The cold oil can be factor. Cold Motor Oil increases drag on moving engine parts and reduces cranking speed.

 

Not the oil. I start my bike when its 30 degrees here with 20w50.

1. Check battery cables (tighten)
2. Check grounding strap (tighten)
3. Remove battery and load test on a motorcycle tester
4. Check VR
5. Check rotor/stator to see if it is charging.


If you need a battery get one from East Penn Deka manufacturing. They make all the HD batteries but their dealer charge less than HD dealers. I saved $40 on mine.