Do your lights die at idle?

I've been working on a friend's 04 FE650 for the past 3 days. When he bought the bike the button wouldn't start it because it seemed to not spin it fast enough, he could only kick it. I suspected decomp issues, so we tore it down and I adjusted the exhaust valves and cleaned up some cruddy wiring behind the headlight, along with a lot of other unrelated service. We got it back together and found that the bike kicks over much easier, but the battery pulls down extremely fast, as if it's not charging.

I also checked my wiring work. The previous owner had put HID lights on and had run a dedicated lead straight from the battery for the HID lights, leaving the hot lead from the reg/rec unused. When I rewired it, I wired in the hot lead from the reg/rec for the lights so the battery wouldn't die if the lights were left on with the bike off, and taped off the hot battery lead for possible later accessory use. Now I noticed when the bike was running that at idle the lights would totally die, but would light when revved. I've seen peaky power on other bikes, but on all the light would be at least dim at idle.

I didn't get a chance to run any electrical tests before he took the bike yesterday other than testing voltage across the battery while running. I found it to show almost no voltage there. Obviously I can't make a definitive judgment without more tests and checks, but a sure bet is that the battery is not charging.

A couple of questions, the first being dumb...

a) The bike uses an alternator to produce power, with one of the fields providing ignition power. If that field is ok, what would pull the battery down if there is no electrical draw from lights?

b) Do these bikes normally not have enough power for lights at idle?

Thanks.

If I understand you right, you wired the HID lights back to where the stock light was wired originally. The '04 bikes were the first with the Kokusan ignitions and the stock out put to the lights is AC.

The reason the previous owner ran the HID lights directly to the battery is because HID lights will only work on DC power.

The problem is that the stock output is divided AC/DC with the DC going directly to charging the battery and nothing else. The AC powers the stock head and tail lights. Running the HID lights and stil having enough power to charge the battery is not possible.

To run the HID lights properly, you have to float the ground on the stator and run a larger regulator that will give you 100% DC power. This will give you enough power to run 35w HID headlight and still charge the battery.

www.trailtech.net has step by step instructions on how to float the ground on a kokusan ignition.

Maybe Sparks will see this thread and give you better expert advice, but I think what I described is your problem.

I should have been a little more clear. There are no HID lights on the bike now. The previous owner put HID lights on, but removed them when the bike sold. I cleaned up all the excess wiring left over and ran the power for the stock headlight (now on the bike) from the regulator/rectifier.

I've been reading the term "float the ground" in several posts. Can you explain what that means?

Neither side of the 12V stator windings can be grounded (ie connected to the chassis)when you try to get full stator output as DC. The is because the DC always has its negative grounded. When you put the AC stator output through a full-wave (4 diode) rectifier, it effectively connects one stator wire to ground, the other to the regulator/battery. Then when the AC output swaps over to the alternate direction the previous battery wire is grounded & the grounded wire is switched to the battery. This happens several hundred times per second (depending on engine revs).

If either stator wire was grounded, half the stator AC output wave would be fully shorted out. This is why the 12V stator winding must be completely disconnected from the chassis or "floated".

You can get DC from a grounded stator by using a half-wave (single diode) rectifier, but you lose close to half of the available stator output. The other half of the AC wave is blocked by the diode. I think this is how the DC charge output on the Kokusan is connected and is one of the reasons why it has such low output.