rare rectifier

[angelo]

New to this site it looks good. I have a 2 stroke dirt bike, the power valve cuts in at 7000rpm operated by a solonoid recently it has been causeing the lights to dim as it operates, maybe it is shorting inside, I ignored this as it was working ok otherwise. On friday the bike stopped charging...
I am fairly certain that my regulator/rectifier is cooked, there is no out put voltage at the +output, but lots of heathy AC going in.

the simple answer is to replace it, but the bike is a bit rare and a replacement is expensive, also my credit card is maxed from xmas so I would rather pay cash in london if poss.

As the unit is very basic, I am hoping that someone might be lucky and recognise the "general type" and sugest one similar but easy to find that i can solder in, or sugest a cheap generic one.

The unit is a alloy heat sink about the size of a deck of cards, it has 4 conections. 2 yellow wires seam to carry ac from the alternator and then there is a conection that has a switch symbol on it and the wire off it goes posative when you turn the key on, the last terminal is marked + and goes to the battery. the unit earths though the case.

I will inclued some photos (hope they work) it is marked "12v [14,15] 14A 30 on th base.

cheers

[stinkwheel]

Where does the 'switch symbol' wire connect to? Does it run back down to the alternator or just connect into the loom at a wire that is live with the ignition on?

Assuming it connects into the loom somewhere, it looks like a Zennor diode type in which case you could do worse than using a honda superdream type reg/rec (12 volt).

It has three yellows. Blank one off and connect the other two to your AC in.

Green goes to earth.

Red goes to the battery.

White on Black (voltage sense wire) goes to a live wire in the loom that is live when the ignition is on (anywhere, usually either the flasher relay or rear brake switch). Which I am presuming is what the 'switch symbol' one is on your bike.

Pretty much any reg/rec with a heat sink and five or six wires on should do the trick. They will all be more or less the same, three wires the same colour for the charging phases (just use two of them, blank the other off). One to the battery and one to earth. Not all of them have a 'sense' wire (if you are feeling lazy, just loop it back to the battery). The superdream type are uber reliable though.

One of these:
https://www.4-motorcycles.co.uk/acatalog/rectifier.jpg

EDIT: Check you don't have a short somewhere on the powervalve circuit first.
____________________
“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.

[stinkwheel]

[angelo]

I have seen a type of alternator that uses electromagnets and only has 2 AC wires, I take it that this type uses a 3rd (switch?) wire to ajust the output by varing something in the alternator, so i should follow that wire and make certain it doesnot go to back to the alternator before i buy a secondhand superdream unit.

if it is of any use that wire goes to battery voltage if the ignition is in the run position.

thanks again A

[finpos]

Hava a search on t'internet for ducati or rotax styled regulators - you should get some joy there.


finpos.

[stinkwheel]

[Kickstart]

Hi

That looks like one from a Gilera 125. From the description I suspect one from a Rotax 123 engined Aprilia 125 will fit and do the job.

All the best

Keith
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[angelo]

that dead right! a gilera 125 apache with a soleniod power valve i will try the aprila center

[Kickstart]

Hi

Just give Bob Wright a ring down in Weston Super Mare. He might well be able to supply you with a 2nd hand one, and also tell you if it is likely the problem is with something else.

All the best

Keith
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[angelo]

thank you, I have spoken to bob he is very very helpful he has a part, and has other stuff for this bike, his pricing is not bad, (just don't say your from london ; ) ) basicaly a fantastic result!!

unfortunaly for me credit card is at max +800 after christmas and a depressing run or no pays and cancelled jobs have complicated thing a bit so i could get a mate to buy it and pay him (tedious and expensive) and i am too impatient to wait. more importantly there is a chance the power valve solanoid blew the old reg, the sloaniod works but is shorting when on above 8000 rpm and may send a new reg the same way....a good reason to put a tough honda breaker £10 special in for now , finaly i have lots of time and would love to solve this the old fashioned way, ie combined brains. It is so great when it works!

here are some additional images in case any one is still around.....

[Kickstart]

Hi

Might be worth thinking about relocating the regulator / rectifier to a cooler location. For example the Gilera CX125 (which uses basically the same engine and electrics) has it under the head stock where there will be more airflow over it.

All the best

Keith
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[angelo]

Well well, strange stuff indeed, the regualtor seems OK, as I put in a very similar ducati one and it to gave no +DV output, what is more confusing is that the AC is totaly ok, i put a bulb across the two yellow wires from the alternator and it gives a bright light that get brighter with revs??????????????????? ahhhhh

AC in nothing out, maybe a wire is disonected somewhere else? in the alternator may be the earth?

any one with some expirence here?

[Kickstart]

Hi

I will check the manual in a moment.

However not sure on the Gilera system but on the Aprilias the AC voltage is ~45V and I would expect it to be about the same. Wouldn't that blow a 12V bulb rapidly?

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[angelo]

yeh unregulated the voltage will burn a bulb out in a few seconds, but during my test i just bliped the throtle, and pulled of the wire before i roasted the bulb. I tested it that way as a AC voltmeter show voltage but somtimes alternators give voltage but no useable current.

can you give me a link to a workshop manual or mail me a file? I found this diogram on an italian website.

[Kickstart]

Hi

The English copy I have seems to have fairly random pages, the full Italian manual (CX125) is at Charlottes work. Sorry.

Bits it says. Check the alternator stator by checking for continuity between the 2 wires going to the regulator / rectifier (required). Also check for continuity between either of those wires and earth (must not be there).

To check the regulator / rectifier:-

"Connect the red probe of the tester to the terminal of the (+) marked regulator (terminal for the red / black cable) and earth the black probe on the regulator casing; the resistance value will be infinate (needle dead at the bottom of the scale).

Connect the red probe to the first or second terminal at the regulator for the yellow cable and earth the black probe on the regulator: the same resistane value of infinate is obtained.

If the diodes are working properly the ohmmeter indicator will not move. If it does this means the diode in question is short circuited.

To check whether one of the diodes is open circuited, repeat the same operation inverting the ohmmeter probes this time and ensuring that the instrument reads a resistance of around 1000 ohms or 5000 ohms using the ohmx 100 scale".

All the best

Keith
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[angelo]

trying it now

[angelo]

it passed

the values for the infiate tests were correct, the other way around the values were very losely around 1000
701 for 1st yellow
698 for 2nd yellow
1586 for the + red and black

now i just need to try the generator wires.

[Kickstart]

Hi

One thing that is worth checking is for a decent voltage between earth and the charging wire on the regulator / rectifier, to count out a break in the wiring.

All the best

Keith
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