Alternators with separate charging and lighting coils were pretty common. Some bikes with separate coils, like the T250/T350, didn't even need voltage regulators -- they relied on the battery to control voltage.

On the T500 connecting the R/G and G/W wires will give you full alternator output all of the time. Will also provide a smidgen more alternator output since you are shortening the wiring between the lighting coil and the rectifier.

Since you've bypassed the headlight on/off switch so that the headlight is always on, you should also bypass the switch so the lighting coil is always on too. Otherwise you might run the battery down because you have the headlight on, but have the lighting coil switch off.

[GreenMachine]

thanks for that mate - much appreciated!