3 phase alternator upgrade

Can you take a photo of the alternator, reg/rec and wires inbetween. I,m struggling to understand your description!

Mark,

The regulator/rectifier should have five wires, three for the alternator stator (possibly all yellow), and  the other two might be black and red.

Hi Mark

Have you bought a new regulator/rectifier to go with your three phase stator? You must have a three phase regulator. I think you are trying to connect your old two wire regulator? or have I missed some detail?

Norm

Sounds a bit like the previous owner rewired and decided to use twin core for each alternator lead. I used a doubled up wire to connect battery to earth because I didn't have a big enough single. Since it sounds like you have four wires to do the job of three you should be OK but only if the wire size is big enough to carry the current.

Your photo 1 shows the old two wire alternator connected to the wiring harness

Your photo 2 shows the  wiring harness to the original plate rectifier.

You need to study the wiring harness diagram, understand where all the relevant wires go and see what wiring can be reused.

A photo of your new components would be helpful.

fitting a 3 phase alternator and a modern Reg/rectifier tidies up the wiring somewhat as actually there are less wires involved to fewer components I.E. two components to connect as against four with the original system (alternator, rectifier, and the two zeners)

Thanks Mark, I now understand - you have shown the old two cables for alternator and rectifier, but have a three wire stator and regulator you want to fit.

I think the reason you see pairs  is because there will have been two pairs (WG and GY?) connecting to the alternator and then splitting to the old rectifier and zener diodes. We need to check Mark that the zener diodes have already been removed by a previous owner and a COMBINED regulator/rectifier fitted. Or, if the zeners are still fitted to the footrest plates then you need to do some more substantial rewiring - essentially three new cables connecting alternator to new three phase regulator (can be yellow), new regulator earth (red) and live feed (brown/blue) connecting to a fuse and then the battery, and remove the old zeners and rectifier. You also need to work out where to mount the regulator.

Cables are normally rated in cross sectional area, which is not simple to visualise. If you cut away the insulation from an end then a 1.2mm diameter (1mm sq area) copper cable bunch is about 16amp (lights, etc.), 1.7mm (2.0mm sq) is 25amp and 2.1mm (3.0mm sq) is 33amp. The 1.7mm diameter will be enough for each of the three phases, while the 2.1mm diameter is best for connecting the regulator to battery, earth and then fused at 25amp.

I have rewired a few bikes but I am only an amateur and anyone else is welcome to have their say.

First, understand what your new system will make redundant, you'll be surprised how many connect a modern rectifier regulator and still leave the zener connected. 

Once you have established the above then wiring in the new system will be easy. If the stator is a new Wassel item it will not easily fit a MK3, the old LAP version fitted nicely. 

You might need to space it out a bit, but check the outer chaincase will fit. If the stator fails Wassel will not warranty it when used on a MK3. 

Using a RM23 stator, mosfet rectifier and BSM, makes the 3 phase upgrade redundant these days. With Tri Spark ignition it will start with the battery disconnected and no blue capacitor either. The BSM shows green on tickover, the old rectifier in the same setup could not even do that. It makes efficient use of what the RM23 stator outputs, and keeps a 14Ahr battery well topped up. 

The cables in a traditional Commando loom are 8.75A (call it 9A) 14/030. You can use 'modern' thin-wall which says it will carry more current but in fact it carries the same current but the thin wall runs warmer hence does not melt as soon as the 9A cable does.

The two wire we see here are to the Zeners on a MKIII as the Zeners are on the AC ie alternator side of the rectifier. Yes it would be ok to split one pair out to get three wires BUT do make sure you spilt out both end of the same wire. Also running three new wires from the alt. to the reg. would be a better job.

Any further questions give me a call 01953 884681

The latest 3 phase stators from Lucas don't fit a MK3, you'll need to make spacers and / or remove some of the encapsulation material. Wassell will not warranty it either as it was not an original aprt on a MK3.  

All the original cables on our bikes are rated at 9AMPS ie it is called 1mm (but you can't measure it) I sell this and I even started the Battery Status Monitor BSM.  ALL our rotors are the same since the mid 1960s ie 74 mm dia 19mm bore. if they are old they do loose magnetism, so a new rotor might be enough to get your alternator back into good working order. The MKIII had a high output single phase unit with two Zener diodes (on the Z plates) and a very odd half bridge rectifier-see my web site.

The thread might be 5 years old, but it is still something that crops up. The RM23 works just fine if you use a modern rectifier / regulator, charge warning light / battery status monitor and LED bulbs which are legal to use on motorcycles. The MOT regulations for motorcycles no longer mentions bulb but 'light source' which must cast a beam that meets the requirement, the light source can be anything. 

I used the above set up and have proven many times that even when starting the MK3 on the starter the BSM shows green after a couple of minutes. The last 14 amp battery I had fitted lasted 6 years with this set also, it would not have lasted if the charge was insufficient. 

There are Lucas own testing results that show the output of both, and it was not enough to convince me it was a worthwhile upgrade. Better efficiency can be had by maintaining the harness and charging circuit to reduce losses. 

There is absolutely no need to fit a 3 phase stator to a MK3. 

HIGH OUTPUT 3 PHASE is mentioned above. in fact the Higher output 3 phase has the same output as the RM23 (High output Single phase as MKIII) with regard to maximum power. There was a Medium output 3 phase used on Triumphs in the early 80s (47252 if you want to know).
But no 3phase was ever fitted to any Norton so another 'raspberry' to the originality freaks.

What Stan says above is exactly what Triumphs did, fitted a 150W alternator and used a 100W zener as the regulator!!! How can this be you ask? the ignition draws some 20W and the battery charging takes a similar so we use up 40W at least, losses in the wiring makes the 150W 3 phase usable with the 100W zener. By the way I have the 3 phase rectifier for sale.
By the way what is 'Genuine Lucas' ? Lucas as a company failed (along side the British Motorcycle industry) in the mid 80s, the name is used by the Wassell empire.

Seems some are still using zeners with modern rectifier regulators, not sure why as there is no need. As for a 3 phase generating more current at lower revs than a RM23 is somewhat of a red herring. I get 14.3v  at the battery at tickover from a cold start using an RM23, that alone suggests that the current and voltage thus the power being generated is more than adequate. This on a bike that used a Chinese sprag for 6 years and still working fine. 
The extra hassle to fit it to a MK3 for no extra return is not worth it. The RM23 is more than adequate for the MK3 with electric start, so massively adequate for the pre MK3, even with an Alton kit. After 30 years of MK3 ownership, and 10 years in the trade do you not think I would have fitting one and be singing it praises it was any better than the RM23. 

When i bought my Mk3 it had a 3ph stator fitted and along with a box of 'spares' These would be better called  'Duds'  This lot included a sparx stator without the lead, it had broken off next to the potting compound. If that sparx stator had been fitted to my Mk3 earlier in its life it would mean Mitzi is now on her third stator at least, maybe more.
One of my pet gripes is that the Lucas (original and later ones) used insulating sleeving that hardens in the primary case, (the hot oil leaches the plastisizer out of the sleeving) it then cracks, lets the hot oil get to the green yellow and green white wires and the same happens, they crack and now you have bare copper wire showing. The rubber grommet in the primary case goes as hard as concrete as well, makes it a bit of a juggling match when removing/replacing the primary drive, trying not to flex this lot too much. The photo is a spare stator with the lead repaired and clipped in place.
My usual trick when removing a well used stator from a bike is to pour a kettle full of hot water over the inner primary case, you can then wiggle the lead and grommet out as they are now soft. A hot air gun works as well but you have to be careful as overheating the wires is easy done. 
Use a new grommet when refitting the stator.

Fitting one additional wire is no hassle if the new style stators were a straight swap mechanically for the RM23. The old versions, usually the old brown LAP version would fit straight on, but the new Wassell Lucas ones don't. Wassell are new to the Lucas trademark, prior to them using in recent years it was LAP who gained the Lucas tooling but not the right to use the trademark I believe. My bike has been through several stators over the years, but I do have the drawing for the stator. They were fitted with a 2 wire high output stator, which was introduced in Jan '74. 
 

The MK3 Ultimate Ride brochure says high output as above, which all ties in nicely with the MK3 factory build book. A lot was carried over from one publication to another, just like the oil capacity for the fork leg. 
Considering we have a huge number of Commando's using Alton kits with 150W alternators, the 3 phase stator argument has been pretty well put to bed. Many using the Alton kit use a battery which has a little bit more capacity than a MK3 uses and it all works just fine. 
Most would be better off reducing the electrical losses in their wiring than fitting a 3 phase stator.