86 Yamaha fx600 battery issues

[suppoz]

Hi All,

I have a friend that just purchased a bike.. he's having some problems with it (below). Can anyone provide any insight? The typical thought would be bad battery, or alt., but I wonder if it's anything more then that.

The person that sold the bike mentioned that this problem was ongoing with this particular years model. That doesn't seem right, and I couldn't locate any other document to back it up...

Thanks for your time everyone..




Hi, This is the problem that I am running into with my bike. I recently purchased a used 1986 Yamaha fz600. I’ve taken her out a few times now, and what happens is the battery gets drained and does not get recharged. It runs excellent mechanically while the battery is holding out, say 20 miles and 10 start-ups or so. Then it appears that the battery has died, the engine starts to sputter, and rolling on the throttle does nothing. The bike loses most of its power, and can’t accelerate. At this point it just coasts to a stop with the engine trying to turn over, and I roll to a stop where the bike’s power just cuts out. If I attempt to re-start it, the battery has no juice to turn over the engine, and it just clicks. I’ve been able to get it running by pushing it and popping the clutch, but this only starts the engine temporarily. It runs out of juice momentarily again.

I have been thinking that either the battery is bad, or the alternator is not recharging the battery. I don’t know what else could be draining the battery, or why it is not recharging while the engine is on.

Thanks so much.

[SSearchVT]

Take a look for the obvious blown fuse, or broken wire in the harness. After that it could be the regulator, and/or the the stator (alt). The regulator is usually a small box with fins on it, you might get lucky and find it right under the seat. Good Luck...

[RandyO]

More than likely the regulator/rectifier is the problem

RR's in most motercycles are destined to failure, by design, unlike a cage alternator most motorcycle regulators do not regulate the voltage by regulating the field strength in the alternator.

the Alternators have permenant magnets to the higher the rpm, the higher the voltage & power output. the RR regulates the voltage by shorting the excess back to ground. doing this creates heat ( the reason you see the big heat sink fins on the RR)

heat is not good for the semiconductors inside the RR, a computer fan mounted like you would to cool a computer chip helps get rid of the heat.

Often a RR will check out good when the bike is first started, then after it warms up, it won't work properly. sometimes a bad RR is hard to diagnose for this reason