was riding yesterday, and all of a suden bike dies, no sputtering or anything, i just got gas. tried starting, wouldnt start, sounded like the battery was low. got home and checked voltage. bat was 11.6 (about 0%) threw it on the charger. itz back up to 100%. what would cause a battery to just lose charge like that. itz about 8 months old. i was thinking either the batt is defective or itz not charging while itz on the bike. any other reasons, and if so how can i check if itz charging while the bike is running. thanks in advance folks

 

Got a voltmeter?

Hook it onto your battery when it's charged and in the bike.

Turn your killswitch to "off" (motor wont run) now hit the start button and let it crank over for a couple seconds.

Now watch the voltage, it will drain down to 6-8v while crankingand when you stop cranking it shouldspring back up in voltage -that means your battery is good. But if the voltage doesn'tgo back up thebattery is hooped.

If the battery is good, move on to the next step:

Turn your killswitch to "on" (motor can run) and hook your battery up to a jumper. Fire up the bike and remove the jumper, then put the voltmeter back on and watch your voltage. If the voltage steadily falls, your rectifier is not letter the bike charge your battery, which will cause the engine to die because it's not getting enough voltage to keep it running.

If that's the case, inspect the wire harness attached to your rectifier. The rectifier is the small black box with heat dispursement fins on the right side of the tail frame.

Check to see that all of the wires are connected and none are shorting out. (you may want to wiggle the wires around with the bike running and the voltmeter on, see if the voltage starts to rise while you're playing with the wires and that will narrow down your problem to the wires)

If it's not the wires, it could just be that your regulator/rectifier is garbage (common problem for the F series)

Hope this helps!

 

To add a little to what was just written, measure voltage with a decent meter and also check it through the rpms up to 5k rpm I believe. The voltage should not get to 15 volts, but should be avbove 14v. (There is a test procedure in the service manual.)

 

thanks for the advice hersh and mike. i did as hersh said and the battery went back up after dry crank.started running it and it was ata steady 12.6. ran it for about 10 min and it was down to about 12.5 or so, rode around close by for about 20 min, and it died, checked batt, it was at 11.5 at that stage it wont start unless i let sit for voltage to rise back up into atleast the 12's. checked the r/r externals look ok. i havent looked into the manula yet, but could a burnt coil in the stator have anything to do with this? if so what esle can i check, or better yet, is there a more effecient way to check if the r/r is working properly?

 

What you need to do is check the voltage as the bike is running and get it gas. The voltage output should go up. When you say it was at 12.6, was that at idle, or at some higher RPM? If it was at a higher RPM than idle, you have a bad R/R I think. The voltage should be higher than that to charge the battery and run the bike.

 

12.6 at idle, when i reved, it went down instead of going up. it would drop down whilst i was reving and start to climb back up when i let go of throtle

 

Something wrong with either the Stator, wiring, or RR for sure. Battery voltage should go up when bike is revved as the RR should be supplying 14v to the system, which includes the battery terminals. My guess is the RR, which is the cheapest method assuming the wires look good.