voltage regulator question

[Rickthejetman]

hey guys i recently picked up a 78 standard and i have a question about the voltage regulator. when i'm riding along the headlight brightens and dims drasticly like it has an old mechanical regulator, i'm more used to modern bikes but i have owned old bikes as well and everyone with a solid state regulator held a more constant voltage. is this common with the xs or is my regulator going out?

[TopCatGr58]

Hey Rick,

Due to the age/design of the XS's charging system, dimming and brightening of the headlight with changes in RPM is relatively normal, but it shouldn't change that much! Since you say you just acquired the bike, one of the first things we suggest for folks to do it to go throughout the bikes harness pulling every connector apart, inspecting, cleaning, applying dielectric grease and such to get good quality low resistance connections again. ALso, there are several ground points, not just the main battery negative to frame, but also behind the engine/starter to frame...flex wire ground strap, also several grounds that terminate at the REG/RECT housing under the gastank, etc.

The ALT is a brushless one, only develops about 20 amps at maximum, and barely generates 12 volts at idle and can actually discharge the battery if allowed to idle for very long! Would also get a multimeter and test your charging voltage at the battery.....at 2500+ rpm, should get up to 14.5 volts from barely 12 at idle!

But CLEAN the connections first, and you may find your headlight much brighter at idle, and therefore won't necessarily get much brighter with higher rpms since it will THEN be getting good voltage earlier and not being loss to corrosion and such that gets overcome with higher rpms. Don't forget the ALT plugs BEHIND the main fuseblock panel. Also if you have the OEM glass fuses, replacing the fuseblock with solid style fuses/holder will also go a long way in eliminating electrical gremlins!

Now, I have to go place another batch order for more fuseblocks, almost out of this recent batch! See tech tips, and Parts/Services for sale STICKY thread in the For Sale forum for details!

T.C.

[Rickthejetman]

thanks for the great advise. i'll go through the harness this weekend as i'm also having a no turn signal problem that i suspect is a bad ground.
on my 1000 mile trip home from picking the bike up in colorado i had a hell of a time with the fuse box, so i replaced it with a blade style one i got from the auto parts store.
i did notice some of the connectors are a little sketchy so i'll pull them all apart like you said.

[Rickthejetman]

another quick question.. what if the headlight was dimming and getting brighter at a steady rpm cruizing down the road? like you can deffinatley tell when the regulator is kicking on and off?

[fredintoon]

another quick question.. what if the headlight was dimming and getting brighter at a steady rpm cruizing down the road? like you can deffinatley tell when the regulator is kicking on and off?

Hi Rick,
most likely that's an intermittent wiring contact. The prime suspect is the fat plastic connector where the 3 white wires from the alternator plug into the main harness. That sucker has been known to melt.

[crazy steve]

For a guide to the XS electrical system, look here: http://www.xs11.com/forum/showthread.php?t=33254

[CaptonZap]

Which bike out of CO did you buy?

CZ

[Rickthejetman]

Which bike out of CO did you buy?

CZ

ummm.. its a 78 that my dad had since new. then he sold it to a buddy about 15yrs ago and bought it back about 5 yrs ago.

well i went through the bikes wiring today. cleaned all the connectors and grounds. i got the turn signals working again but i'm still having regultor issues. steady cruzing down the road the headlight goes bright and dim. very harsh voltage regulating. i expect the voltage to drop at idle but steady 4000rpm should be steady voltage right? or am i expecting to much from a 33yr old solid state regulator?

[TopCatGr58]

Hey Rick,

That does sound rather flaky. A fellow xsive makes a very strong replacement unit, much stronger than OEM, and gets the system charging at much lower rpms. You can see info in the For Sale Forum, STICKY THREAD regarding parts/services by Members, GEEZER is the fellow. The price is similar to a generic replacement, and much cheaper than an OEM replacement. I had one on my machine for the past couple years, but have removed it since I did my Automotive Alt mod, but I've got another machine I'm looking to rebuild, so I can't part with it!

There are diagnostics you can do to check the Regulator(See manual), but if it is working properly, it should hold a steady voltage at the 2500+ rpm range!

T.C.

[clcorbin]

If you are having regulator issues, Geezer's replacement is HIGHLY recommended by a lot of members here. Much better than stock, even new stock.