Kawi2strokes.com Forum

Sorry for posting non-triple questions here, but you guys seem to have good answers while other sites are filled with garbage answers.
I've got my DT250 running and have put the electrical system into service, well sort of. After only a few minutes of riding, the battery starts to boil over. Before you say it is the voltage regulator, these bikes don't have one. It is a 6V system. The headlight runs on AC, while the rest of the system is DC by way of a rectifier. The lights work as they should. I have checked the rectifier and it is good (continuity one way, but not the other). The battery is showing 6.2 volts (no internal shorts). Any thoughts on what to do next? A voltage reading with it running? I can't imagine what could cause this. I can't imagine the charging coil generating more than ~6.8 volts. It is not like I have ridden it much or put many RPMs on it during a ride around the neighborhood. I assume it is "boiling" over as I can't imagine the acid splashing out. Thanks for all thoughts.

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You are not old until you have more regrets than dreams! - John Barrymore (rephrased)

75 H1
78 CB400II Hawk
78 KE175

I think your system is about the same as the one in my DT100. As long as there is as much DC load as the system was designed for, things *should* be OK. So you should have an 1154 bulb in the tail light (I think that's the right number), and incandescent instrument bulbs similar to the originals would be good as well.

Do you have a stock type headlight? I know it runs on AC, but things can interact.

Also, I've seen some bikes with optional electrical terminal connections for sustained night lighting and intermittent night riding, one charging the battery more than the other. If you have an original schematic, does it show anything like this?

Edit: I just looked at a couple DT250 wiring diagrams on the net. It looks like there are two wires coming from the alternator that head toward the battery. One is Red/Green and the other is Green, or maybe Green/White. The Red/Green gets connected to the white wire that goes to the rectifier for night use (with headlight). For day use (headlight off) the other wire gets connected to the rectifier. If your loads can't keep the battery voltage under control, you might try connecting the Green (Green/white?) to the white wire full time and not using the Red/Green wire, so the lower level charging is always active.

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If it surges, that's normal, upshift.

Thanks Jim. I had to put all new bulbs in because someone ran it without a battery ( I suspect) and all of the bulbs were blown. I bought all stock bulbs except the headlight with is the 6V 35/35W halogen replacement. I will refill the battery and tomorrow run it and take a voltage check to see if I am getting much more than 6.8V. This is a 74 DT250A. Someone had added a voltage regulator to the headlight circuit (which I had removed to make it stock), but I have read that people often added these because the headlights were notorious for blowing at sustained high speed running. The on-line pictures of this optional regulator looks exactly like the one they had on this thing. Maybe it will shunt any excessive voltage upstream of the rectifier and prevent overcharging. I put it back on and will try again tomorrow. I cannot imagine the electrolyte is splashing out on a smooth pavement neighborhood road, so it must be boiling out. I am starting to wonder if someone replaced the charging coil with something for another bike. I will let you know what I find tomorrow afternoon.

_________________
You are not old until you have more regrets than dreams! - John Barrymore (rephrased)

75 H1
78 CB400II Hawk
78 KE175

Back in the day, I had a DT250 (loved it). As there was no regulator, the battery acted a the regulator (a large sink). I remember removing the battery completely (to save weight) & running a fully lossless system. I had to make up a load to replicate the battery (I think I used a zener to bias a transistor load). Worked a treat. That's all I remember (well it was nearly 40 years ago). Cheers.

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1971 H1A

It would be normal to see as much as 7.5 volts at the battery, Steve. But if it's much higher than that, something needs to be done. I wouldn't hesitate to try the headlight regulator, because you're right about the headlights blowing quickly. My DT100's headlight had both filaments blown when I got it, and I made a regulator before I put the original type replacement in.

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If it surges, that's normal, upshift.

Yep, I have many with the low (sometimes high) beam blown out from the many DTs I have. Even my current DT400 has this problem.

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This is true. Where I grew up the hills were so steep and long, when your ball rolled down the hill you just said "screw it"...

I just took the bike on a 4 mile ride and the battery boiled over again. It was not hot. I did a voltage check with it idling and at about 4500 rpm and saw between 6.2 and 6.9 volts DC. It should not be boiling over under these condition. I am out of ideas. Bad battery? What could be wrong with it. It shows 6.2 volts outside of the bike so no internal shorts.

_________________
You are not old until you have more regrets than dreams! - John Barrymore (rephrased)

75 H1
78 CB400II Hawk
78 KE175

You're right, it shouldn't be spewing acid at 6.9 volts. That's an ideal voltage. Even though it's reading 6.2 while not charging, I'd suspect something is wrong with it.

Is there any chance that for some reason the battery box is vibrating excessively? Maybe that could cause acid to overflow.

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If it surges, that's normal, upshift.

I could try to put some foam in the box. The roads in my neighborhood are very smooth, but the battery is a somewhat loose in the holder. Maybe it is splashing out. That would be ridiculous if it were as simple at that, but hey, I'd take it!

Also, I am thinking about trying the battery out of my ke175. It is only 2A instead of 4, but may be worth trying.

_________________
You are not old until you have more regrets than dreams! - John Barrymore (rephrased)

75 H1
78 CB400II Hawk
78 KE175

Foam around the battery is always a good idea.

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If it surges, that's normal, upshift.