Questions about voltage regulator, elec start, and headlight

[cpolaris502]

My 1974 400 is finally running awesome after some engine and carburetor work. My next task is the head light.

I blew the first headlight pretty quick, same with the tail light. It has electric start with a battery installed but the battery is completely shot.

Checking voltages at the head light, it is 12vc AC at idle and gets up to about 18v AC at higher rpm. I have been reading and saw people talking about everything being DC on an electric start sled because it has a rectifier. I have tested the AC and DC side of the rectifier and each on reads the same voltage, one in ac and the other DC so I assume this is working fine. I tried two different voltage regulators also, one oem off a parts sled and one brand new. No change in the voltage at the headlight.

Ground is good at the regulator. (.6ohms to ground)

My questions are: Do I need to have a battery installed, or a good battery for everything to work properly? I have disconnected the battery with no change also. What else could I look at to find the problem with this? The same voltage is going into the regulator wire.

[JDT]

Try to get a better ground. Sand the rust/oxidation off the frame where the regulator mounts and also teh ground wires.

You do not need to have a battery installed for the system to work properly but a bad battery can pull the voltage down.
Your problem is just the opposite, voltage to high.

If your meter reads the same voltage set on AC or DC than your meter is bad.

[harleysportster]

My 1974 400 is finally running awesome after some engine and carburetor work. My next task is the head light.

I blew the first headlight pretty quick, same with the tail light. It has electric start with a battery installed but the battery is completely shot.

Checking voltages at the head light, it is 12vc AC at idle and gets up to about 18v AC at higher rpm. I have been reading and saw people talking about everything being DC on an electric start sled because it has a rectifier. I have tested the AC and DC side of the rectifier and each on reads the same voltage, one in ac and the other DC so I assume this is working fine. I tried two different voltage regulators also, one oem off a parts sled and one brand new. No change in the voltage at the headlight.

Ground is good at the regulator. (.6ohms to ground)

My questions are: Do I need to have a battery installed, or a good battery for everything to work properly? I have disconnected the battery with no change also. What else could I look at to find the problem with this? The same voltage is going into the regulator wire.

Just to clarify, The lighting is still energized by AC voltage even when the sled is set-up with Electric Start. The battery is the only thing recieving DC voltage. I am with Tod, check all the connectors. Also, if you have a good battery hooked up, it may balance out the voltage, bringing it back down to 12 to 15V. The AC volts will always be higher without a load on it.

[400brian]

Pat

I disagree, I believe everything runs DC with e-start. To make the tach work, you must tap into the lighting coil wire before it gets to the rectifier. Also, with e-start, you can turn the lights on without the engine running. So I think it pretty much converts the sled to DC.

I thought to run without a battery again, you had to unplug the e-start connector, and re-insert the jumper wire you removed when you plugged it in. I don't think the book is really clear about running without a battery, but I'm not sure its a good idea.

I burnt up a lighting coil dinking around like this.

[JDT]

Well we are both right.

Some sleds will power the lights from the battery without the engine running. Others will not, even with an electric start system installed.
It all depends on how the wiring is configured.

The plug that is removed on the midmounts when an e-start system is installed is not needed due to the conections that are made in the new plug that comes with the e-start option.
But the system will still work without actually having the battery as long as the harness is there.

I still believe that there is a problem with the meter as it should not read the same in AC and DC settings.
An typical example would be a reading 14 VDC and 1.2 VAC. What your are reading on AC is actually DC ripple.

And a reading of 0.6 ohms is not a good ground. Can you Zero your ohm meter?

Tachs require AC yes. What are actually reading are frequency not voltage.

[cpolaris502]

I think I have the plug with the jumper on it lying around somewhere, I could try unplugging the elec start one in the sled and just puttinmg the jumper plug on there to bypass all of the elec start stuff.

I think you misread about it reading the same on AC and DC. I am talking about the rectifier, I have AC going in and DC coming out and they are both the same amount so it is converting the signal.

From what I've read on other sites, anything under 1ohm should be a good enough ground. The .6 is measuring from the ground wire at the regulator down to the tunnel next to the seat where the paint is worn off. I think my next step though is to make sure that my ground is the best it can be and try the jumper connector and bypass all the electric start circuits.

[harleysportster]

Pat

I disagree, I believe everything runs DC with e-start. To make the tach work, you must tap into the lighting coil wire before it gets to the rectifier. Also, with e-start, you can turn the lights on without the engine running. So I think it pretty much converts the sled to DC.

I thought to run without a battery again, you had to unplug the e-start connector, and re-insert the jumper wire you removed when you plugged it in. I don't think the book is really clear about running without a battery, but I'm not sure its a good idea.

I burnt up a lighting coil dinking around like this.

Brian,
I stand corrected..After reviewing the wiring diagram, I see you point. It seems all the early JD sleds with E-Start using the "full-wave" rectifier had DC current to the lights. If you remove the E-Start wiring and replace it with the factory jumper, then it changes to AC current.
From '76 on, the rectifier was changed to a "single-diode" type and the lighting current remained AC, even with E-Start.

[JD600]

I think I have the plug with the jumper on it lying around somewhere, I could try unplugging the elec start one in the sled and just puttinmg the jumper plug on there to bypass all of the elec start stuff.

If you do this, just be careful to make sure you have the correct plug. They changed the placement of one of the wires and they are NOT interchangable. I learned this the hard way on my 800. I fought a no lights issue for months and i actually ended up installing an NOS wiring harness because everything else had been eliminated. Turns out, the delete plug i was using was from a 73. Just something to be mindful of.

DE

[JDT]

Good point Dustin.

Wiring harness's changed a few times over the years. They look the same but it only takes one connection to be different and the head scratching begains.

[Don O]

Which wire go where on the head light bulb? I have two 76 Cyclones and they are not wired the same. Pink and green are reversed. I thought the ground would be the center post but thats not the way it is either. Both lights worked until recently, the 440 burned out. That is the one I installed electric start on. Voltages seem to check out OK. Not sure at high rpm's.
It helps to have two sleds alike, check one against the other but, if they are both previously cobbled up it takes more reseach !


Don

[harleysportster]

Which wire go where on the head light bulb? I have two 76 Cyclones and they are not wired the same. Pink and green are reversed. I thought the ground would be the center post but thats not the way it is either. Both lights worked until recently, the 440 burned out. That is the one I installed electric start on. Voltages seem to check out OK. Not sure at high rpm's.
It helps to have two sleds alike, check one against the other but, if they are both previously cobbled up it takes more reseach !


Don

Don, here is a sketch.

[Don O]

this is looking at the end that goes on the bulb?

Thank You
Don

[skoalmint]

Dustin I tried to tell you there wasnt nothing wrong with your harness! I tested every wire. But it is just like your saying states in order to be old and wise ,you must first be young and stupid.That might posibly be the most accurate saying i have ever heard!Where did you get that from anyways,I know it wasnt from me, even though i have came up with a few LOL! But the main thing is you figured it out , so it was money well spent.Heck that harness looks alot better than your old one.Hell here is the worst part i like to think i am getting old and wise,But sometimes i think im still young and stupid.After all i live in Ohio and i have 30something Deere sleds,And guess what no SNOW!!!!!!!!! But i keep right on working on them like there is going to be another blizzard of 78-79 this friday.I have lost my mind!!!!!!!!!!!!!!!!!!!!!!Brock

[harleysportster]

this is looking at the end that goes on the bulb?

Thank You
Don

Don,
The wiring diagram is looking at the back of the bulb.

[cpolaris502]

I installed a brand new regulator, even ran a ground wire from the mounting bolt right to the engine ground. Still no change. I gave up for now, I'm only going to ride in the day time!