DT250A build and magneto upgrade

[Stew]

Hi all
Im new to posting on forums so sorry if i stuff it up.
Im in the process of building a 1974 DT 250A from a total basket case, well milk crate case, 3 of them.
I hope to finish up with a street tracker look with under slung pipe.
I didn't want to spend $700 on a power dynamo, so i did some research and came to the conclusion of using a 11 pole stator and mag for a GY6 Chinese scooter, the parts are cheap and plenty full. Into the bargain you get electronic ignition and 12 volts.
I also found a racing CDI unit for a Yamaha jog as it's a 2 stroke.
The mag fits with the woodruff key being stepped, easy. I cut the original coil mountings off the stator plate and drilled 2 holes to mount the new 11 pole stator, made a plate to mount the ignition pick up.
I had to cut away some of the engine casing and the cover to clear the ignition pick up.
Plugged it all together, span it with my drill and we have a spark. Next i will have to get a strobe timing light and move the pick up actuator in the correct place. the mag is about half the weight of the original. I have a reg rec to suit.
Stator $26, mag $26, reg rec $22 and the racing CDI $24, all parts found on ebay and Australian stock.

[JonW]

Blimey thats some lateral thinking.

Programmable ignition would be better, whats the curve of the jog cdi I wonder?

[mboddy]

Any curve is an improvement. The DT250A didn't have a curve.

[gman]

well done on the upgrade stew. look forward to hrearing how it runs.

[mboddy]

If it fits the DT I think it should fit an RDLC.
From the D model DT on the crank taper was the same as RDLC and RZ.
I hope the A model DT has same taper as D model?

[JonW]

Yes, but does the jog have a curve? many older bikes dont have much of one, its quite lineer, the moped might be the same?

[mboddy]

The race CDIs show a curve on the box.

[ged]

Nice work Stew!

I wonder what the output would be? The new stator looks to have more wire in it that the original winding, so its probably more!

The weight saving in itself is reason enough to adapt this, plus losing the points and condensers, all for 100 bux! Bargain.

[JonW]

Cheers Mark, thats better than I expected.

[Stew]

That's the CDI i have, i think it will be ok, the old points set up has no curve. I picked the racing CDI from the jog as it's a 2 stoke and it shouldn't have any advance.
It took a lot of research to get a con rod kit, i couldn't find one for the 1974 DT, no body could tell me the difference between models. I took the plunge and bought a Royal 5x5 kit from Yambits in the UK and a piston from the later DT250MX, ring pegs in the same place, yep they are all interchangeable, the little end bearing with the kit is not the same size as the original, the rod eye is bigger on the 5x5 rod, it has less needles and bigger diameter and still uses the original gudgin pin.

[OzzyElsie]

Excellent work Stew. I'll be interested to hear the riding performance after you have kicked it in the guts and gone for a ride. Thanks.

[hybrid]

Nice work!