Greetings,

I just picked up a '69 AT1 on a trade.  Quick background, the bike is clean but was not charging.  Upon inspection I noticed the voltage regulator/rectifier was missing and the wires from the magneto were not connected to anything!  I guess the battery has only been getting charged by charger.   I've found the bike has a DT175 crank and assuming 175  ignition system (but not connected to battery).   The original magneto and starter is no longer present.  On top of that each of the stator wires (although not connected) show continuity to ground and I get no charge through multi-meter when bike is running.

Problem/Issue:  I need to build out a charging system, don't want to spend money on electronic ignition at this point.

Question:  1) What stators will work on the bike with a 175 crank?  It's way past stock so I'm not worried about original at this point.  Will also need to pair up a voltage regulator.

2)  Are all these early bikes 6V?  Bike has a 12V battery in it.

2)  The Yamalube has been disconnected and running pre-mix.  The tach doesn't work, is that related to the gear bing out of the lube (pump in place, just disconnected)?

3)  What pre-mix ratio should I use? (I always run non ethanol in bikes)

Thanks so much!
Marshall
Hillsborough, NC

Welcome & blimey, almost too much information. I'm in NZ & we had mostly magneto AT1, in fact i have one. Mine has a 175 top end but cranks are the same on 125 & 175 so far as stroke goes--the up & down bit. But yes the electric start crank is shorter or different at least with an internal thread. So me wildly guessing i'd guess they've used a 175 crank so as to fit a flywheel mag. You mentioned DT1 which is 250 but that mag won't fit. So i'll take a guess you mean DT125 mag. Lost me train of thought now--gettin old. Anyway--if magneto then their's no battery requred to run it. Just black wire if wires still original from stator to plug coil under the tank & off ya go, hopefully not with a stuck throttle as need some way to stop it remember. I'll leave it there for now--need a cuppa & a lie down lol. Others will be along soon. Enjoy your time here. ps we love pics of course but looks like that option is out of order or was earlier. Cheers.

Thank you kind sir for the response. You are spot on, the bike runs with battery disconnected and a black wire runs to coil, and it's converted to a 175 crank. It has key but doesn't work to turn off bike, uses a kill switch. My challenge is I want to drive it on the road which requires lights and so I need to be able to charge the battery.

Is there anyway I can use the current configuration to get the battery to charge (note: stator coil wires show continuity to each other, but also to ground).

You probably have a CT ignition from a 69-73 175. 

Straight bolt on with a 175 crank installed. 

You should have two greens and a yellow...  possibly a white as well...  coming out of stator.  Make sure your meter is on AC volts and you have one meter lead to ground when testing for output.  Yellow will be highest output. 

Happy MarkT is here now. You said 12 volt batt but might need to go 6 volt as you'll have a 6 volt AC mag now. I wonder how a mag would charge a 12 volt battery unregulated just through a rectifier, might if you reved it hard enough off the yellow wire but that'd leave nothing for direct AC lights & doubt it'd keep up if you ran 12V lights on DC from Batt. So forget i said that. I Think--go 6 volt bulbs direct from the mag & an AC 6 volt regulator & no battery depending how legal you wnt to go. Or run a battery for auxilary stuff like horn, brake light & not much else & use a rectifier under the tank & play with the wires from lighting coil while checking charge to the Batt but leave yellow for the head, tail, speedo, tacho. Lighting coil is earthed so you'l get a reading between wires plus to earth. Just my woffling on ideas. Cheers.

Welcome along from the UK, over the winter months I’m wiring mine back up to oem. 

Welcome from  Tennessee  I like the Banner Elk area

Mark T and "support group".

Update:  Looking at similar stators on EBay it seems I have maybe a late 70s+ stator l and it is producing AC power as follows:  Yellow wire 12 - 34V, White w Orange Stripe - 2.8 - 8.5 V, Green 2.1 - 6.0V, Lt blue (male plug)  0.01V; also the black wire is running the bike off magneto with battery disconnected.  I still don't understand why it is showing continuity to ground through all wire but if it's charging that's all that matters.

Here's what I'm thinking, y'all set me straight if off track:  Since I'm producing 12V + on yellow wire, 1) keep the 12V battery (currently only being charged by tender , 2) install a 12V rectifier/ voltage regulator to battery keep battery charged.  3) figure a way to wire key switch to turn off bike so it won't start w/o key, 4) abandon (don't connect) the white/orange and green wires.  Is this reasonable?

Thanks!

Strange colors...  In the USA Yamaha went to a two bolt 120mm OD stator on 125/175 in 1974 and your engine has a two bolt 130mm stator mount so not sure what you have.  Australia and other countries might have kept the 130mm stator longer for the AG series.

(250's and larger Yamahas had a 130mm stator but it was three bolt)

What I would try is using the yellow and white/orange to a cheap 12v rectifier/regulator to charge 12v battery and keep AT1 wiring.  Might have to switch to lower wattage LED bulbs if battery goes dead.  Good thing is engine will always run even with no battery.  Bad thing is to get stock key switch to work for ignition the easiest thing would be to use a relay. 

Regulator/rectifier I'm thinking of would be with 2 AC inputs like these:

www.amazon.com/WOOSTAR-Rectifier-Regulat...ooter/dp/B07L3QWQ15/ 

www.amazon.com/Voltage-Regulator-rectifi...cycle/dp/B07L94NTSB/

I did this years ago for a friend who wanted 12v battery to charge for a helmet light for his daughter.  Bike didn't have lights...  I just used two AC stator outputs and installed regulator/rectifier and a 12v battery with a quick connect plug for her helmet light. 

P.S.  Blue is likely the neutral switch wire and doesn't actually go to stator at all...  if it's a Yamaha ignition. 
 

Thank you kind sir. The rectifier and it's mounts under the seat are MIA, will mod up some mount for an inexpensive 12V unit and wire as you noted. Previous owner has already replaced headlight with 12 halogen and a 12V is in rear as well. Will figure out a way to kill the bike with key off.

Thanks also for the info on the neutral cable. I have no lights in the speedo or tach, when I looked there are no wires running to them and the bottom holes are plugged. Another issue for another day...

Another questions - what premix ratio should I use? We used to run 16:1 and 20:1 in the old MX bikes back in the day but we were wide open all the time - that seems to be over "oily' for this little AT? The yamalube is disconnected, pump still in place and I'd like to get it back in service so I don't have to dick with pre-mix if I'm on the road somewhere.

Thanks again!