79 35953A electrical issues! Please help

I’ve recently bought a used 35h motor. It’s had not been ran in what looked like quite some time. Unfortunately I do not have any history on the motor.
It was in shambles when I purchased it. But having a boat without a motor wasn’t doing me any good. And finding a motor I could afford was unexpected. I suspect when whoever owned it prior had it apart they couldn’t figure out how it went back together so just slapped it together and threw it in a shed.
Lower unit was missing detent balls and spring and all thrust washers. Now that I have the lower unit back together I’m finding issues I’m not familiar with. I have little motor experience and I’m learning as I go.
But the motor is returning over 16v to the battery when throttle is opened up (with cups on). Also the starter seems to want to engage while throttle is opened up and jumps up and smacks the flywheel. And then there is the arcing. You can see electrical discharges where the control lever connects to the throttle control rod linkage. I’m completely lost.

16V is normal with that unregulated system. "Opened Up" while on muffs is not. Don't do that!!

Vibration is causing that starter bendix to rattle and jump. There should be some sort of spring or damper on it. I haven"t looked at the parts book.

Hmm. Arcing huh? I'd have to think about that one.

Thanks for the responses. And I know that open throttle on muffs is never a great idea. My motor and boat are currently about 75 miles apart. Seriously though thank you for mentioning the high return being normal for that model. I can’t find anything in the book about the arcing. I’ve stretched the spring out a bit and the starter is not “self” engaging now. I still plan to replace it as that was my thought but figured hearing it from someone else would be beneficial. I’ve looked everywhere I can think of and cannot find anything about anything arcing like that.

Somebody will tell you that the magneto armature plate needs to be grounded. Truth is, there should be no electrical current passing back and forth to the plate, so no need for grounding. I'm thinking somebody has been messing with the wiring (??)

I have replaced some of the wiring that was extremely chewed up. It looked like the wiring had been on fire. So I checked the continuity of the wires and replaced the ones that seeded it. Replaced terminal ends. And such. As for the stator I don’t know if it’s grounded out or not. I’ve had it removed to check the condition of the wires coming from it to the rectifier but other then that I’ve done nothing with it. The wiring that is on the motor matches the diagrams in the seloc manual.

I have added regulators to these charging systems as I run various fish finders that are best protected by more than just the voltage moderating effects of a battery and a fuse. A very simple regulator like the external one used on the older Ski Doo Rotax motors, have served me well. They are weather proof and compact. I will try to get more details if your interested, but first you and Gator gotta get your problems solved.

Who, me? I got no problem with him.

No, sorry....I mean to solve his "motor's" problems. Sounds like it could be a mess.

And I’ve got no problem with fdrgtor. I appreciate all help and information I am given. I’ve been trying to get a picture or video of the arc jumping on the motor but it seems if the camera is out the ark doesn’t want to play. So maybe I keep the camera out It’ll stay that way... ok serious note the starter jumped again last night and when it dropped it just continued spinning even after killing the motor with the key. It only stopped when I disconnected the battery. This motor is seriously asking to be kicked.

Solenoids rarely fail in this manner. It is likely in the switch.

I’m sorry, laugh if you need to but.. switch? I’m confused

The switch that activates the starter solenoid?

Oh sorry for my ignorance I blame 30% of it on being awake way too early. The rest is all me I guess. I’ll look into the switch thanks