Having trouble getting engine on time

[TylerDurden]

Where is the starter from? A starter from a generator might be wound for 24V and run 1/2 speed.

[Diesel_Zuk]

It is the stock battery. I didn't wire the batteries in series, I did them in parallel, like you do when you jump start a car.

[vanbcguy]

If the wire goes to the starter then the other end should either be on the alternator or the battery. Weird that it is black though.

[air-cooled or diesel]

  If you don't, then the crank will move and the pump and cam timing will be retarded. 

if crank moves during the timing process its also possible to develop mechanical problems later. not just 'retarded timing'.

[air-cooled or diesel]

If the wire goes to the starter then the other end should either be on the alternator or the battery. Weird that it is black though.

any black wire must be first assumed as a ground, becareful, don't short out.
a slow starter would be; bad hot connection or wiring,
bad ground from trans ground post, possibly bad body ground,
bad batt or needs charge,
possibly needing a good hot connection from alt to batt, and alt grounding,
(bad starter),