JD LA105 crank no start

[freshman6969]

First post, but i appreciate you guys. i have a LA105 sitting in my garage right now that is my neighbors but trying to fix in lieu of using it my self for the farm. he used it once maybe twice a few weeks ago and had some issues parked it and borrowed another mower from his job. Im no mechanic but figured im out of work and have nothing better to do, said screw it ill take a look. I have a decent electrical knowlage and limited mechanical. tore the thing down cuz he said it had no spark, BOOM melted through plug wire going to the magneto, well i rigged and soldered a new lead on(is that a problem because of resistance issues?) looked around after still no start turns out there is a adjustment issue with the throttle spring its off. rigged up a bigger battery because his was dead. sprayed starter fluid and after about 10 cranks ill get a little something after playing with the throttle, pulled the carb off everyhing looked ok to me, the solonoid attached to the carb is functioning fine, clicks after key on. someone give me an idea of a direction here its bugging me not to hear this thing run lol also i did check the flywheel timing key its fine

 

[bertsmobile1]

Welcome.
The magneto is self energizing and has a hall effect trigger embedded in the coil
The one wire going to it is a ground wire and shorts out the coil causing the engine to stop , so it should not melt through , in fact it should never carry any current ever.
If it does the tne magneto will be toast as it will kill the trigger chip.
So your first step is to remove the wire , crank the engine & check for a spark
If there is none then the magneto is toast & need to be replaced.
Just sow are talking the same language, the magneto is on the outside of the flywheel and has one black wire attached to it.
The Alternator is under the flywheel & should have 2 wires hanging out of it .
The plug going tothe magneto usually has 2 wires on it
One will go to the magneto & as already stated is a ground wire and the other goes to the carburettor solenoid & is a power wire.
A picture of the offending plug would be very helpful.

 

[mac]

If you removed the coil when you took the engine apart, you could have the gap the coil and the flywheel wrong, that will cause no or weak spark. If the wire you repaired is under flywheel, that wire may charge the battery. If so, it could be the stator. If that’s the case, you’ll have to replace the stator.

 

[freshman6969]

IMG-20200425-124714

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IMG-20200425-124642

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This is the first thing i came across the magneto, you can see in the first pic that is the spark plug wire, second pic is the magneto and you can see where i repaired it, i had another brigs motor laying around so i chopped the plug off that and soldered it to the magneto. now i do get spark weather or not its correct idk because will impedance(because adding solder and a different plug end) change the spark timing? i also searched all over to find that exact magneto and i cant seem to find anything solid

 

[mac]

No, it won’t affect the timing, but if the plug wire is carbon filled, no amount of solder will repair it. You may be getting an arced spark from the coil to the plug wire. It would probably be weaker, and then the mower wouldn’t run right.

 

[bertsmobile1]

From the first photo I can see fresh scrapes on the fly wheel so the coil is too close
It should be gaped at .010" to .012" from the magnet .
As Mac posted earlier carbon filled fiberglass High Tension wires can not be soldered they get capped & fitted with crimp on terminals that puncture the insulation and contact the graphite.
Eventually the graphite looses contact with the terminal and the wire is bad so we replace them on our cars almost every service ( should have bought shares in that company ) .
You will need a new coil, they are fairly common .
It is impossible for the coil in the magneto to generate enough power to melt the HT lead, more likely it was rats , mice, or engine heat because the blower housing did not come off every year or to clean the fins .
As that coil is not trash, you can dig out the old wire where it is potted into the coil,
Some have a terminal that is simply a screw pointing out and you can screw in a new HT Lead then seal off the joint with some silicon and heat shrink as you did with the solder

 

[freshman6969]

From the first photo I can see fresh scrapes on the fly wheel so the coil is too close
It should be gaped at .010" to .012" from the magnet .
As Mac posted earlier carbon filled fiberglass High Tension wires can not be soldered they get capped & fitted with crimp on terminals that puncture the insulation and contact the graphite.
Eventually the graphite looses contact with the terminal and the wire is bad so we replace them on our cars almost every service ( should have bought shares in that company ) .
You will need a new coil, they are fairly common .
It is impossible for the coil in the magneto to generate enough power to melt the HT lead, more likely it was rats , mice, or engine heat because the blower housing did not come off every year or to clean the fins .
As that coil is not trash, you can dig out the old wire where it is potted into the coil,
Some have a terminal that is simply a screw pointing out and you can screw in a new HT Lead then seal off the joint with some silicon and heat shrink as you did with the solder

good to know its not total trash, that i can handle. and i will forsure gap it correctly. Im a car audio/remote start installer by trade. Decent mechanical knowledge but no expert lol. With that said i know THIS is not good https://ibb.co/b5sgsz6

pulled off the cover and it just flopped out, now the top one thats still together moves fine, the "Rod" on the other one does not move when hand turning the engine, the what im guessing is the piston?(one with the spring) does move. So what in the hell am i looking at here and is it salvageable?

 

[mac]

good to know its not total trash, that i can handle. and i will forsure gap it correctly. Im a car audio/remote start installer by trade. Decent mechanical knowledge but no expert lol. With that said i know THIS is not good https://ibb.co/b5sgsz6

pulled off the cover and it just flopped out, now the top one thats still together moves fine, the "Rod" on the other one does not move when hand turning the engine, the what im guessing is the piston?(one with the spring) does move. So what in the hell am i looking at here and is it salvageable?

What the hell is that last paragraph ?

 

[freshman6969]

What the hell is that last paragraph ?

IMG-20200425-180539

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i dont know why the image did not show

now that i read it over does seem a little funny huh lol

 

[bertsmobile1]

IMG-20200425-180539

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ibb.co

i dont know why the image did not show

now that i read it over does seem a little funny huh lol

Well that explains the no start
reinstall & regap both of the valves.
I use 0.004" set with the piston 1/4" ( approx) down the bore on firing stroke.
Note the nut is the adjuster & the grub screw ( Torx head ) is the lock .
They are quite fiddly to get right so don't worry if it takes you 1/2 dozen tries to get it right