Sparx/PMA/headlight HELP

[jkocr2]

i'm running a sparx and pma and it seems to idle fine around 1200 but as soon as i flip on the headlight the bike dies. i noticed when i put a vom on it i wasn't getting 13.2v at idle and if i gave it gas the voltage would come up but i could get it to go past 14.5 and even up into 16v! is this a trait of the capacitor? shouldn't the reg/rec limit voltage to 14.5v?

does this sound like a bad reg/rec? but even so, why would i be getting low voltage at 1200rpm..

i've read through a bunch of posts but dont seem to find the answer i'm looking for. unfortunately i havent tested the reg/rec but it was working 2 months ago when i took the bike apart for a rebuild.

 

[figure8]

Could be the reg, it shouldn't jump up much over 15v at the most.

 

[jkocr2]

if i set the idle up to 1500 then it will run the headlight/taillight/e-advance and i see a voltage around 14.2-14.5v, i'll have to double check it again tonight but i'm pretty sure i saw that number go about 15 as soon as it hit 2000rpm

 

[jkocr2]

Anyone?

I removed the sparx lastnight and tested with a battery, getting like 12.3v at idle and it maxed at 14.6v @ 3k rpm. Tested .5ohm across all three yellow wires on the stator and verified on a buddy's bike his was the same.

Put the sparx back on and getting 11.9ish arty idle with the headlight off and around 9v with it on and the bike wants to die. I did notice the rpm spike to 15.2v when I wrapped it up really quick.

Do you think another capacitor in parallel will fix this or do I just bump up the idle..any thoughts/ ideas would be greatly appreciated

 

[OakBehringer]

Last week I installed a HHB PMA & a single Sparx. I have a 55/60W headlight, LED tail light, PAMCO ignition, ultimate coil. 100% new wiring. Everything runs fine at idle (even with my high-beam on) and at speed. I can start it first kick with the headlight on.

Thus, something in your setup is fucked up. Adding a second cap is not necessary.

 

[jkocr2]

What's your idle set at? I'm running basically the same setup with the addition of an e-advance. Mine starts first kick as well with the headlight on and a neutral light and led taillight. It's the charging at idle I'm trying to figure out

So you saying my setup is fucked up is really no help...but thanks for the comment!

 

[arcticXS]

A PMA alternator, as the name implies, has permanent magnets.
Due to this, the magnetic field is constant, and (unrectified/unregulated AC) output voltage is totally dependant on the RPM. All the reg/rec can do is limit the voltage. So low RPM=low voltage, and high voltage (i.e. above 15 to 15.5V) is caused by a bad regulator or possibly poor ground connection.
You do not state what PMA setup you have, if it is built from used parts or other bikes, it could be that the magnets are weak or the rotor comes from a higher revving engine than your XS.
The 12.3 V you see at idle with battery connected is mostly irrelevant, as a good battery should have 12.6 volts with no load, even without the alternator running.
I also discovered a related issue when I installed a Powerdynamo PMA/CDI setup on my RD350. I used my (cheap) multimeter to check the charging voltage, and it read 17 volts or so. Obviously, this worried me a bit, so i asked an electrician buddy to bring his professional multimeter to check once more. Using his Fluke, all was fine, 14 to 14.5 V.
It may be that with PMA alternators, some transients or other phenomenon, make cheap multimeters show incorrect voltage values. So I suggest you try again with a better ("true RMS") multimeter, just to rule out the issue I found.

 

[jkocr2]

Thanks! It's the kit from mikesxs which appears to be the same as the xscharge kit. All measurements were taken with a professional fluke meter

Could be my idle is set to low but I set it with a mechanical tach hooked up. With the battery it seemed to only max out at 14.6v...also the 12.3v was from a not fully charged battery.

Could the capacitor just not be buffering the voltage enough? Should I try a different regulator...I have a spare I could steal from my buddies bike that's from a hughs kit.

Maybe I'm overthinking all of it and just need to bump my idle up..who knows

 

[Kathos]

I dont know about the PMA kit but usually on the stock system, overcharging comes from the regulator. It can be either the regulator itself, or the signal the the regulator is receiving.
In addition to the voltage the the capacitor(battery) is measuring, you should take a measurement of the maximum voltage at the regulator. If there is a voltage drop between these measurement, the regulator will not regulator properly causing either low voltage or high voltage.
On the stock charging system, (combine reg/rec) you can bypass the regulator by either supplying power or ground to the green wire. This will cause your bikes voltage to either spike over 15v or not charge at all.
If the input voltage to the regulator is the same voltage that the capacitor measures, and bypassing the regulator yields 15+ and no charging, then I would suspect the regulator itself.

 

[OakBehringer]

What's your idle set at? I'm running basically the same setup with the addition of an e-advance. Mine starts first kick as well with the headlight on and a neutral light and led taillight. It's the charging at idle I'm trying to figure out

So you saying my setup is fucked up is really no help...but thanks for the comment!

No, it definitely does help: it lets you know that your list of components is OK. You don't have to toy around with adding capacitors, etc.

I don't know what my idle is set at. I don't have a tach. I set it where it feels right. I upped it a little when I added the cap. I don't know if that was necessary, I've only been on two rides.

If you're worried your idle might be too low, turn that little screw and try setting it higher

The battery holds a charge a lot longer than a cap, so it may have masked the still existent problem. It sounds to me like you have a faulty reg/rec or a faulty cap. -OR- bad wiring somewhere in your system. 9v at idle is way too low.

 

[jkocr2]

I'm going to try a new regulator, I'll report back