Just scored a used regulator CHEAP on FleaBay. I can't see any numbers on it - looks like it was painted at some point in the distant past. Seller says the regulator is a 443-81910-62-00 off an 83-84 TT600. From what I can find, it looks like it is a 6 volt job that should work exactly the same as the 498-81910-60-00 in the Yamaha service bulletin on regulators.



Now to figure out where and how to install on my current DT250A. Back in the early eighties, my then-local Suzuki dealer added a regulator to my original DT250A, sticking it under the right side cover under the oil tank - maybe onto the airbox cover? Been too many years and too much Jack Daniels and Bud Light since then!

I tried looking at the wiring diagrams in the Service Bulletin, in the Tech Library for the DT250A, and in a bunch of different threads here, and mostly just got confused. It looks like if I put it on the headlight bucket, I tie it to the blue wire that feeds the headlight hi-low switch?

The other install option that I was finding was to tie it to the yellow wire coming out of the stator, which it looks like I can do under that right side plastic cover. The only questions there are where to mount and whether that mounting spot has sufficient ground. What I was considering is mounting it to the airbox cover via one of its three mounting screws, then running a ground wire from there up to the battery for POSITIVE grounding (not relying on the airbox contact with the frame, etc. for grounding.). Will this work? Is the yellow the correct wire? It looks like the stator connector has four wires - yellow, black, green, and green with red (or is it brown) stripe.

Thanks, guys! I want to get the regulator installed before I try putting a different bulb in the headlight.

This part is best connected to wire that comes from the centre tapping of the generator and earth.

We have new ones if this one doesn't work

www.rexs-speedshop.com/epages/es143131.s...131/Products/RG6V-1B

www.rexs-speedshop.com/epages/es143131.s...Race/Yamaha_DT_Parts

TerryM, I just put that same unit 443-81910-62-00 (el-cheepo from screambay) on my 1975 DT175 today. Mine didn't come with one so LOTS of blown bulbs and battery problems . I put min on the frame under the tank. My bike has a set of thru holes outside of the rectifier mount that were spaced perfect. I just cleaned the regulator and paint off the frame and bolted it on. Sorry no pic. I'll Post some tomorrow.Then I didn't want to chop the main harness so I chopped into the left control harness on the controller side of the 6 wire connector, yellow/white wire. Used some vintage connector terninals and it worked perfect. I just have to put the wire in a sheath so it doesn't stick out going to the headlight bucket. 7.v +/- at the battery when I rev it out. NOT 9.8v... Good Luck Chris

My nickels worth:

That looks like the newer, smaller, version of the Yamaha OEM 6v regulator... I've also found them very cheap on ebay and never had one that didn't work... yet! (knock wood)

On the pre-76 US bikes the reason for tapping in up by the headlight is that with the lights off you are asking the regulator to absorb all the stator power for the headlight circuit. This might cause the regulator to overheat.

In 1976, the laws required an "always on" headlight so inserting the regulator anywhere in the circuit after the stator is fine... anywhere is also fine if you run with the headlight on all or most of the time.

My 74 DT360 had the regulator installed under the fuel tank. Also noteworthy was that there was no headlight off switch, only hi/lo beam. Not sure if this was a mod or from the factory.

IIRC, the 1974 DT360 originally had the on-off switch for the headlight located on the left handlebar mounted switch... earlier models had the headlight on-off in the key switch...

P.S. forgot to say earlier that running a ground wire to one of the regulator mounting bolts is something Yamaha did on some of the later models.

I may be talking out of my tailpipe in regards to the regulator on my 360. I believe it is actually only a rectifier. It was installed under the fuel tank, though. I removed it when the electrical was converted to 12 volts.

Good point Mark. I'm just looking for the best for the electric system, I am not an Engineer. If I can bleed off some electrons and not fry my battery..that's good. If the regulator loads up and I can light a cigarette off it ... that's a problem. I think that most of us will run with the lights on. In the old days BlackOut all day long. I put the reg in the light circuit and that did not change the voltage to the battery.

My 1975 DT250 doesn't have a regulator... I'm re-commissioning the headlight, brake light, etc (as were removed) but keeps blowing bulbs? Tested and when ticking over I'm getting around 15v

I haven't connected the battery yet, as a bit worried about applying 15v (will be more when rev's increase) to a 6v battery, but is this the reason the bulbs are blowing?

I'm no electrical wizard, or even close to anything resembling such. I can change lightbulbs, household outlets, and household switches, but not much else. And electrical diagrams are mostly Greek.

As I understand things, the mag will deliver variable voltage ranging from about 6 volts upwards to 25 or 30 volts of AC current, which feeds the ignition and headlight. A rectifier is also tapped into that feed, yielding an output of DC current of similar voltage. This DC current is fed to the battery, horn, and other lighting systems. When all primary lights are lit (headlight, taillight, and indicator lights in the speedo) and the battery is 'good', there is sufficient load that the excess voltage is tempered and bulbs don't blow. If something significant is missing, such as the battery or headlight, there is too much excess and the rest of the bulbs blow (including headlight if still present).

After about 1975, Yamaha started including regulators in the electrical system as a standard component. The regulator was tapped into the AC side of the circuit and kept the voltage down to a level where a missing or bad battery no longer doomed the headlight and taillight to the land of blown bulbs. At some point (don't have the service bulletin date in front of me), a service bulletin was issued instructing dealers on how to add regulators to pre-regulator bikes.

If this ain't right, somebody will jump in and correct me. Until then, I stand by the above, noting that it is worth EXACTLY what you paid for it!