1986 Johnson 48hp wont turn over fast enough

[NYGiants]

Bought a 48hp johnson non running and I am trying to get it running. The motor will not spin over fast enough when the plugs are in to start, but with the plugs out it will crank over great. New battery ends, compression is good and the motor is in pretty nice shape over all. Any ideas? Primarily a fresh water motor. Tried a different battery as well

 

[flyingscott]

Check all connections and make sure they are clean and good grounds. If everything is good you may need to take the starter apart and clean.

 

[NYGiants]

why would the plugs being in vs out make a difference?

 

[racerone]

With the plugs in the starter has to do some compression work.------Take the starter apart as it is elegantly easy to work on those starters.