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seekertom 09-23-2012 09:06 PM

general question small engine ignition systems
hi, y'all! noobie here, but born loong ago, and still have a yen to learn new things.

latest project is trying to get my 17hp briggs engine/tractor back on line. two problems with it. 1st is no spark. probably magneto coil is shot, but i don't want to just replace it. that's no fun, right?

i'm hoping to rig up a vintage car coil and points system, but not sure about the ballpark where the spark ought to occur, with respect to position of the flywheel magnet.

the magnetron has two poles, so i'm wondering if it sparks twice, once for each passing of the magnet across one of the poles, or just once.

next, i'm wondering on a good starting point to place a flywheel bump to open the points. ought to be fairly simple to make the mount adjustable, once it's in the ballpark.

any idears where to begin?
thanks, st
ps 2nd problem i'll post separately so i don't confuse myself!:)

DrHicks 09-23-2012 09:47 PM

My personal experience, with having tried stuff like this before, is that you're probably better off just replacing the stock ignition parts. On most Briggs engines, the operative parts are under the flywheel. Most likely, you just have a condenser that's shorting out the system.

seekertom 09-23-2012 11:09 PM

ignition help
sounds like you're talking about a coil and points system. i've read that some engines used them, but in this case i'm not inclined to think mine is so. reason is, there's only one external wire connected to the coil, and i think it is the ground/stop engine circuit. the wire measures short to chassis ground when any of my safety items aren't right, like the clutch in, sitting down in the seat etc. to eliminate this possibility, i removed the wire from the coil. no spark.
so, at what point on the flywheel circumference is spark normally produced?
thanks, st

DrHicks 09-24-2012 07:26 AM

^ I'm really not smart enough to answer those questions. When we were doing our lawn-mowing service, I worked on all the stuff myself - including repairs like this. But I was usually in a hurry, and cussing it the whole time, rather than paying attention and learning.

I recall my old Kohler engines having points & a coil, but not any Briggs engines. My Briggs engines had something like in this picture. On some of the smaller engines, the coil/condenser was inside the flywheel.

Sorry I can't be of more help. :(

seekertom 09-24-2012 01:13 PM

ignition questions
appreciate the effort. we both have similar attitudes... i hate having to work on this stuff, but money is so tight i have to diy. my biggest problem is the way things go, i seldom get right into fixing what's broke. most of the time i end up having to fix 6 other things before i get to the part i was interested in. like my ryobi trimmer.. just needed a new pull cord, but after starting to get into it, i find the screws are so recessed i had to go buy a tool to get to them. that's the frustration i can do without.

the pic you showed is what ive got. therer are no parts under the flywheel itself, but the coil is located under the flywheel cover.

i suppose not being in control of things is the problem, and i'm hoping that using this new coil/points system puts me back into the drivers seat. i called briggs for the coil and they didn't even know my mod/ser nos are on paper labels on the flywheel cover, not embossed on the engine like they told me. plus, there's at least two different coils that are listed for this engine, and i just don't want the frustration of ordering the wrong one and all that entails. so i'll do it my way and at least know for sure what to expect.
thanks again!

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