J model ZEV problems

[exeric]

I've been having fits with my '16J. I've gone over, and over timing, carburetor, and detail issues to get it to run right. I can get it to run, but it starts hard, conks out, and is just plain miserable. After a sensible hiatus, I jumped back on it today and I think I have come to the conclusion that the magneto is weak. I rechecked the mag for point gap, and it's at .022", and like I said, the engine will run (just crappy). With the spark plugs out, and windmilling the motor with the starter, I get a very puny, somewhat intermittent spark.

Ed Strain (magneto guy) is just north of me in St. Pete so it's an easy trip to his shop. My question is; what should I ask him to do? I've had magnets re-magnetized before, but is it possible that the condenser is bad, or should the armature be rewound. Obviously, these are questions that only a magneto rebuilder could answer upon component analysis; but I'm just hoping someone can de-mystify some of the causes of a weak magneto. Thanks for any help; as you can see, these magnetos don't come off very easily.

[T. Cotten]

Eric!

Whats that brass thingy inside of your front manifold nut?

It passed a thorough bubble-test, right?

....Cotten

[exeric]

Tom, I had to re-sleeve, and true the manifold ('16 only) because it was very gouged, and irregular. I made PEEK seals to tightly fit the on-size manifold so it snugs up very well; and it did pass a bubble test, (unlike my '48FL). I'm still not convinced that my rebuild of the HX Schebler is good; but I have 2 similar HXs in (I believe) good shape, and they both performed about the same. . . Meaning, the engine will run with either carb, albeit, shabbily. I'm a lousy mechanic, and my diagnostic skills are poor at best. I have pursued the components I have a half-assed knowledge of, but magnetos are something I know I should not be messing with. I can set points, and that's it.

[whp]

Anybody who putzes with J's is a lousy mechanic that doesn't believe in the wonders of OHV and oil pumps.

I've been in the magneto zone for the last few months (I keep buying them...)

I usually have a friend hold the leads and then I spin it really fast. If they get mad then it works a little bit. After that I'll attach the lead to a fixed point and see what gap it starts to not spark at. I have a mag that'll spark 3/8" and one that'll do 1/4. If you're getting reliable spark at .125 I'd be comfortable running it again (and it might be the carb?).

If it doesn't spark every time without spinning it fast (faster than your hand) then the armature is probably bad. Usually the tar starts to seep out as it arcs all around inside. Marks Magnetos has a rewinder I think, that's where the local magneto guy here sends his to be rewound. If you want a diagnosis send your mag up here and I'll bring it to him and get his opinion if you want!

There's another tool I've seen that sees how much current (i think...) it takes to make the coil spark. If it's too high then it's toast.

[John Jackson]

Spark plugs should be checked under air pressure ..... similar to compression test....spark plug cleaning / machines , had this this feature.