The Yamaha NOS

I had the same problem here, tryd 12v bulbs, but this is no silution in the long run, the only thing that solved this, was a 100w resistor paralel to the headlight, this way the alternator is under a higher load, thus produces higher voltage. I put it under the headligkt between the fotks, so it can cool. Gets pretty hot!

Sorry, i mean alternator produces lower voltage

Hi, yep see your other post & all good. On my ride to work DT250 about "77 model 25 years ago, still magneto not cdi, i ran twin headlights unregulated, had no battery to soak up the excess. Single wire 6 volt regulator sorts over voltage ok but don't think i ran one then as had two bulbs working good. Probably tried different wattage till i got them bright enough with no chance of blowing, unless one blew & then the other would follow--maybe i had a regulator just incase. Worked in the Yam shop so had old bits to pick over. Probably ran two 15/15 bulbs [30 watt] plus a 5 watt tail or maybe a 3 watt as had 10/3 stop tail but i never had a stop light. Half the things we used to do you'd never get away with these days. 100 watt resistor sounds high, would it be 100 ohms? do you think. I'm not good on converting electrical terms ohms/watts etc but have a suzuki scooter resistor here from the "70's & i think was equal to a scooter headlight bulb so you could ride with the park light on & not blow the bulb, not sure of the ohms resistance though. I call it a park light but it was magneto driven off the headlight circuit then if it 'was' parked, you could turn the key past stop & the battery would power it up. Yamaha had something similar on some early scooters. Anyway, woffling about not very much. Cheers.

Just searched my expired listings on trademe nz & found my resistor. Has 3.5 of those ohm thingies lol or 3.5 thousand? [doubt it] how do you read it? I see i listed it as a suzuki lighting resistor but was a while ago now. Actually does the letter K mean resistance? so 3.5 ohms resistance--hell i should know all that & must brush up on all i've forgotten seeing "Old is Back", well on this site thank goodness. Regulator is the way to go nowdays though & never had an adjustable single wire one but just a yamaha std 6 volter but adjustable sounds extra good.

actually i'd be a lying wally--i might've run 12volt twin headlights to not have them blow with no battery. If 6 volt i'd have run a regulator to save the bulbs. I know on my RT1 i ran an xj650 big diameter light with a quartz 12volt high wattage bulb unregulated & damn near melted the tar seal but never blew. Just a bit weak at idle till about 1/4 throttle. No battery to soak up the drips of course. Long time ago.

Its a 12Volt/30watt resistor not 100watt like i posted before, sorry,

We've a fair deal of experience with these systems. If you are keeping it 6 volt a AC regulator is the way to go.

www.rexs-speedshop.com/epages/es143131.s...B/?ObjectID=46098543

If you want to go 12 volt we have this kit available:

www.rexs-speedshop.com/epages/es143131.s...131/Products/DT-12VC

The advantages of the 12 volt kit is that it replaces all of the many variations and changes Yamaha made to these generators over the years with one new winding designed specifically to work with all systems and give sufficient output for all systems. It fits all of the 250/360/400 4-magnet generators except the TY250 twin shock.

It uses a proper regulator that gives much better power control and improves the electrics no end.

where do you install the regulator on the bike? i installed one splicing it the yellow wire after the mag. It didnt work. Do you have any ideas?

Hey Guys Im having the same problem. I just went thru 2 of Pobits headlights thinking I had something wired wrong. So are y'all saying I can get a 12v light with a regulator? Im really trying to get everything working so I can have it road ready for an around town bike