Fellas,

I haven't been riding my '87 750 Paso in a while (2 yrs) , as I had developed an electrical problem and haven't had the opportunity to properly work on it until now. It's a shame, so I am trying to get it running as soon as possible, hopefully with your help. Simply put the battery isn't being charged sufficiently at idle (I have read the electrical upgrade).

Here are the details with the battery fully charged (~ 13V)

- Brand new battery

- Sometimes won't start with voltage less than 13V

- Current draw from battery with engine off, with various ignition positions:
Locked: 0 mA
Park: 1.2 A
Off: 0 mA
On: 4.8 A
Note: This seemed reasonable to me due to power consumption of lights (5-60W)

- Voltage across battery, with various ignition positions (particular instance):
Locked: 12.9 V (steady)
Park: 12.7 V (dropping @ ~ 0.01V/s)
Off: Same as Locked position
On: Plummets @ ~ 0.1 V/s
Note: On position seems excessive!!

- Voltage when running, at various RPM:
1K: Drops steadily from the On position voltage @~ 0.05 V/s
1.5K: Greater than 1K voltage, but less than 2K, and steady
2K: 13.8 V (steady)
2.5K: 13.8 V (steady)
Note: Performance at 1K clearly indicates the draining of my battery

- My wiring is a little scary, as there are loose leads that I am not sure are necessary or not, yet (used bike)...just being honest

- I've spent a decent amount of time cleaning grounds and contacts under the seat, but hadn't got to the electrics in the front of the bike, e.g. electrical panel, key ignition, etc.

Any clue what may be the fault? One idea I had, was possibly a short in the ignition wiring? I was also thinking about bumping up my idle ~200-500 RPM...I'm not sure if this would end up being the real fix, or a fix that would mask the real problem? Any ideas would be appreciated!

Thanks,

Michael

Michael,

You are on the right path by cleaning everything first. Your loads don't seem to be too high, so I don't think you have an excessive draw on the system. Clean the terminals to the voltage regulator and try to find the connections to the alternator and clean them too. This should all be under the seat and the alternator wiring is on the left (clutch LEVER) side of the frame. Make sure to clean every ground strap. anything that goes from the frame to the engine is really important. You may just need a voltage regulator, wouldn't be the first one to go bad! You voltage regulator looks to the wiring loom to see the current voltage and then adjusts itself to put out more or less. If the wiring is dirty, too small and a long way round (exactly how the Paso is wired BTW), then it won't charge properly.

If you read the wiring upgrade thread you know that the wiring is crap, particularly the way that the power is run; battery, fuse box, key switch, kills switch, horn, oil sender, coils. While trying to resolve my electric woes (generally starting problems) I worked in the dash area but found no resolution. That is what lead me to making the upgrade. I feel that you will find that all is well in your dash and that the wiring change will make things right.

Good luck!

While troubleshooting my past regulator, I fried it when my ammeter accidentally disconnected (alligator clips) and formed an open circuit. So, my regulator is practically new, along with my battery. Maybe it isn't get the proper feedback? That's where the conspicuously unconnected wires may be a factor I just need to dig into the electrical diagram a little more, although it isn't the easiest to follow (if you know what I mean).

I'm actually suprised to hear the voltage drop I am seeing with the engine off, is normal: it will suck the battery dry within a matter of 10-20 mins. Guess I'll just have to be quick on the draw (start button)...! I will also look into the wiring upgrade; although I didn't originally have this electrical problem, so I am hoping its correctable.

Thanks for the feedback. Any other suggestions will be well received.

Michael

The problem I have with my 88 Paso is with the turn-signals. Every time I engage the left turn-signal the bike starts to misfire and gets to cutting out!

Sounds like a short in the turn signal wiring. I think I'd rather have that problem, than a dead battery. At least you can always turn right three times.

By the way, a coworker suggested my problem may be the generator brushes...? I think I will also check it's ouput.

Michael

Doh!! Well, I will may check the alternator output, just to be thorough; as it is simple enough.

As for the battery I will have to check, all I know is it is 14Ah; but I can say the previous battery (died due to inactivity) was an Interstate (14Ah) and the bike had the same exact problem. I'll get more details this evening.

Thanks for linking to the wiring diagram!! It will definitely get some use.

Michael

this is in reference to the comment that there are no brushes in an alternator, while I have never had a paso alternator apart , I have had automobile alternators and aircraft alternators apart and they do have brushes, they just ride on a slip ring instead of a commutator like motors and generators. and they eventually wear out..

Folks,

Now that I am home, I realize the reason why I thought it may have been a generator...the Ducati manual says so (M10)!...although in the front (A10) it is referred to as an alternator. You have to love the consistency Johnnie - I will definitely keep the possibility of the alternator underperforming open, although it had passed the Haynes alternator test: 13.5-15.5V @ battery terminals @ 3000 RPM (13.9V)...I guess that is a good sign.

Well, I just downloaded the wiring diagram and it is a peice of art. Thanks again Jon!

The current battery is a MagnaPower CB14L-A2FP; it's all they had at my local auto store, and it appears to be working fine.

Here are a few extra observations I made during an extended repeat run of the engine, which may mean something to some of you:

- RPM at which the system seemed stable: 1,500 +/-100 RPM (voltage maintained at ~ 13-13.3 V across terminals)
- Lower RPM's lowered the terminal voltage to < 13V and seemed to be steadily dropping, and head lamp would dim

--- NEW OBSERVATIONS:
Over the years, I had forgotten that the engine tended to ?? pop in the cylinder area, and stumble; eventually leading to it dying. It may be a misfire?? It doesn't do this until the engine has warmed up for ~ 5-10 minutes at stand still, and is at idle. I found that it would, more or less, go away when I increased the RPM to 1,500 (also increasing the voltage at the terminals to ~13.3V) Does this mean anything to anyone?

Also, I noticed the "generator" light doesn't turn on at all. I'm not sure if this is related, or just a wiring glitch.

Well, I have my opinion on what the root problem/s are and possibly where to begin looking. I am also thinking the wiring upgrade may be a good idea, but I would like to solve the root problem first...then decide. At the same time, it is obvious I could use some help, and would appreciate your expertise, and advice. Have a good evening

Thanks,

Michael

Rocket man said " Over the years, I had forgotten that the engine tended to ?? pop in the cylinder area, and stumble; eventually leading to it dying. It may be a misfire?? It doesn't do this until the engine has warmed up for ~ 5-10 minutes at stand still, and is at idle. I found that it would, more or less, go away when I increased the RPM to 1,500 (also increasing the voltage at the terminals to ~13.3V) Does this mean anything to anyone? "

just a thought but this popping could be down to the carb if you have the dreaded weber fitted still.. my paso used to pop and missfire like yours until i ditched the weber carb and fitted a pair of mikunis no trouble with popping and it starts easy as well.. as for the charging problem sorry i know nothing about electrics

That could definitely have been a possibility, but it turns out I have Dellortos. Although they probably could use a rebuild one of these days, the popping appears to be inversely proportional to the RPM/Voltage. At idle, it is very frequent and results in the engine stalling. At 1,500 RPM/3.3V: nothing, it runs relatively smoothly. Hopefully that is one ailment I don't currently have.

Thanks for the help Dave.

Measure the voltage at the coils when running. It may be low enough to casue the engine to load up and then the weak spark doesn't fire.

What do you mean by load up? I will check the manual when I get home, but if you happened to know what a high or low voltage reading,that would be helpful. Also, I assume you are referring to voltage input. I'm learning as I go here...

Thanks for the direction.