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Old 03-13-2013, 10:54 AM   post #1 of 8
ribertgropius
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Default Satoh 650G melted ignition wires

Yesterday I came home after a torrential rainfall at my property in Northern VA to find some large ruts in my 1/2 mile long steeply sloping gravel driveway. Knowing I had an hour before I had to take my daughter to an appointment, I thought I had enough time to drag the blade over the large ones at the mouth. All was good until on the way back up the slope, I ran out of gas! Ok, so i was an idiot. No big deal, I was able to push the tractor to one side and walk up the rest of the way and still be on time, and get gas along the way.

Two hours later, I walked down to the tractor, gas can and funnel in hand, and noticed I had left the ignition switch on in my haste to leave earlier. Still no big deal, right? Filled the tank, climbed onto the seat , turned it over...won't start. Opened the hood and...what was left of my low tension wire leading from the coil to the distributor terminal was just sort of dangling like a thread, the insulation melted off it completely. I am an idiot, but no big deal, right?

I assume that what must have happened is the engine stopped with the points closed, and it was trying to spark away for two hours. I walked back up the slope, had to go to the barn for some twisted strand 18 ga wire, crimped on two terminal eyelets, grabbed a couple of ignition wrenches, and headed back down the slope with a lantern, reminding myself that I was an idiot, but NO BiG DEAL.

I replaced the melted wire, climbed on the tractor....still won't start. Popped off the dstributor cap, pulled the rotor and dust cover, turned it over, and saw intermittent sparking, and not where it should be at the points. The insulation on the wire from the points to the distributor terminal appeared to have melted and must have been shorting. I pulled the wire up clear to verify, see sparks EVERYWHERE when I turned the key, and noticed that if I leave the ignition on, the points and wire lead get RED HOT. Must be a fair amount of resistance there but all I want to do for now is get it up the drive; I should be able to tape the wire for now, no big deal, right?

Head back up the slope, find my electrical tape, come back down, have to loosen the wire where it slips under the terminal screw, straighten the wire, tape it, reinstall it under the screw, check it before putting the dust cap, rotor, and distributor cap back, see the spark at the points but not great, tuck the taped wire, which has now become pretty stiff and feels a little flimsy at the ends, back in place, put the covers and rotor back, turn it over......NO START.

No big deal, right?

Open the cap up, no spark, can't see an obvious wire break, re-tape it, STILL NO SPARK. It's been two hours...almost 10:00pm; fingers are cold, know I am going to drop one of those little nuts if am not careful...haven't had dinner and can't remember lunch.... I gave up. I think that was the only intelligent thing I did all night. Apparently my stupidity had become A BIG DEAL!

So this morning as I drove past my lovely tractor I had to laugh at myself. Sometimes "things" happen. My guess is I burned the points up when i left the ignition on, and the resulting resistance caused the melted wires. The points were new this year but oh well, I will have to rplace them since their lead wire is quite literally "toast". Of course no one stocks points for a Satoh 650G, so I will have to order them at a store or on line and wait a couple of days. Maybe that is a good thing.

And as I recall, I had a heck of a time installing them earlier this year, trying to make sure the end of the lead wire from the points didn't short against the case and/or the dust cap of the tiny distributor. On that occasion I managed to overtighten the terminal screw and break it, and then had to find and modify a replacement screw. But that is another story....NO BIG DEAL!

Hope this tale of woe reassures others like myself that sometimes things just don't go the way one expects them to go. The good news: no blood lost, no parts lost, no permanent damage, other than to my pride; and being reminded of my humility is not necessarily a bad thing.

Oh...by the way...does my theory of why the wires melted make sense?

Robert


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Last edited by ribertgropius; 03-13-2013 at 11:13 AM.
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Old 03-14-2013, 10:08 PM   post #2 of 8
2jappers
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Default Re: Satoh 650G melted ignition wires

I'm thinking the coil primary winding may have burnt up and shorted out when the ignition was left on(with points closed) Coil primary resistance for a 12v coil meant for use without ballast resistor should be around 3-4 ohms.if coil is shorted,make sure replacement is one meant for use without a ballast resistor.
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Old 03-16-2013, 12:12 AM   post #3 of 8
ribertgropius
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Default Re: Satoh 650G melted ignition wires

Quote:
Originally Posted by 2jappers View Post
I'm thinking the coil primary winding may have burnt up and shorted out when the ignition was left on(with points closed) Coil primary resistance for a 12v coil meant for use without ballast resistor should be around 3-4 ohms.if coil is shorted,make sure replacement is one meant for use without a ballast resistor.
LOL I think you hit the nail on the head! I went back out with a fresh start to see if I could figure out what was wrong. I first pulled the points to see how burnt they were: the entire flat surface on both sides was quite discolored, and I checked the resistance across them and it was definitely a number, so I took a nail file to clean them up, and checked the resistance again to confirm it was considerably better. While not perfect, I figured it would be enough to get it started.

I also noticed the wire between the points and the inside terminal conneting blade, which I taped before, was really shot. So, I had saved the points that I had replaced in the spring of last year, and stole the wire from that set (which had even greater resistance) to replace my burnt up wire. Double checked the resistance to make sure everything was OK, and went back out to install it. Still no spark.

So then I took my ohm meter and made sure I had 12v going into the coil when the ignition was on, which I did. I then checked to make sure I had continuity between the negative terminal of the coil and the points, which tested fine. And then...I tested for continuity across the coil....NONE. Yes, the coil was fried.

So looking on line, I saw listings for the Satoh 650g to use the Napa IC70 coil WITH an Napa ICR 23 resistor ballast. I bought them, but noticed that the coil I removed was a Standard 806, marked "use with electronic ignition." As you implied in your post, there was no ballast resistor in the circuit before, and I am assuming that the Standard coil did not require one.

So now I have to make a decisiion to make:
  1. Put in the NAPA IC70 coil along with the Ballast Resistor ICR23, after I find a plae to mount the resistor, or....
  2. Return what I bought and get a coil that doesn't need an external resistor.
.

The Napa IC70 was about $30, and the coil ballast resister was about $5.50; it may be cheaper to just get a more common universal coil that does not require a ballast resistor, but how do I know what to get? Any recommendation?

Regardless, your trouble shooting was dead on: The coil shorted out, was sending too much power through the coil wire and points so that it not only melted the wires, it burnt the points as well. I replaced the coil wire with an 18 Ga wire I have from another project, and I will pick up new points and condensor tomorrow morning to complete the job.

Thanks for the response.

Robert
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Old 03-16-2013, 12:35 AM   post #4 of 8
2jappers
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Default Re: Satoh 650G melted ignition wires

The coil you removed,meant for electronic ignition,was very wrong for use with points-ohms too low,will overheat and burnup points and cause poor ignition performance.You could use the coil you bought with the ballast resistor-in most circuits where a ballast resistor is used,the ballast resistor is bypassed during cranking so that a strong spark is delivered while the starter motor pulls the volts to the coil down-some starter solenoids have a terminal on them that connects to the coil + for this purpose.Coils that do not need a ballast resistor are common in tractors-farm supply stores may have one if Napa does not.
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Old 03-16-2013, 01:13 AM   post #5 of 8
ribertgropius
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Default Re: Satoh 650G melted ignition wires

thanks! I wondered about the old coil whether it was correct or not. I have previously had problems with the points seeming to close on their own; perhaps this was actually a sign of them burning up from too much current.

I will see if NAPA will let me exchange this coil since I just bought it this evening and have not installed it, for a NAPA IC14SB coil, which has an internal resistor in it. If not, I will find a place for the coil resistor and wire it on the positive side of the coil.


One other question: what gauge wire do you recommend for connecting the coild to the distributor? It looked like what was there was 18Ga.

Robert
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Old 03-16-2013, 02:01 AM   post #6 of 8
2jappers
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Default Re: Satoh 650G melted ignition wires

18GA. will be fine
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Old 03-16-2013, 09:07 PM   post #7 of 8
ribertgropius
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Default Re: Satoh 650G melted ignition wires

I was able to return the NAPA IC70 coil and ICR23 ballast resistor and find an equivalent to the NAPA IC14(sb), which is the IC70 but with an internal resistor, at Autozone: LU800. Apparently it is the same coil that is used for early 70's VW Beetles. And it was less than $17, (compared to the $36 for the IC70 and ICR 23 ballast resistor) , and they had it in stock. I bought new points and condensor as well just to make sure everything was ok.

Hopefully will have it up and running tomorrow. Thanks for the advice.

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Old 03-17-2013, 11:17 PM   post #8 of 8
ribertgropius
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Default Re: Satoh 650G melted ignition wires

Success!

And a few observations:
  • Working in that distributor is very tight. I had to check and re-check connections to make sure that nothing was shorting out. I highly recommend using a continuity meter to confirm you have everything in place without shorts.
  • When I was checking for shorts with a continuity meter, I was a bit confused by the fact that there was continuity with negative when the ignition switch was turned off, on both sides of the circuit: With all the wires in place, I would connect the meter to the distributor post, and touch the distributor, and it would show continuity, even when the points were open. However, when the ignition switch was turned on, it gave me 12v. If I disconnected the wire from the coil, then there was not continuity, so the continuity to negative must have been occuring through the starter switch when in the OFF position. I assume that when you turn the ignition switch off it must connect to ground, which is why I had the continuity on both sides. When you turn it on, it must connect to positive.
  • Before I put the dust cap back on, I made sure I saw a spark across the points when I turned the engine over. Then, from previous experience, I made SURE that the dust cap tabs were nowhere near the terminal screw penetrating the distributor; I had a problem earlier in the year that one of those tabs was directly over the screw and somehow was causing a short.

She seems to be running fine. I replaced the points, condensor, and the wire from the new coil to the distributor. The old points were pretty burnt, and while I was able to file them smooth(er), probably not worth keeping. The condensor was probably fine, but since I was replacing everything else, thought I might as well not take a chance. Now I really should check the timing, and I will also hook up a dwell meter to make sure I have the points set correctly at .018.

Thanks for the advice.

Robert
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Last edited by ribertgropius; 03-18-2013 at 12:27 AM.
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