Vintage Dirt Bike Q & A

recent CR 250 purchase with an MT250 motor. Magneto ground wire broke. Can magneto be rewired and if not where to get another? Also, power/discharge side of magneto is connected to points at same location as condensor and coil. With all three connected at the same location how can the points be effective? Is this wired properly? The manual stinks in relative to electrical.

eBay.com is your friend when it comes to finding parts.

Wiring sounds right in that it seems weird to me too. Honda made AC coils for their magneto bikes and DC for their street bikes.

I've fooled with coils and you get a spark when you put voltage across it and when you open the connection. Seems to jump in different directions under the two conditions.

I figure, *probably wrong*, is that the windings and magnets are producing current which the points are shunting to ground. When the points break they let the juice already present zap to the coil to produce the spark.

Sounds like it's wired right to me also. Yes, all the components seem to go to ground. I guess what makes this possible is the condensor, which temporarily stores the electical current. As far as the physics behind it are concerned, it's a mystery to me as well.

How does this bike have both Points and a magneto? What year bike?

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W.F.O. All the way!

MT's were made 1974, 5, and 6, so it has to be in that range.

IMHO: Honda was not really consistant with their bikes. Most of the bikes destined for street only used [battery, points, coil]. Most of the dual sports, but not all, i.e. 350SL used battery/coil, used the points/magneto, the early serious dirt bikes like the CRs used the magneto/points setup. ergo at least 3 types of coils, 12V, 6V, and 6VAC.

I seem to recall Honda was one of the last manufacturers to go to CDI/no points.

Back in 05 I had a coil rewound for my MR, very happy with the results. From the time I sent it out to the time it came back was 10 days and $45.00. Custom Rewind 2014 Pratt Hwy Birmingtam Al. 35214 800-798-7282 Gary Frye was the person I talked to. My coil had the windings damaged by what looked like someone using a screwdriver to stop the flywheel from turning while they removed the nut.

Gary,

GREAT bit of intel!! Many thanks!