potentially stupid wiring question

[bsquiggle]

Okay,

I've had to buy a new alternator for my CB250RS. Unfortunately, the wire colours are different and the plugs aren't wired on since the wires need to pass through rubber blocks etc before connecting the plugs. So, the old alternator has three yellow, one blue and one white. The blue and the white connect to the CDI (already replaced), while the three yellows all go together into the reg/rec (also being replaced, but the plugs are fitted, so hoping that'll be simple)

1. does the configuration of the three yellow wires matter? if so, how do I tell which to plug where?

2. The new alternator has the three yellow, but then has a black with red wire and a green wire. Which ones should these replace?

I'd really hate to fry something, since it's taken 2 weeks to get to this point.

[zorgman]

the 3 yell wires dont matter thats a 3ph alt so any way works
the other 2 are pulse and thats easy
connect them one way round and try to start bike if it coughs splutters or dont start or if it does start but engine is lumpy swop them round.
if it starts and runs smooth then its correct

[bsquiggle]

thanks zorgman - I did exactly that in the end, but since bike still not running I based it on which configuration gave me the higher voltage output (around 80 max instead of around 50 max).

Still no spark though

[www.125power.com]

Not sure about cb250 but some old 3 phase alternators where sensitive on wich way the peaks and troughs set off. For example if number 1 wire peaks followed by 2 then 3 you will have a strong spark. But if you have number 2 then 1 then 3 you get a weak spark. I have no idea how to tell the three apart, so draw a line on one of them, and two lines on the other, leave one blank do the same on the wires they are joined too and the start swapping them, the lines will help you remeber what combinations you have tried.
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[bsquiggle]

[www.125power.com]

okay thats my fault i read it all wrong i thought you had a really old 3-phase coil.......
you gone about it the right way measuring wich configuration give you max volts and still no spark at all??
Try wichever one gives you best amps, and while the mutli metter is out check the connection for C.D.I to plug (not sure if it will read from the nose or firing tip the firing tip most likely though).
If the spark plug cap has a resisitor in it make sure it working (again multimeter) or if it hasnt you should get a reading (from one side of the cap to the other) of somethign like 0.00-0.02 ohms.
80 volts should be enough to give at least a weak spark so check all conections to make sure everylast one of them is gettin to the firing tip.
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[bsquiggle]

I have tried it both ways - neither way gives much output to coil. Any chance I might have damaged the CDI by having the alternator round the wrong way durieng testing? only thing I can think of now. voltage from alternator has been checked at entry to CDI, as has pulser unit.

[stinkwheel]

Green is usually an earth on a honda, seems odd that there should be a green wire coming off a pulse coil.

Is there any adjustment on the distance the pulse coil sits from the rotor? They sometimes have slotted holes and you might need to move it a wee bit closer.

The reg/rec unit on that bike is pretty reliable as a general rule, it should also make light work of your alternator output so don't worry about the order of the yellows.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[bsquiggle]

The pulse coil isn't adjustable in any way, and does already appear to be working correctly - sends small voltage when I kick the bike over, resistance reads correctly and changes when kicked over. Wires are green/white and blue/yellow - and I have only disconnected them to clean contacts so no chance they're wrong. The new regulator came with correctly coloured wires and plugs, but isn't part of the ignition circuit anyway, which is what I'm concerned about right now.

Only the alternator wiring I have had to do myself, which is why I ask about CDI damage possibility - I know it has diodes in it but don't really know alot about the guts, and the manual gives only a vague idea of it's workings - shows basic flow rather than wiring of internals, which isn't enough for me to tell really, even if I had paid more attention when we covered electronics in physics. Really hope I haven't managed to do that as it'll be another wad of cash..

Have checked wire to coil at CDI and at spark plug / coil end, nothing out if coil connected, a surge voltage to around 10v when not conncted, but no apparent short as the resistances on coil are correct.

Have tried disconnecting kill switch wire completely, no difference

[stinkwheel]

CDI units are a black art as far as I am concerned. Difficult to test too because they need an 'active' tester to trigger the transistors and such inside them.

That said, it is probably something stupid like a broken wire or a bad connector somewhere.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[bsquiggle]

between the alternator and the spark plug coil, there are only four connections, and two of them are at CDI. I've checked all wires for continuity and earthing and they're all correct