Generator testing output voltage

confusa · Post by **confusa** » Sun Sep 26, 2010 4:57 pm

My 860 GT turn signals have always barely worked. Unless I am revving the throttle a little, they will not blink. Lights on, forget it. My generator light used to be on all the time, and now for some reason it isn't on ever. Read a few posts and am somewhat confused as to if the light is supposed to be on or not?!
I tested voltage across the battery and am barely getting more than 12v at idle. Rev it, I may get 13v. What should I ideally be seeing here? Just seems like it is really weak and I am unsure what to do about it.

wdietz186 · Post by **wdietz186** » Tue Sep 28, 2010 5:17 pm

The light is supposed to stay on.It just tells you the ign. sw. is in the run position.On the Darmahs it is supposed to go out but they use a different setup.If you have an early 860 the alternator is the same as the 750, only 150watts and not really up to low speed running with the lights on. The battery,if not fully charged and in good condition will eventually go flat unless the revs are kept up.An upgraded rotor or a rotor from an ST2 will improve the output or the later 200watt alt. can be fitted if you can find one.

confusa · Post by **confusa** » Tue Sep 28, 2010 7:04 pm

wdietz186 wrote:The light is supposed to stay on.It just tells you the ign. sw. is in the run position.On the Darmahs it is supposed to go out but they use a different setup.If you have an early 860 the alternator is the same as the 750, only 150watts and not really up to low speed running with the lights on. The battery,if not fully charged and in good condition will eventually go flat unless the revs are kept up.An upgraded rotor or a rotor from an ST2 will improve the output or the later 200watt alt. can be fitted if you can find one.

Oh, I thought that light was supposed to tell you the generator was charging. If not, wonder why it went out?

I looked at the engine and mine would have indeed been one of the 150 watt ones which sucks. I got a box of parts with the bike and maybe the guy who had it previously was thinking of doing that upgrade. I have two parts that I am unsure if they are just spares or upgrades:
0755-46-409
0755-46-810

If neither of those are upgrades, what model of ST2 rotor do I need? I found the information for the swap for a 750, is it the same?
http://willyg.homelinux.org/Alternator/
http://www.webbikeworld.com/t2/ducati-alternator/

Steve Foster · Post by **Steve Foster** » Wed Sep 29, 2010 1:33 am

I got a box of parts with the bike and maybe the guy who had it previously was thinking of doing that upgrade. I have two parts that I am unsure if they are just spares or upgrades:
0755-46-409
0755-46-810

Both of those stator bits are listed in the 860 GT parts manual of March 1975 for the early engines with numbers up to 851683 so it looks like you've got 150W spares. The upgraded stator had part number 0759-46-409 and it was considerably wider than the 150W one (as was the upgraded rotor).

wdietz186 · Post by **wdietz186** » Wed Sep 29, 2010 10:18 am

Oh yeah,The light is probably burnt out which would be odd considering the sub par voltages involved!

confusa · Post by **confusa** » Mon Oct 04, 2010 9:52 am

This work on an 860 GT:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 0457141209

Seems to say it's for a roundcase so I wasn't sure.

wdietz186 · Post by **wdietz186** » Mon Oct 04, 2010 5:52 pm

It also says it fits the early square case 860.You may want to look around and see if you can find someone breaking a later model 860 or Darmah, those had 200w alts as standard.The difference is the width of the rotor and the coil assembly and they will bolt right into the 860 side cover. Try and get the rect./reg too you want the one with the finned alum. case.

Wags · Post by **Wags** » Fri Oct 08, 2010 8:55 pm

I had poor charging on my 860GT as well when I got it. Same low voltage.

On GT's the Red light is a Indicator only to say the ignition is on. It's not a charge. If not working blown globe, poor connection (lume etc) . Also it comes from the fuse box under the seat Violet coloured wire 3rd fuse in on the live side.

The indicator problem will more than likely be a poor earth fault! or flasher relay in the headlight.

I Purchased a new retifier from Guzzino's for $89 bucks all good. Comes with wiring diagram.

I'm sure Steve(Bevel Hevean) has them for sale as well.

Try the cheaper easy option before you change the Alternator!

Mine has 3 wires 150watt as well. This unit only needs 2 wires connected the 2 yellow ones and disconnect the red. After a long ride when it's parked up on the trickle charger it says it's fully charged. Didn't do that before I fitted the unit.

My bike also lives on Battery trickle charger when parked up.

http://guzzino.com/vore12vsiph.html