Hodaka 94A carb and wiring

[james92691]

I have a Hodaka engine for a Wombat. The Mikuni carb has 2 small brass outlets (they look like gas outlets but are only about 1/8 inch diameter) One is near the bottom and the other is about half way up. Does anyone know what I am to do with them.? Also, on the wires for the lighting I believe that the green one goes to battery positive and the blue one goes to battery negative. That leaves the yellow one all lonely...

[Zyx]

Overflow venting. You can either put lengths of small tubing on these and run the tubing down and out so overflow doesn't flow over you paint work, or ignore them.

[james92691]

Thanks dude, that was pretty simple

[viclioce]

What did you want to know about wiring? ; D Victor

[Bullfrog]

Having some small diameter tubing installed on the overflow vent fittings - with the ends of the tubing generally pointing down - helps assure that miscellaneous grunge does not accumulate and plug the overflow vents.

Full wiring diagrams are available on this site - they should provide the answers you need on wiring.

Ed

[james92691]

I think I have a handle on the wiring. Ignition wiring is just a simple plug in. On the lighting circuit I use the green wire to white wire on selenium rectifier ….from there the red wire on selenium rectifier goes to one side of voltage regulator (12 volt conversion) The other side of voltage regulator goes to positive on Battery. Battery is grounded to frame on negative side. The blue wire goes to negative on battery. May be using battery tender if current from engine not sufficient to charge battery. Have not tried this yet. Waiting for delivery of rectifier from Strickley Hodaka and regulator from aftermarket source. This is a Wombat engine put in a 1969 Super Rat frame with all custom components.

[rlkarren]

II believe that the green one goes to battery positive and the blue one goes to battery negative. That leaves the yellow one all lonely...

Both the Green and Yellow wires are hot wires. you should also have another yellow/green wire which is also a hot wire. All three wires are delivering AC current, (when the engine is running). The blue wire is ground. Black wire is hot to the secondary coil under the tank.

The Wombat lighting coils are wired in series. The yellow and yellow/green wires are the output of ONE of those coils, (about 18W), and the green is the output of BOTH coils, about 45W. Same relative voltage.

The yellow wire is used to charge the battery via a selenium rectifier. The rectifier converts the power to DC current and also cuts down the voltage to a trickle for battery charging.

The green wire is used to power the headlight/taillight.

And finally, since power output is relative to engine RPM, use a voltage regulator.

Hopefully this helps. You don't have to wire your bike this way but I think knowing what the wires are will help you make your own decisions.

There is a wiring diagram that I simplified for a Model 94, in the Tech Tips section that can help illustrate what I've mentioned here.

$0.02

Roger

[Zyx]

I wasn't aware the Wombat lighting coils produced enough voltage to maintain a 12V battery. Thought the output was somewhere near 8V AC. Book says "under 9V at 8,000 rpm." That won't support a 12V system.

[james92691]

rlkerren sounds like the wiring diagram talking to me. Very informative. Thanks for the info. I don't have the parts yet so I don't know how this will turn out. I will be using a 12 volt system. Maybe I'll have to use a battery tender to keep the charge up. The only question point in my mind at this time is whether I ordered the correct voltage regulator or not. I may have to try a few types to see what happens. I thought it was important to go to the forum before starting so I could get some ideas. Everyone is so helpful

[Zyx]

I would posit that if the system can produce no more than 9V it won't matter what kind of a 12V regulator you use because you will never hit the limit, which on a 12V system would be somewhere north of 14V.

[Bullfrog]

I certainly don't have good understanding of the electrical dynamics involved with the magneto lighting coils and the effects of installed load, but I have measured 30+ volts AC from my Wombat 94/94A lighting coils (prior to installing a voltage regulator - probably open circuit, but I can't remember for sure) . . . and have run a 100 watt, 12 volt sealed beam in a direct wired (AC, no battery) trail lighting system. That sealed beam would make Ponderosa Pine bark smolder at 50 ft.! The system I'm running utilizes a standard aftermarket solid state 12 volt voltage regulator, but, again, no battery and not street legal. So, I'm sort of feeling there is plenty of electrical power available.

I suspect the 9V at 8,000 rpm specification is with all the standard lights installed and working, and the battery being charged -- even so, I can't explain how that translates to the amazing brightness of a 12V, 100Watt sealed beam when installed with a 12V regulator - I just know it works.

Ed

[Zyx]

Ed,

I don't have an answer. I do understand electrical circuits sufficient for purposes of a bike. I would have to guess at the answer, but as the book value was limited to 9V, I would say either the Japanese lied about the potential way back when and no one knew, cared, or found out, or you have an outstanding system.

The Wombat is stated to have a 45 watt output at the same revs as it has 9V~. Watts = Volts x Amps. Pretty simple. 45W=9Vx5A. The potential of the coils is (if not limited to) at least a result of the windings in terms of gauge and number. More wire, stronger magnetic field, more potential. I would not be surprised to find a magneto making more voltage than rated, but only if revved higher or rewound. The original system did not have a voltage limiter, and even with all the lights on at the same time, the rated draw was only 45 watts more or less, which would not peg the system but rather falls within the rating. If your system puts out 30 volts, the original 45 watts of draw would not have limited voltage to 9V. Clearly, since you have used a 12V lamp of substantial wattage. But such output, without a limiter in place, would burn out a 6V lamp instantly, cook the battery, and burn the tail lights and all the rest.

Since there are two output coils I would have to study the wiring diagram to see how the bike originally used those coils. I doubt they were tied together, but would expect they ran parallel, one coil running some things, the other coil running the rest. I would also assume you are using both coils in tandem for a single voltage source, and perhaps this is part of the answer.

Another part of the answer may be that you measured 30V with an open load, that is, across a multi meter instead of across a load like the headlight. Multi meters don't exert a load so perhaps what you were seeing was a reading higher than you would if you checked voltage at various points in the lighting system. Without a load and at that voltage, amperage would be minimal, but as soon as you introduce a load, amperage will rise and/or voltage will fall, and things will start to get hot.

At some point, if the coils will produce usable 30V and you run a limited circuit with 12V lamps, you are going to get something hot. Amperage will rise as wattage demand rises given a static voltage, which is more or less what the voltage limiter does. The coils may not survive long if routinely subjected to a 10 amp load when they were intended to have no more than 5, so I wouldn't run anything more than a headlamp, and frankly, it wouldn't hurt to use a battery in your system.

Since you are running the bike this way, I would say you are in the best position to verify the variables, loads, voltages, and temperatures. But as for the original system being functionally limited to 9V because of the various lights it had, I don't think so. I would like to think that having a battery in circuit would buffer voltage spikes, but 30V in a 9V system isn't a spike, it's a nuclear crisis. I wish I still had a lighting system on my bike to have something to experiment with. I can sort of see why you can run just a 12V headlight, but I can't see why the original system was limited to 9V without a voltage regulator if the system will put out 30 V.

[Zyx]

The only 125 wiring diagram I can find shows a current limiter in circuit in addition to the rectifier. That would explain a 9V output in the book and a 30V output without one. Take out the 9V replace with a 12V, use a 10A fuse, and I suppose you could fire a 100W lamp.