Dt1 spark quit while running

 Hi,

This is a great board and I have lurked here for a long time learning stuff.
Well, finally I need to ask a question I couldnt find an answer for in the
search function.

Last week I bought a real nice 1974 dt 250. It had been garage stored 1999
and is in great condition. So I did the usual with a bike that hasnt run for
a while; cleaned out the carb,checked spark, etc. Lo and behold it started on
the third kick! I tuned the idle and set things so it ran and idled good. Oil
injection worked fine.

I hade a blast driving it around the neighborhood for about 15 minutes and
then it just quit. No spark!

So I dont know anything about 2 stroke magneto ignitions. How do I go about
diagnosing 'no spark' situation on this neat little  bike? ISomeone told me
that if you ran a magneto  ignition with a bad battery that could damage the
magneto. Any truth to that? Sho ' nuff the battery was toast but the as I
said, the bike ran fine.

Thanks for any tips and advice!

Thanks,
Dave R

 

I'd start with the spark plug.

Then the coil/HT lead.

Then the wiring connections.

--
BMW K1100LT  Ducati 750SS  Honda CB400F, SL125 & SH50
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chateau dot murray at idnet dot com

 
Had a 72 RT-2(360) that quit running after a ride down a railroad track bed.
Ran fine without the old battery connected. Only battery I've ever owned
that actually shorted out. Bike also ran fine with a new battery. IIRC
manual said to remove the battery for off road use, so it didn't need a
battery.

Don't get ahead of yourself. Don't recall any fuses but has to be a
rectifier between mag and battery. Check that all connections are clean and
tight. Check the points. Bad condenser(capacitor) could cause them to arc
and burn. Condensers age even when not in use. Cam lobe not being lubed in
decades might cause accelerated point block wear. Looking back you don't
mention having checked the points at all.

 Thanks guys...
I 'm a pretty fair mechanic and have checked the basics. All connections are
clean, I checked for spark with a new plug and the points check out O.K. .

When I crank over the engine my voltmeter shows a minimal amount of voltage
at the hot input to the coil. It's hard to read it when I'm kicking the
starter and lookling through the damn bifocals at the tester but it looks
like maybe 1 or 1 1/2  volts going into the coil. What is the 'normal' amount
of voltage from the magneto when kick starting?

Dave  




T Shadow wrote:

 
voltage

Haven't had anything with points for 30 years. Never needed to work on a
mag. I think I'd try checking coil resistance instead of voltage though.