yes but since you have no regulator you are going to keep blowing lightbulbs when your batt is low especially that 6-volt headlight as the reg keeps everything past it at the specified voltage

Even this 12V LED one? I want to be sure of that before I go blowing up a 130$ headlight bulb lol

I guess since I have the rectifier/regulator combo from the guide you posted, is there a way to basically add the regulator to the circuit? maybe it is as simple as cutting a wire and sticking the regulator between it but that seems too optimistic.

the 12-volt one should fair better but you should try to hook up the reg just to make sure as those are some serious voltages as the rpm's rise the reg can ensure that the lighting system gets a reliable 12.7 volts and no higher

my setup needs to be completely rewired anyway and my lighting coil is dead so I'm just going to rewind the coil for 12 volts and use a 12-volt reg to supply 12 volts to the whole system but if your coil is fine just replace/ad in a 12-volt reg to get your equipment 12 volts just make sure you replace all the 6-volt equipment

Yep, I replaced the horn to 12v (screaming banshee mini. I tested it with a 6V battery and it works but sounds hilarious), I also popped 12v LEDs in the front blinkers, and the taillight, and the gauges, and got a 12v battery.

I need to see how to go about hooking the regulator up. I have the 12V combo rectifier/regulator here. I just need to see what wiring needs spliced in and if there's other step to be concerned with.

If it's an easy splice job, that would be great. The blinker and rectifier seem to just be some connector gymnastics, but since it's all crimp connectors, it's really easy to do.

having to cut or modify stuff to add in regulator support is a different story though....

Might work. First you have to understand the basics. The stock magneto has a fixed power magnets which means fixed wattage power output. Yamaha balanced the load (bulb wattages) to keep the voltage from getting too high... works well and was all they could do as electronics to build regulators were not available or too expensive... And 6 volt was used because the higher amps required for the same wattage makes it easier to achieve a stable balance.

Remember, the magneto has permanent magnets unlike an alternator or generator where battery power is used to change the magnetic field strength. So you can't really "regulate" the magneto output... the early regulators added load to keep the voltage in check.

There are two separate but interconnected systems... one for the headlight and one to charge the battery. The rectifier is on the battery charge side to crudely convert the AC off the magneto to DC to charge the battery. Yamaha grounds one side of the stator coil so they use a single diode to get "half wave" rectification.

AC output for stator looks something like this... a basic sine wave:



After the diode (rectifier) it looks like this (only the + part of the wave goes through to the battery +):



Lead acid batteries act sort of like a crude voltage regulator... if a little too much power goes to the battery, it gets hot and/or boils out the water to dissipate the excess power without too much voltage increase.

The AC (headlight) circuit was "balanced" on early systems and had the "bleed off" regulator on later models.

The topic of coil rewinding and all of that is somewhat of a "black art"... gauge of wire, number of turns, even the direction the coils are wound makes a difference.

You can also "float the ground" on the stator coils and use a full wave rectifier... but that could cause ignition issues on some models depending on how Yamaha interconnected the ignition source coils to the lighting coils.

Bottom line... with whatever you try, the magneto will still only put out the same wattage. And it was designed to be 6v not 12v so not sure a 12v battery will charge.

Volts x amps = power and because power remains the same, doubling the volts to 12, halves the amps. And lower amps means lower power losses due to resistance.

The biggest advantage to raising the voltage is that you'll have less power loss due to "friction" (resistance) in the wires and connections. So you might be able to run a higher wattage headlight because less power lost in transmitting through the wires means more power to run the light. That's why the big cross-country power lines are running at tens of thousands of volts... it wouldn't be efficient at all to transmit power over long distances at say 120 volts... the wires would need to be HUGE and the power losses would be great.

What several here have done is run a 12v headlight and dash lights with a Trail Tech 12v AC regulator and leave the battery stuff at 6v.

Or use the VAPE kit that gives you a modern CDI and more 12v output than you are likely to ever need.

On a budget, what I would do on a 74-on 175 is find a good used RT180 CDI ignition which already has a 12v lighting coil and with very little work will fit the earlier bikes. The early electrical system would have to be changed a little but only minor stuff... It's one of the projects I'm working on.

Anyway, in my opinion trying to force the stock 6v system to run on 12v is probably not worth the effort... you can't gain any real power.

One other option is that when Yamaha came out with regulators, they upped the stator output as they didn't have to be so careful with "balancing"... The later DT175's... if the wiring, switches, and connectors are decent... have a nice bright headlight on 6v. (I swap to an H4 reflector and use a 35w 6v bulb)

Good luck and have fun with whatever you do!

This all started because I couldn't find any good 6V blinkers, and the finnickyness of the 6V flooded battery killing headlights seemed like it would be something I experience often. I couldn't find any good 6V led bulbs. If I could've located the original style blinkers, this might have all been a different story to be honest!

I didn't think about the inability to charge. That would be a problem too. Uhoh.

I looked at that vape kit (the power dynamo ones on Amazon?), but it looked like too much was involved, and I thought the swap out would be smooth like the online guide made it seem.

I might still be OK overall, but I'm a bit worried.

how would I go about hooking the current setup into the regulator that is part of this combo unit I have? Or is that not something you can do?

Mark why did the rt 180 have lighting coils with no lights? Might could swap in an AT lighting coil as they were 12v if it doesn’t depend on magnets to function. I have read where those led lights are not that picky. I believe you could throw that ac current off the stator on it. Worse case Mark probably knows a way to shunt that ac voltage down some. Mark you remember reading the thread on the old forum from the guy in Cali that used the ac feed on an RT 1 and a 12 volt bulb? Remembered his handle socaldad. Wish I had printed that out.

I'm assuming this is the VAPE kit being talked about:

hvccycle.net/yamaha-dt100-dt125-dt175-rt...nition-70-98-799-00/

it's clearly pricey but im already all in on this 130$ unreturnable LED bulb (i scuffed it trying to shove it in the headlight housing.). Blinkers might be returnable at my expense since I never wired them up and just attached to the bike frame.....

but without useful blinkers at 6v this is all a moot point because I can't take it on the road!

that kit might be worth the price if it's that fancy and opens up my options. I guess I can see in the morning how bad the lighting is with 6v.

If you would have added in a factory regulator to the headlight as shown in the service bulletin the "finickyness" goes away. Lots of repops and turn signals out there with normal bulbs for decent prices...

I see now that you went with a LED headlight too... running it on AC either won't work or will likely blow it up. I'd suggest rigging everything up to run off the battery and then modifying the magneto system to only charge the battery. How many watts is the headlight?

I have no idea what a Honda Cub regulator is but could work. Do you have a wiring diagram?

P.S. One thing I noticed is you got a three wire flasher. Two wire is what you need. You might be okay if you don't connect the third wire which is a ground on the Yamaha... and flasher needs to be rated for LED's... and you might need to modify the flasher dash light or all four LED's might flash all the time.