For the Electricians

I was out getting the bike registered for the street saturday and went on a little 10 mile highway blast afterward. The bike started sputtering just shy of my street. Tried bumping it to no avail. I've got a stubborn electrical issue. Bought battery brand new yesterday...fully charged @ 12.6v +-. Motor starts fine but volts drop slowly and steadily down into the 11's. This told me that the battery was not getting charge from the alternator as it should be up to 13-14v when running @ oper. temp.. Did the usual fuse check...ok. Checked wires and noticed a burned wire at the connector from the harness to the alternator leads. pulled connector, cut the wires back a bit and re-joined. Not sure if this issue goes further as I re-tested and volts were dropping again as it ran. Oddly enough, when I cut the motor and kept the meter on the battery the volts very slowly rose to around 12.5v. I'm lost on this one. Regul./Rectifier? Alternator brushes? If this thing were running like a total loss, why would the V's climb when I killed the motor?

I vote for a bad regulator/rectifier

with a few exceptions, unlike cars that have voltage regulators that regulate the field strength of the alternator, and only make the electricity that is in demand by the vehicle, most bikes have permenant magnet alternators, the faster the spin, the more electricity they make, the rr is a bunch of semiconductors, diodes etc.s that convert the electricity to DC and shunt the excess to ground and dissapate the emergy as heat, that's why you see a big heat sink on the RR, unfortunately the disadvantage of this simple lightweight charging system is that rr's end up frying themselves

+1 id try that first. you can test them if you have a diode tester

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Originally posted by Rye
Regul./Rectifier? Alternator brushes?

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No brushes, it's a permanent magnet. I would say reg/rec for sure. Get one soon before you fry ther battery. It should be compatible with a number of bikes, borrow one to check it out before you buy a new one.


derek

There's brushes and they have a wear limit. I'm just gonna grab the alternator off my 750. The alternator on my 9r motor was used on almost all zx7s in addition to some zx6's. Nice to have spares.

Just for those interested, Sears Die Hard batteries are rebadged GS batteries...so good quality...just FYI!

There are brushes on that alternator??? Wow, I'm amazed.

derek

Yeah. I have no patience to play around inside the alternator especially since they can be had fairly inexpensively on ebay. Fortunately the 9r is basically a stroked zx7 motor and they share a lot of the same parts. It's a 3 bolt job to swap it out with the 750.

BTW, where have you been...haven't talked in like 30 years!

I'm amazed there are brushes in your alternator. My '81 and '82 KZs use a permanent magnet rotor.

Another quick thing to check before you blow a lot of money on a regulator is the power coming directly from the stator before it is rectified. The shop manual will tell you which connectors to check and you should expect to see something around 50VAC from each of the three windings. You can also check the resistance of the windings to make sure they are still good.

It takes all of 10 minutes to check and on the off chance it is your problem it could save you from having to buy a regulator.

Shesa long in the tooth .
The TLS is to . Hard wire solder it & shrink wrap it ...
Best done in winter ...
Connections sux well i guess they get beat up ....