Motorcycle Questions? Ask a Mechanic.
The most common problem on that era of Sportster is a bad ignition switch. It isn't too hard to diagnose but requires a volt meter to do so. I can help you with that if you want to try it yourself. A good "key wiggle" can sometimes get you going again in the short term. The internal contacts get worn and burned causing it to stop passing power properly.
A new switch is available in the aftermarket for about $35.
I hope this helps. If so, please leave a Positive Rating for my service. Thanks, P.J.
You're welcome, take care. P.J.