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Cushman Wico Magneto Help


Bobby Crevelli
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We are a highschool autoshop class based in SoCal and are currently working on a 1946 Cushman scooter, with a 4 volt Wico no lights magneto. Our current problem, and the problem that we have been having for the past several months is that we cannot get a spark on the spark plug. We have bought the spark plug tester recommended in the "how to rebuild the Cushman Cast Iron Engine" by Jim Fredrick. As well as we have tried numerous things with the magneto as suggested by cushman repairing experts. Such as we have removed the gold film from the condensor in order to ground it, we have fully cleaned the magneto plate, we have removed all oil from the ignition points, and tested to make sure that it is grounded. We have put the shims in the ignition points arm. As well as everything on the magneto plate is less than a year old, except for the ignition coil which is just over a year old. Yet, we are still not getting any spark on the spark plug tester. If any help or suggestions can be provided, it would be much appreciated. 

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I'm not a Cushman expert - there may be some here - but a couple of things. 1. make sure the points are not only grounded when closed but un-grounded when they are open. The circuit must only go to the coil and condenser when open. It will read to ground trough the coil so check with the coil unattached.  2. Magnet timing. Make sure the keyway in the flywheel is not worn, the key offset, or anything twisted. The magnet must pass over the coil at just the correct time.  3. Condensers can be fickle can you get another to try?

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In Vespa scooters the magnets in the flywheel can get weak and no longer produce enough magnetic field strength to generate a spark.  Don’t know if that is possible in your case but just throwing it out there for consideration.

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They do lose magnetism over time. A  good auto electric shop can remagnetize the magnets on their growler. It only takes a minute, they usually don't even charge for this service.

A simple test is to see if a screwdriver sticks to the magnet, it should have a strong pull.

Edited by Rusty_OToole (see edit history)
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Find an old small engine or outboard dealer that has a Stevens coil machine or similar.  We used Stevens coil test machines on Johnson/Evinrude outboards to test coil output and find defective coils leaking primary voltage off to ground, opens, etc.  The engine in the Cushman is likely a Wisconsin.  

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2 hours ago, Str8-8-Dave said:

Find an old small engine or outboard dealer that has a Stevens coil machine or similar.  We used Stevens coil test machines on Johnson/Evinrude outboards to test coil output and find defective coils leaking primary voltage off to ground, opens, etc.  The engine in the Cushman is likely a Wisconsin.  

The engine is a Cushman Husky. Cushman always built their own engines until the OMC merger. Be sure the crank seal protrudes a quarter inch to properly center the mag stator plate

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22 hours ago, Rusty_OToole said:

A  good auto electric shop can remagnetize the magnets on their growler.

I have a technical issue with this statement. A "Growler" is an 'open pole' AC device. It is impossible to "Magnetize" predictably with an AC magnetic field, however it is VERY easy to DEMAGNETIZE with an AC field.

My point is to keep someone from doing damage by not knowing how to perform the procedure.

In Rustys defense, I am sure it would be possible to set up a growler with DC voltage to form a magnetizing tool, it is just not the norm for a growler.

A good older auto electric shop is an excellent place to check!!!!

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In the dim and distant past had a local auto electric shop recharge magnets for small engine magnetos including one for an R69S BMW motorcycle. I thought they used the growler but maybe not. The shop closed years ago so too late to ask. They never charged me but I knew the tech and he knew I worked in local garages.

Better magnets never failed to result in better sparks. There isn't much to this type ignition. If the points are good and the coil condenser and wiring is good and everything adjusted properly they work fine.

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a very old friend of mine now passed on had mag tester and crazy looking unit to recharge mags he did for customers and mostly farmers........I remember him saying that if a mag is struck....... like a hit with a hammer type situation or dropped etc ,it can instantly lose its magnetism.........I kick myself for not learning more from him and possibly getting the now scrapped shop equipment

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Dave, that is a wonderful looking device. I wish you were closer so I could rent it! I might have to look around for some coils....

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