Oem coil vs aftermarket coils

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There are some passible AM modules but it is a crap shoot. A friend has one we put on his Jonsered last summer and it is still working well, when one went out on one of my Stihls it got replaced with OEM it was on a 028, 33 years of run time on the old unit so not a bad record, not like they go out ever 4 - 5 years.
 
Oh no, I have no thought of successfully "disassembling" a saw ignition module. But I'm not sure that having electrical "specifications" for chainsaw ignitions is a waste of time. Indeed, the total impracticality of getting "into" a module is one reason I vote for disclosure. It is possible to "observe" chainsaw ignition by taking the chain off, putting the bar in a vise, attaching a pickup to the plug wire and a "degree wheel" (of various forms) to the open clutch side. Depending on the pickup it is also possible to get a useful measure of secondary voltage, etc.

The motives are several: 1. Fixing individual saws. (Some module is brand new, put on a saw, and its sorta starts, but you've got to pull super fast at the cord to get it to go. Is it not making spark until it gets spun faster than usual pull? What does it owe you at what speed?) 2. Developing a kind of "community" consensus and understanding. One set of saws shows ... 18kv on the plug wire (at pull on the cord), another is characteristically 12 kv -- and has a tendency to foul. Worth knowing -- and even maybe having an opinion about. 3. There are people pushing ignition advance -- which is fine -- but they are a bit too much at the mercy of "cut and try" (and somewhat "get lucky") methods. Figuring out that Q degrees of advance is good, and Q+ really isn't -- is worth it to them.

So. No worries. We've all got a lot of ignition modules that do a lot of workiing -- and which we might as well just not worry about. But, I do continue to think that knowing about modules, rather than not knowing is, in its own way, gooder.
I agree, it would be great to get some AM coil specs when trying to find a replacement one for obsolete saws. Just need 2 timing specs, one at top rpm and one at starting rpm. As all ignition units have a minimum required rpm before they will produce a spark, that would be good too. Often someone will check the spark by pulling the plug and holding it against the cylinder while whizzing the engine over real fast as there is no compression, then finds when the plug is in, and engine harder to pull over, the engine just isn't turning fast enough now to produce a spark.
 
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