Best headlight/ taillight bulb

I have a 1980 XS Pamco/ PMA swap and was curious what everybody is running as far as bulb type and proper headlight/ taillight bulb wattage on their bikes? Also Is it true by running a slightly higher wattage bulb it will “ use up” some of the extra juice my pma is possibly putting out? I have no exta acceriories on my bike simply headlight hi/ low, turn signals, horn, volt gauge which should be in this week and of course the bike is kick only. Any further information is greatly appreciated. Thanks!

I don't have an answer for ya Alex. I do know that the PMA's are "constant current" systems and the output has to be dissipated somewhere...
Just thought I'd comment and bump this back to the front page so maybe you'll get an answer or two...

Thanks for bringing back up JimD54 I find your postings to be really useful. The voltmeter will be tested tomorrow hopefully im not going past 14.5 volts around 3000 rpm from what I’ve read. I’ve only put 40 miles or so so far on my bike since doing the PMA/ Pamco and the bike has been running great! I figured the voltmeter will give me some assurance on longer trips on how the electrical system is operating.

As mentioned PMA's put out the max current all the time. The reg/rec controls the extra current but shunting through a resistor. This causes heat. Excess heat tends to burn things up. A higher wattage headlight and tail light help use some of this current so not so much goes through the reg/rec. Less current through the reg/rec=less heat.
Most headlights that use an H4 bulb are a good option. H4 bulbs can be gotten from around 55/60 up to 100/110 or even more.
The stock tail light bulb is an 1157, 8/27 watts.
I would use something of that sort. LED lights have lower draw which is an advantage for the stock charging system but not so much for PMA's.
Leo

As mentioned PMA's put out the max current all the time. The reg/rec controls the extra current but shunting through a resistor. This causes heat. Excess heat tends to burn things up. A higher wattage headlight and tail light help use some of this current so not so much goes through the reg/rec. Less current through the reg/rec=less heat.
Most headlights that use an H4 bulb are a good option. H4 bulbs can be gotten from around 55/60 up to 100/110 or even more.
The stock tail light bulb is an 1157, 8/27 watts.
I would use something of that sort. LED lights have lower draw which is an advantage for the stock charging system but not so much for PMA's.
Leo

Hi. On this subject. PMA’s have been used on many British bikes since the late 50’s. Their solution to the constant production of power have been manyfold, including a switch to switch out some of the coils during daytime when all the output isn’t required, and the use of Zenner diodes, to bleed off as heat,excess voltage.
Bearing in mind modern PMA’s produce maximum output all the time at normal engine revs, the fitment of normal Halogen headlight and other bulbs is I would say essential. This situation will get rid of most, if not all excess voltage and have the added benefit of reducing the load on the battery and reg/rec.
As there isn’t a warning light or other form of voltage warning on XS twins, under voltage and overvoltage need to be monitored I fitted a cheap digital voltmeter, for my own benefit really.

Thanks for the info guys. When I cut my switch on and flip the toggle for my voltmeter It reads 11v before started. After running It stays at a constant 13v from idle or 3k rpm or more. It’s a new Kuryakyn meter wired directly to the battery. The battery is a year old. Currently running a 12V23/8w drag specialities bulb in taillight and H4 55/60 headlight bulb. No LED’s on bike. I understand anything over 14.5 volts is destructive but is this something I should worry about as far as a constant 13 volts when running? Other than that the bike runs / starts great. Any info would be great

The idea is roughly right, but there's no resistor. On a three-phase stator the RR on a shunt system diverts the unused power back down through the windings.
This leads to the stator suffering a double whammy - it's on full demand all the time, and the excess power is dumped back into it. Result - too bleedin' much heat. Frankly, it's surprising the windings put up with it for as long as they do.
Shunt RRs were a sort of solution to a problem, that worked well enough for long enough. Long enough for the bikes to be out of warranty and the second or third owner was left to pick up the repair bills.
Nowadays, the advent of the series regulator has changed the game - the charging circuit is simply cut, only what's needed by the demand (load) side is supplied and there's no excess to be dumped. The idea of a series regulator certainly isn't new - but thirty years ago the electronics to do it reliably or cheaply simply didn't exist.
Zener diodes were another approach to the problem, but were also horribly unreliable.

What do you mean by “series regulator” and where can one be purchased Grimly? Thanks for the great info!

Alex Wagers said:

What do you mean by “series regulator” and where can one be purchased Grimly? Thanks for the great info!

Click to expand...

To save me quoting lots of stuff, here's a very good summation of the state of our knowledge of it for now.

https://www.thegsresources.com/_forum/showthread.php?191795-GS-Stator

It was thanks to Jim (posplayer) that I was put on to the series RR and came to an understanding of the deficiencies of the shunt type. I'd known how bad the shunt was, and I'd tried to do something about it, same as any other GS owner over the years, but recent times have brought new products that solve the problem once and for all. Anyone here thinking of using a PMA should be aware of the pitfalls of them. They work, but they're not perfect, and to make them much more reliable the series RR is recommended.
The whole point is, these series regs have been around for a few years now and they can be found used from Polaris ATVs (beware of Chinese copies though), and one of the newer Suzukis is using an uprated version, but they're still expensive.
The other source of new ones is Compufire, and there are a couple of others.