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c0al67

bad battery, hoping not other issues

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c0al67
Battery died today, it had been sitting for about 3 weeks due to work. I jumped the bike and rode it for a short while, made it about a block before it died. The RPM's and Speedo were both off, reading about 68MPH and 8k RPM while I was just rolling along probably 35 mph in 3rd. I had the battery tested and it's bad, so I'm ordering a new one.. but i'm concerned about the speedo and tach. Could having a completely dead battery cause these issues??

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USMCFieldMP
The battery could certainly have caused those issues. You'll find out once you have a new one in there, won't you? ;)
 
I'd check what the bike is putting out while it's running, just to make sure the battery was the only issue.

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c0al67
I got the battery to hold a charge and just took it around the block again. Tach seemed okay but speedo is still reading wayy to high. :(

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c0al67
battery (off) reading 12.4v. Engine running (idle) reading 14.5v

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USMCFieldMP
The battery reading is a touch low, but not terrible. 12.0 and below, replace; 12.7 or less, recharge required; 12.8 and up, good to go.
 
I probably wouldn't worry about it until you replace the battery. You're essentially trying to diagnose an electrical problem when one of your sources of electricity is bad.
 
If you really want to though, you can try checking your speed sensor's connection.
 
nSkbrywg.jpg
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Guest Ralph
Check the speedo as not changed to KM instead of MPH
Thats if your market bikes can be changed.                              

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c0al67
Thanks for the post with the speed sensor info! After charging all night the battery is showing 11.8v so I think it's just dead. I'll check it out again once I get a new battery in there

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c0al67
update on this, new battery fixed the issue. So if you ever start to have weird electrical problems, the battery can certainly cause all kinds of strange things if it's nearing end of life. Even charged enough to start the bike and run, it was causing tach and speedo issues. It was putting out 12.4v at the time... so if you're battery isn't putting out 12.8 or better i'd say it could cause issues!
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gregjet
This info possible should be a sticky in trouble shooting. Great indicator that will show up early. If the speedo starts reading high check battery.

Go forth and modify my son...go forth and modify...

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Guest Ralph
When a battery starts to fail they can lose the ability to act as a
voltage stabiliser so you start to get peaks and troughs in the voltage
and that as well as low voltage that upsets the electronics,
if the system like most modern bikes is intended to run permanent head lights
using things like low wattage bulbs that remove this load can have the same effect.
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rick
Starting that big, high compression motor in my Aprilia is hard on batteries. Keep in mind, that when battery voltage is low, a starter motor will draw even more current.
 
Seen more than a couple of times guys posting up that the starter turns over kind of slow, the bike fires up, runs for a couple secs and then stalls. Weak batteries are frequently the cause. After the starter sucks the voltage way down, there's just not enough left to keep the ECU and everything it controls (fuel pump, injectors, coils (4 of em for 2 cyls) a ton of relays etc.) happy to allow the bike to keep running. What output there is from the charge system is sucked away/diluted by the battery.
 
I find this dash issue interesting as weak batteries have not only caused Futura dash panels to misbehave, but actually have resulted in some deaths. Would seem the electronics in the dash do not like being forced to run with low voltage.
 
Glad to hear it was revivable and not a failure.
 
None of this was ever a problem when speedos were cable driven and there was no ecu or FI. But clearly, this is not the case anymore. Everything electrical bit must be fit and healthy or bad stuff can happen. All my vehicles live on float chargers when not in use and have active volt/charge monitors running while in use
 
 
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rick
Like what Ralph posted above, the battery not only provides the current needed to turn the starter, it also acts like a great big capacitor - a nice smooth DC voltage pool if you will. The charge system is really designed to keep the battery happy - not to drive the electrics which are now as much sophisticated electronics.
 
You can try disconnecting the battery after the motor's been started. It's not an experiment I'm gonna do.
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Beemer
Like what Ralph posted above, the battery not only provides the current needed to turn the starter, it also acts like a great big capacitor - a nice smooth DC voltage pool if you will. The charge system is really designed to keep the battery happy - not to drive the electrics which are now as much sophisticated electronics.  
You can try disconnecting the battery after the motor's been started. It's not an experiment I'm gonna do.
I see, the magneto system just doesn't provide the power that other charging systems can so if the battery isn't charged enough electronics start to fail. I remember how on most of my older bikes you could bump start them with a bad battery and it would run fine, but then again they didn't have digital dashes.

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rick
They didn't have fuel injectors or fuel pumps or multiple relays supplying current to those things either.
 
Somewhere there's a wattage spec for this charging system - not really correct to call it a magneto. It's a 3 phase alternator that produces AC voltage that must be rectified to DC and ten regulated to 14-ish V - I'd guess the output is somewhere around 400 watts. 400/14V = 28 amps. Also dunno how much is used just to keep the bike running, but between headlight/running lights, tail lights and all the stuff needed for spark and fuel, it's probably up near 300 watts, if not more. The starter motor can easily draw 30-50A, so the battery has to be healthy - always.

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Guest Ralph
Do not under any circumstances disconnect the battery wile engine is running.

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Guest Ralph
When you press the starter even with a good battery I would not be surprised to see the battery
volts drop to about 10v that must be getting close to the point were the electronics give up,
not just the 07 stick a volt meter on anything with a leccy starter just how it is, putting
thicker starter and earth cables can help but to be honest why bother mine fired up just
as it always does after sitting in cold weather for about 6 weeks. You likely just got a
bad battery even Yuasa get it wrong now n then it's rare but they do and the 14.5v on
charge is ok so good to go.

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rick
ditto that
 
Like I said, not an experiment I'm ever gonna do.

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Beemer
They didn't have fuel injectors or fuel pumps or multiple relays supplying current to those things either.  
Somewhere there's a wattage spec for this charging system - not really correct to call it a magneto. It's a 3 phase alternator that produces AC voltage that must be rectified to DC and ten regulated to 14-ish V - I'd guess the output is somewhere around 400 watts. 400/14V = 28 amps. Also dunno how much is used just to keep the bike running, but between headlight/running lights, tail lights and all the stuff needed for spark and fuel, it's probably up near 300 watts, if not more. The starter motor can easily draw 30-50A, so the battery has to be healthy - always.
Gee, I didn't know that, I was just going by what the manual says, Charging system: AC Magneto. I'm going back to bed for a month.

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rick
They didn't have fuel injectors or fuel pumps or multiple relays supplying current to those things either.  
Somewhere there's a wattage spec for this charging system - not really correct to call it a magneto. It's a 3 phase alternator that produces AC voltage that must be rectified to DC and ten regulated to 14-ish V - I'd guess the output is somewhere around 400 watts. 400/14V = 28 amps. Also dunno how much is used just to keep the bike running, but between headlight/running lights, tail lights and all the stuff needed for spark and fuel, it's probably up near 300 watts, if not more. The starter motor can easily draw 30-50A, so the battery has to be healthy - always.
Gee, I didn't know that, I was just going by what the manual says, Charging system: AC Magneto. I'm going back to bed for a month.
Nomenclature and some funky translation from Japanese, lol. In that there are no slip rings, OK, why not. 
Be that as it may, the battery has to be healthy for every system on a modern bike to run properly 
 
 
 
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rick
Next they'll tell us it's a two stroke.  :-S
And that's what I associate magneto to. How a chainsaw/weed whacker makes a spark is much magic
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