Batt sign on Atari

I have the Battery sign come up on my XL 750 come up on my bike and I can't work out why , I have put multi meter on the battery and says charging at 13.5 volts can anybody maybe point me in a direction to look to see why this is happening. Also my RPM gauge is not working same thing anything I can look for to see why this is happening also. I haven't got a manual yet to look at a wiring diagram.
Any help would be appreciated.

 

Please forgive me, I am going to assume that you mean an XJ750 since it appears that a Yamaha XL750 is a jet ski. The XJ750 (at least an 82 Maxim) has a red and white wire that would normally be placed in an opening in your wet cell battery. If, like me, you are using an AGM, or other closed cell battery, you can bypass this sensor by splicing it in to something like your brake light that comes on with the bike with a 2.2k ohm resistor to trick the sensor in the computer. I actually did this very easily (and probably appallingly) by just twisting two of the 2.2k ohm resistors together and splicing the resistors inline with the red/white wire and just tucking the end into the male/female connector part where the taillight connects to the loom under the seat. It might be poor form, but here is a link to another site that makes the process very clear: http://www.xs11.com/forum/showthread.php?t=668 . This is very simple, and even a complete noob like me was able to pull it off. I thought I saw something on this site, but a quick search didn't come up with it.
Someone else will need to chime in about the tach, that is electronic and relies on some sort of sensor, I believe.

 

Originally the old batteries had a pick-up that threaded in to one cell on battery. Most new batteries are sealed units, there should be a wire ( check manual wiring diagram mine is red/white on my 82XJ750 Seca , I put two 2 ohm resisters wired in series to positive side of battery ( others wire it in to the tail light) . Mine goes out after engine start and when it goes through cycle.

 

I was posting but TheCrazyGnat beet me to it LOL

 

Sorry, didn't mean to steal your thunder!

 

haynes 650-750 free down load
http://www.manualslib.com/manual/837861/Yamaha-Xj750.html
or

http://www.pdfmotomanual.com/index.php?r=site/page&view=manuales&order=t&key=Y&make=1752&lang=ENG

 

The battery acid level sensor can be modified to act as a battery voltage sensor.
Do this:

The sensor wire is white with a red trace.
Connect to a 2 K Ohm (not 2 Ohm) resistor
Connect the resistor to a ring terminal.
Connect the ring terminal to the positive battery post.
You will now get a warning when the battery voltage drops to the point where restarting might not be able to occur.

 

Changing the battery light from an water level in the battery to a voltage indicator makes you aware if your charging system goes south so you have a chance at getting somewhere rather then ending up in the middle of nowhere with a dead battery. Plus one on this mod !

 

Listen to k-moe, that's what I do.

 

Thanks for your help gents I will do that and yes I must apologise it is a XJ 750

 

There's also this:

The HCP14180 Battery Sensor Bypass Kit

Save yourself the trouble of sourcing parts when it's been done for you.

 

When Radio Shack closed its doors here in my area, finding resistors and other small electronics locally is almost impossible. If you wanted to buy resistors for a project they had small packages of 5. I know they are cheap and the packaging probably costs more than the resistors did. Buying online now adds the shipping costs.
In any case getting the kit from xj4ever all shrink wraped and the proper connectors is very nice nice if you want to plug and play with a factory like fit and look. Not that it makes a huge difference but Len does a great job at making what he sells is of the best quality and provides information sheets that come along with.

 

Maxim or Seca? It wont' matter for this question, but it will for other questions that you may have in the future. Most of us place our bikes in our signatures.