1968 Johnson Tr-10r 55hp wiring help

[Kharrity86]

Need some wiring advice on a 1968 Johhson TR-10R 55HP. I just replaced the engine side wiring harness. The previous owners had the rectifier wired different from what the wiring diagram shows. See attached pictures. The red wire coming from the ampere gauge is connected to the center wire of the rectifier. Ampere gauge is connected to keyed hot. This leaves the wire in the engine harness connected to nothing. Is this correct?

 

[F_R]

Is your heart really set on an ammeter? The motor wasn't really wired for one. OMC avoided running the charge current all the way forward and back, which would require heavier wire gauge. May I suggest a voltmeter instead of an ammeter? Voltmeter hookup is simple. Connect one side to the stack of wires at the switch and other side to ground. And the voltmeter is more meaningful anyway.

 

[Kharrity86]

Is your heart really set on an ammeter? The motor wasn't really wired for one. OMC avoided running the charge current all the way forward and back, which would require heavier wire gauge. May I suggest a voltmeter instead of an ammeter? Voltmeter hookup is simple. Connect one side to the stack of wires at the switch and other side to ground. And the voltmeter is more meaningful anyway.

Thanks for the reply! Nope I don't care if the ammeter works or not. Just want to get this thing cranking over so I can check compression and see if its worth messing with further.
Should I just wire the amplifier like the wiring diagram shows? I wasn't sure if there was a good reason why they did it this way.

 

[F_R]

I know the guy that drew that diagram, and it is correct as originally built.

 

[Kharrity86]

I know the guy that drew that diagram, and it is correct as originally built.

Thanks! I'll connect the engine harness wire back to the center wire of the amplifier and see if It'll crank over.

 

[jimmbo]

OMC avoided running the charge current all the way forward and back, which would require heavier wire gauge. May I suggest a voltmeter instead of an ammeter?

When did OMC drop the Ammeter? I remember our 1963 40 Electramatic having one, it certainly revealed when the Generator failed. Our 1965 90 Starflight also had one and it was pinned on "+20" whenever the Motor was above 1800rpm.

 

[F_R]

For the most part, the ammeter went away with the DC Generators. Of course, there exceptions. (The early high output alternators would be some, such as your Starflite)

 

[Kharrity86]

Is this ignition system 12v? Owners manual states some models covered are 6v and some 12v but I can’t seem to find more information.

 

[Kharrity86]

Is this ignition system 12v? Owners manual states some models covered are 6v and some 12v but I can’t seem to find more information.

Never mind! Just looked at the wiring diagram again. Thanks for that!

 

[racerone]

The 6 volt system was last used in 1956 I think.

 

[jimmbo]

In 57, OMC did switch to 12 volts

 

[Kharrity86]

Got the motor turning over and tested compression. 120 psi on all 3 cylinders. So far engine will not start. I'm going to get a flywheel puller and check the points tonight. Any suggestions or tips for trouble shooting ignition?

 

[jimmbo]

Point Gap is 0.010"

 

[Kharrity86]

Thanks for those pages! Is that the official OMC service manual? The Clymer I have doesn't seem as good.

 

[Kharrity86]

Is 120 psi ok on this motor? I pulled all plugs when testing but did not have the throttle open.

 

[Crosbyman]

opene throtlle won't change much. 120 ok ...if it works don't fix it !!

 

[racerone]

Throttle plates do not need to be open on a 2 stroke to test compression.

 

[jimmbo]

Thanks for those pages! Is that the official OMC service manual? The Clymer I have doesn't seem as good.

No. It is a 3rd Party manual that was far ahead of the Clymer and Seloc manuals. I can't remember who published it, as the first several pages are missing, and so is the Spine. It covers most makes between 1955 and 1971. It was the 1972 Edition, my dad bought it in 72

 

[Kharrity86]

Got it running! Installed a new CDI box. These are on Amazon for $290 right now. CDI 113-7123

 

[Kharrity86]

Video of it running for the first time since about 1988.