[mattyo]

I have a question regarding my friend's (Ben) bike just because I'm a little confused and want to learn what's going on with this particular problem. So Ben's bike would basically not accelerate at high RPMs. We thought the carb jets needed cleaning and maybe they still do but let me finish the story on the bike first. So at high RPMs the bike isn't really choking or sputtering, it just doesn't accelerate like it used to. This weekend he took a 4-5 hour road-trip and the bike just died after a few hours while driving and then wouldn't start. He knew the battery was bad and replaced it and now according to Ben it seems to be running "fine" (whatever that means). My initial thought was that the stator or regulator is going bad, my reasoning being that presumably the bike isn't providing enough power of its own to make a good spark hence the reason it died while running. But I was thinking more about it and maybe if the battery is dead it begins to act like a short, thereby draining most of the power being generated by the bike? I guess I'm not entirely sure how batteries behave electrically when they die. Also once the bike is running you should be able to pull out the battery and the bike should keep running on its own power right?

 

[Nehalem Dave]

I vote partially plugged tank inlet screen, fuel filter or failing fuel pump. My assumption is that it does the same at X rpms in lower gears.

Jez my $0.02

 

[mattyo]

I vote partially plugged tank inlet screen, fuel filter or failing fuel pump. My assumption is that it does the same at X rpms in lower gears.

Jez my $0.02

It does behave similarly in all gears at X rpms, but I'm confused why a new battery would seem to fix this problem.

 

[tubes_rock]

DO NOT pull the battery with the bike running!

Let me repeat that for emphasis:

DO NOT pull the battery with the bike running!

The voltage regulator uses the battery to maintain its voltage regulation. If you pull the battery, the regulator has no reference, so it just sends along whatever the stator can throw out. At high RPMs, that's over 100 volts. That will destroy your ignition system, lighting and just about everything else on the wiring harness.

You can bring a battery to a car parts store and they can load test it for you. (usually for free!)

--Justin

 

["Captain D"]

<<<< Also once the bike is running you should be able to pull out the battery and the bike should keep running on its own power right? >>>>>>>>>>>>>>>>>>>>>>>>

DON`T DO THAT!!!
Old ignition and charging systems with mechanical points ~ That was OK to do that...
BUT with electronic igntions and charging systems you`ll burn up something!!!
They NEED 12V constantly ~ according to the Alternater/carburater and igniton professional I use...
Look at useful links in the stickies fer electrosport charging system diagnosis information...
Get you a meter and check the system the correct way...
My $.02,
Dennis
Sturgis2011

 

["Captain D"]

HA!!!
You posted as I was typing...

 

[mattyo]

Dually noted! I will not disconnect my battery while running.

So if the battery is dead but still connected, the voltage regulator has a very low reference voltage and doesn't feedback the full 12V to the battery?

 

["Captain D"]

So if the battery is dead but still connected, the voltage regulator has a very low reference voltage and doesn't feedback the full 12V to the battery? >>>>>>>
My guess is that it`ll put MAXIMUM amps to the dead battery in an attempt to charge it...

 

[verdeva]

mattyo - yes a battery can act as a short and take all of the stator power. So it is possible that the new battery has fixed this problem.

That said, I would want to check the charging system. Start with a voltmeter on the battery terminals; let us know what the voltage is when the: engine is off, engine is idling, and when the engine is rev'ed. It would be a good idea to look at the yellow wire stator connector to see if it is blackened or melted.

 

[Lukeg]

I might be wrong but when running you should se about 14v at the bat.

 

[mattyo]

So if the battery is dead but still connected, the voltage regulator has a very low reference voltage and doesn't feedback the full 12V to the battery? >>>>>>>
My guess is that it`ll put MAXIMUM amps to the dead battery in an attempt to charge it...

So does that imply the current normally going to the spark units and ignition coils is going to be severely drawn away to charging the dead battery? I'm confused because when my battery was dead I could jump start my bike and once running, it still had great acceleration and power in all gears, implying in my mind at least that all the ignition electronics were still working fine and drawing power off the stator/regulator. My friends bike however is acting like it's not getting power off the stator/regulator with the dead battery and the ignition electronics are not getting the power they need. I'm just trying to learn what might be different about these two cases. Also my friend's bike is a Ya**ha but I think the electronics should be similar.

 

[93gc40]

Yesw. if you have a dead battery it will drawn curent away from the rest of the system. Think of electricity as water flowing through pipes, pipes are the wires. The electricity will go via the path of least resistance. The battery is a BIG reservior in the middle of that pipe run, and it must be filled before the rest of the items can get electricity.

 

["Captain D"]

AND the battery must be FULL in order to send the MAXimum flow to the other areas, too...

 

[mattyo]

Yesw. if you have a dead battery it will drawn curent away from the rest of the system. Think of electricity as water flowing through pipes, pipes are the wires. The electricity will go via the path of least resistance. The battery is a BIG reservior in the middle of that pipe run, and it must be filled before the rest of the items can get electricity.

That's why I'm confused. Why would my bike still run fine with a jump started dead battery? I guess there are different degrees to what "dead" means but that is another confusing aspect of these two cases. My battery was too dead to even start my bike, but once jumped and running, ran fine. My friends battery could still (just barely) start the bike but then while running showed signs of lacking current to the ignition system and eventually died on the highway. That's what made me think his stator or regulator was possibly going bad as well as the battery starting to die. There must be some other hidden variables as to why these two stories of a dead battery seem to behave very differently.

 

[Nehalem Dave]

You are beating a dead horse. Do the battery diagnostics first per prior posts and go thru the troubleshooting process logically with a meter. An internally shorted battery screws everything up in your charging system and eliminating that is step one.

 

[mattyo]

You are beating a dead horse. Do the battery diagnostics first per prior posts and go thru the troubleshooting process logically with a meter. An internally shorted battery screws everything up in your charging system and eliminating that is step one.

Understood, I just wanted to do a little digging for some background info first.

 

[ttexastim]

That's why I'm confused. Why would my bike still run fine with a jump started dead battery? I guess there are different degrees to what "dead" means but that is another confusing aspect of these two cases. My battery was too dead to even start my bike, but once jumped and running, ran fine. My friends battery could still (just barely) start the bike but then while running showed signs of lacking current to the ignition system and eventually died on the highway. That's what made me think his stator or regulator was possibly going bad as well as the battery starting to die. There must be some other hidden variables as to why these two stories of a dead battery seem to behave very differently.

Your bike will NOT run fine with a completely dead battery. Just 2 days ago, I was an idiot and left the bike turned on ... ALL DAY. Went out to a completely dead bike. Had a good samaritan give me a jump. His jumper cables were on my bike for 1 minute or so. I started the bike just fine, and she seemed to be perfect. So I started to ride. After a few minutes, the bike started acting like it was out of gas, lots of popping and misfires. I pulled in the clutch, and it returned to a purr at idle. I tried to accelerate again, and same thing, pull in the clutch, and purrrrrrr.

The bike would idle fine, but did not have enough power to provide spark at any RPM's higher than idle (even the choke on was making it misfire). I ended up putting over to a tractor supply, and I let the bike idle for 20 minutes while I browsed around inside the store. After that, I was able to run home on it and throw the battery on a charger.

To summarize:

1. if the battery is dead, almost all charge will be drawn into the battery
2. the bike needs a voltage on the battery to generate enough power to run the ignition system
3. Don't be an idiot and leave your bike turned on all day.

 

[mattyo]

ttexastim
That was a very valuable story because that describes pretty well how my friend's bike was acting. It leads me to believe that my battery wasn't as dead as I thought but maybe just had a weak connection to the starter. Do chargeable batteries always fail in such a way to act like a short circuit while trying to charge? I guess I've always assumed that when a battery fails it would act like an open circuit. I guess I shouldn't have assumed that. I guess I also assumed that the stator/regulator circuit was smart enough to charge the battery with surplus current not being drawn by the electrical systems of the bike. Shouldn't have assumed that either.

 

["Captain D"]

I once had a bad rectifier/regulator ~
The Bike wouldn`t crank one night, I was able to push start the bike and make it home, 10 miles...
Figured the four years old battery was shot, so I bought a new battery ~ unbeknowingst to me that the regulator was bad...
The Bike ran good fer two trips to town during the week...
On the weekend, I trailered the Bike to the mountains of SC/NC area and rode the Blue Ridge range...THe ONLY time I had trailered it...
The Bike started and ran good a few hours, until the battery went "dead" then it wouldn`t crank, I was able to push start it...
Then it started running rough, "misfiring and cutting out"...I did get back to "homebase"...
I knew I had a charging problem then!!!
I bought a charger, and charged the battery overnight...
Then I could ride a few hours, until the battery went "dead" again...
I did this process of charge/ride, over the extended weekend and enjoyed riding the mountain roads...
When I got home, I pulled up this site and received the same expert help we`re giving you...
AND with the electrosport diagnosis chart I was able to determine the R/R was bad, replaced it and ain`t had NO MORE trouble to date...
I`m a TV technician by trade, I don`t try to figure WHY something broke or HOW, I just diagnose and repair it...
Good Luck,
Dennis
Sturgis2011

 

[mattyo]

Captain D
That was also a great story. Between you and "ttexastim" that was more what I was looking for out of this thread. I know I can whip out my multimeter and test the stator and test the regulator and test the battery but I'm also interested in how the bike physically behaves when either the battery dies or the regulator dies. Sometimes that information helps you diagnose, sometimes it doesn't but that's why I opened this thread, because I didn't know. And I learned some valuable things in the process. I didn't know a battery acts like a short circuit when it fails and I didn't know the regulator wasn't smart enough to keep enough current going to the ignition system when the battery dies. Also didn't know the battery provides a voltage reference for the regulator.

Thanks for everyone's comments, suggestions, experiences!