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A Little Off Plumb
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In researching information for electronic ignition while working on my TRA10D engine I came across some information on the electronic ignition that was used on the Wisconsin Engine Models TRA-12D and S14D. Since there is not a lot of information on these units and the only way to trouble shoot them that I have found is by replacing them if everything else tests ok I thought I would share what I found. There is a first and second design - the first design was a one piece where everything is mounted on the stator and located under the flywheel. The second design was a two piece unit where the stator with the three coils was located under the flywheel and a separate small box was located on the engine shroud. According to the information sheets there are three coils on the stator - one acts as a trigger to supply a small amount of current to trigger a SCR. I believe the other two coils that the magnets located on the inside of the flywheel would pass over first as the engine rotates are charge coils designed to produce AC current that is rectified to DC current as it passes through a diode and charges a capacitor. I have a TRA12D with a broken camshaft that I got as a basket case with one of my tractors and it had the first design one piece stator which I removed and put away for safe keeping when I set the engine on a shelf. The place where I put it was so safe I couldn't find it when I went looking for it a few years ago but I finally stumbled across it a little while ago so I took a few pictures of it. Since it is still sealed and I assume it still works I don't really want to try and take it apart to see what magic parts were actually used in it.

I found pictures on a web site that shows what the poles looked like and one of the coils. In this case the owner converted it over to electronic ignition using a hall effect switch mounted on one of the poles. I think it is actually mounted on a charge pole rather than the one that triggers the original circuit but for his application he states that it works ok. He appears to be using it to turn on a power transistor to fire an ignition coil using battery ignition.

Here is a link to the web site where I found pictures of the stator with the coils removed

http://www.dansworkshop.com/2008/03/homebuilt-solid-state-ignition-module/

Thought I would share the information as it may help someone
 

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Good info! Ironically I also have a TRA-12D with a broken camshaft. I wonder if that might have been a weak spot of that particular model Wisconsin. After removing all the "guts" I put the crankshaft, side plate and flywheel back in place. The ignition system produces a nice snappy blue spark when spinning the flywheel. It is the first version with everything under the flywheel and a single wire coming out to feed the coil. I have everything tucked away in case I ever find a TRA-12D that needs ignition parts.
 

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I had one S14D engine in a tractor an will never have another. Guess they are great if they run but if they don't - - - ? Mine went down the road at a loss $ wise but a big win as far as I was concerned. The 4 or 5 Wisconsin engines I have are points ignition and run great.
 

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A Little Off Plumb
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Discussion Starter · #4 ·
Good info! Ironically I also have a TRA-12D with a broken camshaft. I wonder if that might have been a weak spot of that particular model Wisconsin. After removing all the "guts" I put the crankshaft, side plate and flywheel back in place. The ignition system produces a nice snappy blue spark when spinning the flywheel. It is the first version with everything under the flywheel and a single wire coming out to feed the coil. I have everything tucked away in case I ever find a TRA-12D that needs ignition parts.
If memory serves me correctly the camshaft is the same as what was used in the TRA-10D - not sure if it is still available new or not. I have seen a few broken in the TRA-10D's as well so as you say they may have been a weak link since they are hollow where the compression release fits in and I think that area is where this one is broken.

I had one S14D engine in a tractor an will never have another. Guess they are great if they run but if they don't - - - ? Mine went down the road at a loss $ wise but a big win as far as I was concerned. The 4 or 5 Wisconsin engines I have are points ignition and run great.
Like everything else great when they are working but no fun when they are not. If I could find one that was bad I would be interested in taking it apart to see if the components could be identified and modern equivalents found. It would be easy enough to rewind the coils once the magnet wire size was identified. I would assume the majority of the ones that failed either had a bad capacitor or SCR which I would think should be fairly easy to replace if they weren't buried in epoxy. Points are ok but I don't know if the TRA-12D or S14D had provisions to convert them back to a points set up and I imagine the coil would have to be changed or a ballast resistor added to convert things to battery ignition.
 

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Points are ok but I don't know if the TRA-12D or S14D had provisions to convert them back to a points set up and I imagine the coil would have to be changed or a ballast resistor added to convert things to battery ignition.
The S14D block does not have provisions for the points. The S12D block had a spot recessed cast into the block for the point system. Overnight Solutions has/had a replacement for the troublesome S14D ignition system. I've had one on my tractor for close to 20 years w/out issues.
 

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DR. Bolens
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As I recently learned looking though old sheets , the TRA12D & S14D did see a limited production run of points engines , they were only certain spec numbers but some of these still do exist out there , one guy had one in his Bolens though he was crazy until he sent photos , and found years later actual paperwork to corroborate the story . Rare but there are some out there with points
 

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Good info! Ironically I also have a TRA-12D with a broken camshaft. I wonder if that might have been a weak spot of that particular model Wisconsin. After removing all the "guts" I put the crankshaft, side plate and flywheel back in place. The ignition system produces a nice snappy blue spark when spinning the flywheel. It is the first version with everything under the flywheel and a single wire coming out to feed the coil. I have everything tucked away in case I ever find a TRA-12D that needs ignition parts.
I would be interested in the tra12d mag if you still have it.....bolenwild
 

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Great info on the Solid State ignition. After damaging mine on my TRA-12D, I attempted to take apart the module to identify the parts inside. Unfortunately it is so well encased in epoxy, it was essentially impossible. The only epoxy removal technique that worked was to heat with a torch until the epoxy degraded and then attempt to scrape away the epoxy without damaging the parts underneath. I've attached some pictures if anyone is curious. I started a wiring circuit diagram of the internals but had to give up.
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Personally, those S14D engines are not worth wasting $.10 on or any time. They simply are not worth the headache.
 

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I have one of them in a 1477. Spent a fair amount of $ rebuilding it several years ago. Bored the jug, new piston, rings, new guides and valves, all new bearings, seals etc. It has the single wire stator feeding the coil. Had a #ell of a time with it a couple of winters ago when it would randomly decide to not start when I needed it to plow snow. Finally with some good advise from forum members I found that the coil had started to go bad. Took one from a broken TRA-12D and switching to a Champ plug instead of an Autolite and it has been fairly well behaved since. Knowing now what I didn't know then, I should have just repowered the tractor with a V-twin of 16 to 20 hp. Instead of rebuilding the Wisconsin. Just sayin'. Yeah , I know, that ruins the originality of the tractor and renders it basically worthless as far as some of the tractor lovers are concerned. Maybe some day? Maybe not. For now it starts and runs, does what I need it to do.
 
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