Mercury KG-7 Scintilla Magnet Rotor and Crankshaft Key – How do you remove them?

[Tracy Maxwell]

Hello,
This is my first post as a new AOMCI member – I have 2, 1950 Mercury KG-7’s I’m restoring (and a Mark 55A for a future project)…. question:

What’s the best way to remove a) Part # 20599 the Magnet Rotor and b) Part # 28-20625 the Crankshaft Key?

I have the original flywheel puller and have removed the flywheel nut, and the scintilla stator plate – next up is the magnet rotor…..

Do you have to remove the key first or will the magnet rotor slide up over it, then you remove the crankshaft key?

I’m planning to build a jig that uses the original flywheel puller and grabs 2 pieces of steel wedged underneath the magnet rotor by bolts, such that when I turn the flywheel puller main screw, it’d pull the magnet rotor upwards.  Is this a good idea?  Any advice is greatly appreciated.
Tracy Maxwell

[PM T2]

Good question, I never had mine down that far when I replaced the coils and did some point and condenser stuff. I did that work with the stator plate still on.

I’d say take the key out first. For removing the key, grab it with a pair of side-cutters and pry it out of its slot. You may need to file any nicks down that are raised on the sides of the key by the side-cutters. For the magnet part, somebody else will have to help you with that if you don’t have access to a manual.

PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

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Tracy Maxwell

[Tubs]

 

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

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Tracy Maxwell, seakaye12

[fastjohn]

The manual says nothing about removing the key before removing the magnet rotor.

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Tracy Maxwell, Tubs

[Tracy Maxwell]

Thank you so much!  I will grab my Pittman arm – in the meantime, I went and got 1/8″ piece of steel and was planning to fabricate something similar but not as elegant.  I used Microsoft Copilot (ai) and it said that the rotor comes off with the key in place and that the key will pop out after you lift the rotor.  I also read that because I removed the magneto stator plate, I’ve now somewhat demagnetized the rotor and will have to recharge it with the stator plate connecting to it before I put it back on the crankshaft.

Fascinating stuff

[Tubs]

 

 That’s baloney about loosing any magnetism on motors after WW-II. Those are permeate magnets and they it will be fine. I’ve had it off twice on one motor. You do want to be careful getting on and off so you don’t damage it. No banging on it.     

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

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Tracy Maxwell, seakaye12

[seakaye12]

That’s the problem with the evolving AI as a source for information.  AI gathers data from existing information somewhere on the internet.  There’s a LOT of questionable information on the internet….and AI may very well be using some of it to formulate an answer for you.

People re-post this information on forums like ours….and then that data as well becomes a source for AI in the future.

Bad information perpetuates itself in this manner.

 

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Tracy Maxwell

[green-thumbs]

THE BEST WAY,,, use the Mercury Service Tools!            Second best, tools that more or less do the job the same as  way as the Mercury Service Tools, ,                                  Worst methods involve use of hammer and pry bars,            Magnet rotors are easily damaged during removal or installation.

Mercury Service Tool Catalog is posted in the Old Iron  reference section. Those who work on Green Tank and earlier Mercurys will find it interesting and useful,

Good Luck Louis

Good Luck

Louis

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Tracy Maxwell

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