Battery is fine, does the same thing when starter is directly connected, i have also added my boster pack and the same thing happens. Engine has 2 earth straps, just to be sure. Both starters spin freely on the bench connected to the jump pack.
I have two old starter motors both are quite well used both have the same problem.
Please can you take a look at the photos below.
Is the cog here to worn (photo 3)? Its a re-faced fly wheel on a completely rebuilt engine (I have removed the plugs to remove drag).
Could it be the engine is quite "tight" after the rebuild and i will now need a more powerfull starter motor?
I cant work out how to remove the cog either? The book says just remove the split pin on the end of the shaft... No split pin, i cant see how i get this off?
No split pin, how do i remove?

how the hell do i get this off?

Is this too worn? Is this causing my issue? Its a new engine and a re-faced fly wheel.

Please help i have spent 2 days looking at this and got no further, should I just buy a high torque starter motor?
