So my dad has a '78 sportster that keeps having the same issue.

When the bike has been ridden for a bit and is warm the starter will fail to crank the motor....you can hear the starter but it wont start the bike.

Now, we have recently replaced the battery and have always put it on a charger after this issue has come up. Are there any well known issues with this year and model? Possible issues that leech the charge off the battery when its running? Or could it be something else?

 

When you try to re-start when warm, does the starter turn over at all? Have you checked voltage before before trying to restart or are you saying battery is dead because bike won't turn over? A bad starter, loose connections, faulty solenoid can give impression of dead batt.

 

you can hear the bike turning over but its struggling to do so...when ive hooked it up to the charger the battery doesnt read as dead

 

Did you repolarize the generator when the battery was put back in?

 

I would check the starter or starter solenoid. When starting the bike cold take a reading on the amount of volts drawn at the battery. Then do the same with the bike warm. If voltage variation is quite bit, then I almost think the problem is with starter, but, I am no expert.

 

I dont know how to respond to your message about the electronic ignition but I will give it to you coil included (you pay for shipping lol) if you can tell me step by step how to wire up a points set up for my 82. jayflores0375@yahoo.com.