1957 Johnson 35 starter turning slowly

[diveboss]

Bringing back to life a 1957 boat that came from the factory with twin Johnson 35hp motors that has been stored in a garage since 1963. Replaced coils,wires,points, impeller, rebuilt carb on both motors. One of the motors has a generator and is connected to a starter box that appears to have a solenoid and voltage regulator in it ( this is the one that is connected to the battery). The other starter box just has a solenoid in it.
Connected to a fully charged battery and both starters turn very slowly. Pulled the recoil starters and both motors fired up nicely and appeared to run well. Even after warming up both motors, tried the electric start and they both behaved the same, barely turning over motor.
It seems doubtful that both starters are bad, but I guess that is possible. Also unlikely that both solenoids are bad?
Would it be wise to jump start the starters with jumper cables bypassing the solenoids to see if they turn over correctly?
What is best course for diagnosis? Stay tuned as I'm sure I'm going to have questions about that generator and how to test I along with the voltage regulator.
This is my first post and any help is greatly appreciated!

 

[jimmbo]

Welcome to iboats
I suspect that those 60 year old wiring harnesses are showing 53 yrs of neglect. Bypassing the solenoids, DO NOT complete the circuit at battery, you DO NOT want sparks there, is one way prove or disprove that. Voltage drop tests and resistance test is another

 

[F_R]

Agreed, voltage drop tests are the way to go and save a lot of time. It is very unlikely that the solenoids are bad---especially both of them. Using jumper cables from battery directly to starter is an effective test--but deceiving if you don't have good connections at both ends (hard to do with jumper cables). And the jumper cables have to be decent quality. Those skinny el cheapo ones will deceive you too. The wing nut holding the big cable to the side of the motor is a ground connection. Remember that when checking connections.

 

[diveboss]

Thanks! I replaced the cables to the batteries as they were in rough shape, and cleaned the contacts from the harness to the motors and that seemed to do the trick!