generator 51

[wrench184]

I am wiring up my 51 and if I connect the gen F terminal wire to the light switch my headlight comes on.If I hook it to the ingnition terminal when I shut the ignition off the bike keeps running.What am I doing wrong?Can't seem to get the gen wired correctly.everything else ok!

[john HD]

sounds like there is an error in the wiring at the switch.

-or- the terminal/contact plate on the back of the switch is in backwards.

what did you use for a wiring diagram?

john

[steve_wood]

Wrench184:

You mentioned the "F terminal". Is your generator original and correct for 1951? I thought that the two-brush generators with "F" and "A" terminals were for much later models.

For example, the 1965 12 volt generator has an "F" and an "A" terminal. The F terminal is supposed to connect to a voltage regulator (not a relay). The A terminal connects to the master switch in the dashboard.

What type of generator do you have and exactly how are the terminals labeled?

[wrench184]

Thanks Steve,I would say that the gen is probably been changed.This is the way I got the bike.It is a 6volt system and the front terminal is stamped F and the rear is stamped A.Wiring it to the specs in my pan book which is a clymer doesn't work.Anything you can tell me will be a great help?Thanks

Don

[steve_wood]

Look on the generator body near the terminals. Does it say 65-12V ?

[wrench184]

Sorry,stamped on the gen is Harley Davidson under that is made in USA and under there is model 56 thats all I can see other that the F terminal an
A terminal

Don

[hogboy52]

The '51 wiring diagram is for a three brush generator. It won't work. Use the later two brush gen. with regulater wiring diagram.

[Frankenstein]

wrench184, sounds like a mix and match electrical system, and that's causing the problem. First, are you using a relay on the output of the generator? Sounds like you are.
If you have a voltmeter, try this: start bike, let run at fast idle, and see what voltage you have at the A terminal. Then GROUND the A terminal briefly to see if the voltage goes up at all. If it does, probably all you need to do is get a 6 volt regulator and connect it to your generator in the normal manner. You won't need the relay at all.
I suspect your generator is not putting out any juice until you hook it to the light switch, then the fields inside the generator are being grounded through the headlight, causing the headlight to light and also making the generator to make some output. When you hook it up to the ignition terminal, nothing happens until you shut off the switch, then the field grounds through the coil, causing the generator to again make electricity and keep the engine running.
By the way, all the regulator in a 2 brush system does is control the field terminal's connection to ground to create, then regulate the output of the genny.
Just a guess, but give it a try and see what gives.
DD

[awander]

Then GROUND the A terminal briefly to see if the voltage goes up

Please don;t ground teh A Terminal!

Try the same procedure, but ground the F terminal.

[Frankenstein]

Awander!! Thanks so much for catching that typo! Reread it twice and still missed it
Dumb DD.

[wrench184]

I do have a 6 volt regulator already.I have eliminated the extra wire going to the ingnition switch and she is putting 6.25 volts back in the battery running around 1100rpm.The problem I have now is the gen light.I have tried a jumper wire from the gen term and the field term on the reg to the light on the dash and the light doesn't work like it should.I can't figure out whats up!any of you guys got any suggestions for me?Thanks again!

Frustrated

[steve_wood]

Wrench184:

Try this: Disconnect all wires coming from the gen or regulator that connect to the gen light. Turn the switch on. Is the light still on? If it is, you have a short somewhere that is grounding the gen light so it will always be on.

If the the light goes out, the problem lies with the wiring or gen.

Where did you measure 6.25 V? Was it at the output of the regulator (i.e. the "Bat" terminal) or straight off the gen (i.e. the "A" terminal of the gen or the "Gen" terminal of the regulator)? Try a connection from the "A" terminal to the wire from the gen light that is NOT connected to the battery.

Normally, the gen light is supposed to be powered on one side by the battery and on the other side by the "A" terminal of the gen. Having roughly the same voltage (6V) on either side of the light means no current and hence the light goes off.

[wrench184]

Steve,I wired the gen light up the way you suggested and I beleive I am going to have light now,once I get the bike to start for me again.I have ran into a whole lot of bugs in this one.Seems like she starts when she wants to.Thanks for all of the help!I am sure am going to run into more problems.

Don

[steve_wood]

Don:

So does that mean the generator light is coming on when you turn on the switch?

Steve

[wrench184]

Steve,Yes the light comes on as soon as I turn on the ingnition.got her started and the light went right out.I have a little fuel problem I am going to take care of and I will be able to run it down the rode for the first ride.I'm not going to get to far from the shop the first ride though.Thanks again!

Don