I'm working on a 1991 Gs500 that I will be buying next month, and ran into an interesting problem tonight.  I used the battery from my car(yes, the car was not running), and after the carbs were filled with gas, it started right up.  Idle was normal(using the choke), and I fully warmed the bike up.  Once the bike was up to riding temp., I removed the cables, and it didn't want to rev. at all.   I hooked the cables back up, and it reved up great :dunno:.  This is a former drag bike(et class), and it running properly is part of the deal.  I'm just trying to make sure that there is no other problem than a bad battery.

Don
:mrgreen:

it's either a fried battery or a bad alternator....it's probobly the alternator because when you hook up the car battery it will give the GS enough power to rev, but when you remove that battery the alternator isn't making enough power to run the bike at high rpm...

check the power going from the alternator to the battery

sounds like the batt is a STONE.  yeah the bike has a problem with a completely dead batt...

Quote from: werase643sounds like the batt is a STONE.  yeah the bike has a problem with a completely dead batt...

could be but wouldn't a good alternator make enough power to run a GS at all rpm even if there was no battery at all?

I've dealt with similar problems in cars, and have found that a truely dead battery is nothing but a loss for the charging system.  I don't know that much about bikes(I just started REALLY riding in Dec.), and I am trying to cover my a$$ on this.  I plan on giving my Gs450 to my girlfriend for her bday next month, so the bike has to run right.

Thanks for the quick replies.  As soon as I get batteries for my meter(and the time to follow up), I will check the charging system for voltage.  

This bike has sat for over a year(I am swapping the tank as part of the deal, the old one is leaking), so any other advice is welcome.

Don
'83 Gs450LD
'91 Gs500e

A battery with a shorted out cell will pull voltage down in the system, unless there is a current source that can elevate voltage enough despite the current drain that would cause through the small resistance of the faulty battery.

A strong car battery might have enough punch for that, but I doubt that the remaining working cells in the bike battery would have taken that for long (strong charging current rushing through them; they would be boiling like crazy, might even blow.)

So my bet is on the alternator / voltage regulator as well.

"Strong car battey?", I use a lawn tractor battery in my car(about 125cca), it is cheaper and weighs less, I allways have cables in the car though.

I guess that when I get back to it next week, I'll take the battery out of my bike and see how things go.........................

Don