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Coil swap 650 to 850?

  • Thread starter Thread starter GSNewbie
  • Start date Start date
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GSNewbie

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I tested my coils (79 GS 850G) and am getting nothing out of them. Sparks at the points and juice to the coils, just nothing coming through them. Can I swap my 650 coils (80 GS650G) for the purposes of seeing if it will run on them?:-s
 
Thanks!
Granted the coils are bad as indicated, what is the best replacement? I know a little on dyna but $ 450-500 for a complete ignition seems steep...
 
Both 850 coils check out bad ?- seems unlikely unless they got cooked. Have you measured the primary and secondary resistance of these coils with your multimeter? primary like 3 to 5 ohms, secondary (caps removed) maybe 12 kohms. Are they leaking hazmat?
 
GSNewbie said:
I know a little on dyna but $ 450-500 for a complete ignition seems steep...
Click to expand...

Yeah. I doubt also that both coils would croak at the same time. Have you checked all the wiring to them? Also, I can't see ignition replacements costing anywhere near that.
 
Hi,

If your coils are bad (unlikely, but possible) the most popular replacement are the green 3 ohm Dynatek coils. Although, with a points system you probably want the black 5 ohm coils instead. Z1 has them for a pretty good price. If it's just the coils that are bad there shouldn't be a need to replace the whole ignition, just the coils. But test thoroughly before you start spending money.

3 ohm coils: http://www.z1enterprises.com/detail.aspx?ID=210

5 ohm coils: http://www.z1enterprises.com/detail.aspx?ID=1307


Thank you for your indulgence,

BassCliff
 
If you determine your coils are bad, PM me as I have a set (both 4 ohm primary) off a 82 850- these have the molded in wires with bullet connectors, unlike the 650 coils with spade connectors.
 
So I did the ohm test for each coil (between plug caps on each coil individually). Ohm meter set to 200k as anything below it just registered "1". Coil 1-4 measured 512k and coil 2-3 measured 30.2

What exactly does this mean? I saw the figure of 20-30,000 ohm being the figure I need...

They do have lots of dirt on them but I don't think it's hazmat?

And they may have been cooked (as in fire). The plastic manifolds where they dump from the carbs into the airbox have been melted. Nothing else looks burned. I will need a new airbox or manifolds.
 
Last edited:
Coil 2-3 ( 30 kohms ) seems about right-plug cap to plug cap. Best to remove plug caps and check wire to wire-you should get about 12kohms. 1-4 coil could have bad plug cap or poor connection.
 
Pulled the caps off and tested 1/4 coil with 11.9 ohms. Sounds bad. Why wouldn't I get at least a little spark from 2/3? Any suggestions?
 
GSNewbie said:
Pulled the caps off and tested 1/4 coil with 11.9 ohms. Sounds bad. Why wouldn't I get at least a little spark from 2/3? Any suggestions?
Click to expand...
11.9 ohms??? I think your meter is reading 11.9 kohms-wrong scale on meter?
Since you have points, are they opening and closing? are they connected to coils?
 
No luck yet

No luck yet

The points are opening and closing when I turn the crank (and sparking).
I tested the coils after cutting off 1/2 inch on each spark plug wire. Ohm meter set to 20k(I can't get readings but "1" on any other setting).
2/3 is now 11.29
1/4 is 12.17
I do now have 12.5V going to the coils.
I tried putting power direct to top of the cap and testing the plug connector inside the cap and couldn't even get the test light to light (strange).

I added a ground wire from the frame to the battery box to see if that made a difference.

I've been reading the manual like crazy. I've tried testing the wires from the points to the coils, but haven't figured out how to do this. I tried a test light and nothing. I'm not sure what to do next?
 
Last edited:
GSNewbie said:
I've been reading the manual like crazy. I've tried testing the wires from the points to the coils, but haven't figured out how to do this. I tried a test light and nothing. I'm not sure what to do next?
Click to expand...

Take your test light and probe it into the non orange/white wire (the ground wire) at the coil connector while plugged in. I was able to put it into the back side of the connector so as not to damage insulation. Clip the wire of the light to a good ground. Turn your key on. Turn your engine by hand or flick a small screwdriver past the pick-up. If the light comes on your wiring is good. Do this for both coil connectors. If good all around your ignition is working properly and there is something up with coils/plugs/wires.

You have points? I thought it would be signal generator and ignitor for your year.
 
Thanks! That was easy. I stuck the test light in the black/yellow and white wires and then touched the starter on each was getting signal. Looks like a coil issue (which has been my assumption all along but it's good to check each item off).
I have the 650G sitting here so I guess I can strip them off and try 'em as it's only time doing it...
 
Okay. I didn't see your reply before my last post. So far so good. The test light should have flickered on and off while you bumped the starter. Did it?

Are you checking for spark by laying the plugs on the head? If the plugs are blackened at all they might be insulated by the buildup and not grounding on the head when testing. You should have at least a faint spark. You can hear it even if you're not able to see it well.

Have you pulled the plug caps off to see if there's any corrosion on the wire? Snip off a bit to expose fresh wire if so. I'm wondering if when you tested the coil resistance with the meter that the leads reached to a clean spot. Make sure there's no corrosion in the plug cap or on the spark plug.
 
Gonna try a new set of plugs...

Gonna try a new set of plugs...

Today I put the GS650 coils on the GS850.
I just put a plug for another bike in the cap and got some spark. I think I'll go get a full set of plugs and try again.

I couldn't get any spark through the old plugs.


I did see the lights go on and off when testing wires coming from the points (white and black) with the test light.
They are getting 10.09vdc on each cycle on the wires coming from the points.

Are you checking for spark by laying the plugs on the head?
Yes. Also tried the spark indicator light I have for checking spark through the wires.

If the plugs are blackened at all they might be insulated by the buildup and not grounding on the head when testing. You should have at least a faint spark. You can hear it even if you're not able to see it well. Could be an issue but doesn't seem to be

Have you pulled the plug caps off to see if there's any corrosion on the wire? Snip off a bit to expose fresh wire if so. I'm wondering if when you tested the coil resistance with the meter that the leads reached to a clean spot. Make sure there's no corrosion in the plug cap or on the spark plug.

This was in my last post. I removed 1/2 inch of wire and re installed the caps.
 
GSNewbie said:
Today I put the GS650 coils on the GS850.
I just put a plug for another bike in the cap and got some spark.
Click to expand...

Sweet. Let's hope new plugs solve the problem. It is still unlikely that both coils have died.


GSNewbie said:
This was in my last post. I removed 1/2 inch of wire and re installed the caps.
Click to expand...

Oops. missed that. Okay. At least it's narrowed down to the coils/plugs/wires. What's nice about the points ignition is it's direct to coils instead of through ignitor. One less thing to have fail.

Keep us posted and good luck.
 
WooHoo!

WooHoo!

THANKS!!

It was the plugs!!!
(or at least that was the last straw)!
I ran the bike tonight and am surprised at how smooth it is running... I am running techron through the fuel and we'll see if I rebuild the carbs or just look for the head and cv carbs.

If I can find carbs, head, airbox boots for the right price, they sound like the way to go...:)


Gonna ride it tomorrow and see if I can shake some bugs loose. It was last plated in 2009 but I'm betting these carbs haven't been rebuilt proper...:rolleyes:

I'd rather get the hp and only mess with fixing carbs and buying one set of airbox boots etc.
 
Last edited:
That's great news!! :D
Did you leave the 650 coils on? Are the ones from the 850 shot?

A nice ride on a Monday sounds good. If this Tropical Storm would give me a couple of hours without rain/wind I'd burn off some petrol too.
 
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