1989 force 85

good morning everyone. i am new to the boating world and purchased a 1985 bass tracker bass boat with a 1989 force 85. as i understand it the previous owners dad had replaced a piston and did not put all the wiring back onto the motor. i have repaired all the wiring and have verified this through removing the plugs and grounding them out to verify spark. when i try to turn it over with the plugs in the starter will barely turn it over. plugs out it turns fast. i know this motor has sat for atleast a year. do you recommend tearing the powerhead back apart and relubing the con rod journals? or is there something ive overlooked. starter tested good at shop. any help would be appreciated. i got a deal on this boat @ $500. lady thought it was a 15'...its a 17' 10"

Welcome, fill out the profile.
Location? You might be close to someone who can help?
Do a compression test before you do anything else.
Then check the connections, behind the starter is the main ground.
Then check the battery connections.
Post your results.

my dad had a 1988 force 125 and the starter started acting like that wouldn't turn fast enough - i picked up a new one and it fired right up - found new one on ebay for about 70 or 80 bucks i believe.