Vintage Dirt Bike Q & A

I've got a 1976 Honda Elsinore MT125. I bought it for $550 in July 2012, and I've slowly got it running over the past few months. So far, I have replaced the coil, the spark plugs, the rear inner tube, the carb boot, cleaned the carb and and added a flasher relay, turn signal bulbs and a brake ligh bulb. It runs and rides well, it's a blast in the corn fields, but I want to ride on the street. I have the title, I just finished the IDOT safety course, but now I need the headlight tailight brake light and horn working. The lights all work by themselves, but if the headlight and tailight are on at he same time, after a few seconds, they both go dim, and when the turn signals are flashing, the other lights flash opposite. I did a few tests, and with the taillight on, and the headlight off, I let the battery charge for 20 seconds, then turn the headlight on and turn the engine off at the same time. When it charged at 1500 rpm, the light lasted 2 seconds after the engine is off, at 3000, it lasted 5. Then I performed he same tests, but left the engine running. At 1500, the light lasted 4 seconds, and at 3k it lasted 9 seconds. I was told to start with checking the regulator. Where is it on the bike? What other problems might this be? Here it is with the turn signal on.http://www.youtube.com/watch?v=c-3ruki5J3k here's a video

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1976 Honda Elsinore MT125
1990 Toyota Celica

New development. I tested the battery with a multimeter. Engine off, ignition off, it read 6.1 volts. The weird part was that when i turned the engine on, when i tested the battery, the numbers on the meter went totally crazy, they were changing too fast for me to see. Wacky right?

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1976 Honda Elsinore MT125
1990 Toyota Celica

sorry i cant pin point it for you. But i'd start with the wiring harness and check that there are no splices where they dont belong.

My bike 1974 , the headlight only works if the bike is running(gets it's voltage from the magneto). The signal,tail,brake and instruments lights work off the battery. I dont know if they changed the 1976 model to be different. if not then i would say someone tapped into the wiring to run the headlight off battery power. from the looks of things they may of used the signal light wire.

Hopefully someone will know if the headlight is wired different on the 1976 models. The rectifier is under the side cover, small square peice about 1". next to the signal relay.

I wired the headlight, and I believe that's what I did. Thanks.

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1976 Honda Elsinore MT125
1990 Toyota Celica

So the power from the magneto has to go through some kind of regulator doesn't it?

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1976 Honda Elsinore MT125
1990 Toyota Celica

Ok. So I plugged the headlight directly in to a wire spliced to the same wire the coil's connected to, and it killed the bike. So I have a stator problem right?

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1976 Honda Elsinore MT125
1990 Toyota Celica

First off, do you have the original wiring harness or are you trying to make one?

Second, you might not have the correct stator. there should be 3 coils on it.

Inside your headlight housing, coming off the sealed beam are 3 wires. Blue,green and white.

The blue is the high beam, green is the ground, and white is the low which is also connected to a resistor(10 watt,3.61 ohm)

the white wire and the blue wire goes to the dimmer switch on the handlebars.

Coming off the stator are 4 wires, bk/w. w/y. lt g/r . y.
the white/yellow goes to the headlight switch on the handlebar. from there it is a blue/white stripe to the dimmer switch, from there it goes to the headlight as either blue or white.

the bk/w wire from the stator is a seperate coil from the light coil.

the yellow wire from the stator, also a seperate coil goes to the rectifier, a red wire comes off the other side and goes to the batteryand the 10 amp fuse.

the light green and red wire from the stator goes to the nuetral switch located in the side cover next to the flywheel .

Unfortunately, a previous owner removed the lights, and the next owner started to reinstall them, so the wiring harness has been fairly butchered. I plan on replacing the wiring at some point, but right now I just need to get the lights working so I can take the riding test, I am just working with what I have. I haven't been using the resistor. I assume that's the long cylindrical part with the white wire? I noticed both the white and blue wires have double female connectors. Is there something else that goes into the high beam? I greatly appreciate your help.

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1976 Honda Elsinore MT125
1990 Toyota Celica

ok. So here is the condition of the wires coming off the stator. The insulation is cracked, and one of the wires consists of about 3 strands. But, in following the w/y wire, I found that it was cut. When I connected it to the head light switch, it worked. Now on to the taillight. It has the same dimming problem. I also noticed yesterday, that the battery was making a bubbling sound with the engine off and the ignotion switch on. Do I need a new battery? Again, thanks for your help.

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1976 Honda Elsinore MT125
1990 Toyota Celica

On the double connectors for the headlight.the other blue connector goes to the high beam indicator. the other white goes to the resistor.

the taillight wires are Br, G/Y. and G. the G/Y goes to the brake lever on handlebar if it still has the brake switch and the foot brake switch. The other side of the handle bar brake switch is BK and it connects to the Bk connector in the headlight housing.

the Br wire is a little trickier to follow as it changes color .from the tail light it goes to the big harness connector under the headlight bracket, but also connects to the G wire off the kill switch. from the big harness connector ,the Br wire comes out Br/W and connects inside the headlight housing to Same color connector.

The G wire from tail light connects to same color connector with the ground wire from signal lights. those wires are usually black and have a green band at the connector.

your battery may be good, the rectifier may not be. It is a diode and allows current to flow in one direction. you can check it with a meter on the ohm scale. put leads on each terminal and see if you get a reading. then reverse the leads and see if you have a reading. you should only have 1 reading and open when you reverse the leads.clear as mud yet?

now to make sure the wiring is right on the charging circuit. from the stator the Y wire goes to the rectifier with the triangle. a R wire comes off the other side to the 10a fuse and positive side of battery. The negative side of battery is connected to all the green wires.

The tail light bulb is 6 volt 32 watt.the signal light bulbs are 6 volt 17 watts.

I'd say its clearer than mud. It's more like skim milk. Unfortunately, s much of the wiring is not original, the colors may or may not be accurate. I will perform the tests tomorrow. So does the fact that the headlight works off of the stator mean that the stator is good?

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1976 Honda Elsinore MT125
1990 Toyota Celica

yes , your stator appears to be good. Good luck

I tested the stator. I'm not very good with a multimeter, so I took some pics. Here are the test results. I did get a reading both ways at 2000k. I also traced the yellow wire back from the stator, and found that it was completely broken. I will be soldering that in the near future.

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1976 Honda Elsinore MT125
1990 Toyota Celica

I dont know if reading it on that high of a scale will affect the readings or not, especially with a digital meter. Just use the 200 Ohm scale and see if you get a different outcome.

Since i can't see how you'r doing the readings, let me re explain. Do not hold the leads on the terminals with your fingers, it will mess up your readings. Place the rectifier on a surface and then put the leads on the terminals. just make sure the leads are the only thing touching the terminals. Then change sides with the leads and check the reading.

You should have a open circuit in one direction and a ohm reading in the other diredtion.

I repaired the broken wire, and I am getting 7.4 volts at the battery when running. But I repeated the rectifier test at 200 ohms, and was reading no connection either way.

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1976 Honda Elsinore MT125
1990 Toyota Celica