Rewinding 250R Stator

[christph]

A couple weeks ago I was riding my 86 250R and a bolt came lose and damage the copper wire in my stator. It left me stranded 2 miles from my truck, but luckily someone came along and gave me a tow. Rather than spend 175 bucks for a new stator, I decided to try to and rewind it myself. Unfortunately there is not a lot of helpful information on the web on rewinding stators, and even less on 250Rs specifically. After a couple of weeks of trial and error I finally got a big fat spark, even better than OEM I think. So this information is for people who might want to try it in the future. All the parts only cost me 30 bucks, 20 for 2 spools of magnet wire and 10 for red insulating varnish. You will also need a soldering iron and a multimeter to check resistance and AC voltage.

Here are the parts:

18 gauge magnet wire (for the lighting coil)
34 gauge magnet wire (for the ignition)
red insulating varnish

Here are some of the basics I learned.

1. For each pole of the stator you need to reverse the direction of the winding, i.e., clockwise, counterclockwise, clockwise, etc. The lighting coil has six poles and the ignition coil has two.

2. Each pole of the lighting coil consists of approximately 50 loops of 18 gauge wire. You have to do this by hand so it takes a while.

3. Each pole of the ignition coil consists of a whole lot of loops--more than you want to count. With the ignition your target is more an overall resistance. The service manual says a good stator ranges from 50 to 250 ohms. I wanted the high side of that as more loops equals more voltage (there is a limit but it quickly gets technical). I wound mine to 247 ohms. Believe it or not, that is about 430 ft of 34 gauge wire for each pole or roughly 860 feet total. It is very thin wire. To make the winding go faster (and it still took about 45 min per pole), I threaded the wire through the inner tube of an ink pen--the one that holds the ink. It is rigid and small and allows for more even wiring than doing it with your bare hand. You can't do this with the 18 gauge wire because it is too thick.

4. I had a good stator (for another machine) and it tested at 180 ohms resistance. Kicking it as hard as I could produced about 50 volts. With my rewound stator I can get 80 volts. You can see the difference in the spark too, the latter is big and fat. I was worried about frying the electronics but I've run it and so far no problems. I plan on taking it out to the desert and hopefully I'll see some performance gains.

5. Be warned that winding the ignition coil is a very labor intensive process, i.e., boring. It took me 2 hours just to unwind and then rewind one pole.

6. You can get the insulating varnish from Fry's Electronics. It is perhaps not necessary but I like the extra protection. I got my magnetic wire from Remington Industries (see links below). They carry a wide variety of gauges at a good prices. Fast shipping too.

Here are some pictures:


http://www.remingtonindustries.com/

http://www.frys.com/product/4216944?...H:MAIN_RSLT_PG

[82 250r]

What is the purpose of the varnish? Avoid an accidental short?

Thanks for sharing this with everyone!

(Isn't the 18 awg for the ignition?)

[christph]

The varnish protects the winding from arcing, moisture, and oxidation. No, the 18 gauge is for the lights. That was the easy one to get right. I had to do the ignition coil several times before I got the numbers I wanted.

[6bt]

Nice work! I've been thinking about doing this to my XR650R, need more output.

Sent from my XT1254 using Tapatalk

[newby200x]

I tried this a couple years ago on a 86 125M, but just for the ignition pole. Very tedious process..the first time I tried it, I got it halfway winded and the thin magnet wire tore...so had to restart. It worked great after I finished it...I've since sold the machine, so not sure if it has still held up over time. Magnet wire is cheap compared to a new stator...and finding a good used one for a 86 125M was almost impossible.

[atc300r]

I have a new stator that came on a ebay motor for my 250r and the previous owner had a huge gob of solder on the ignition side and got into the coil and shorted it. I may try and fix it myself like you did. I found vids on you tube that shows how to do other coils but not Honda.