open loop to coil ??

[markmoss77]

So this is going to get a lil technical so get a cup of coffee and follow along . After replacing the plugs in my 82 GS850G I noticed I still had a miss this was a problem I had dealt with before with a fouled plug , so I assumed the new plugs would resolve this matter , wrong , so now I broke out the handy test light and began testing the leads to the coils themselves . The right coil which I assume woould spark cylinders two and three have 12v positive goin in to both sides , the left coil which I assume sparks cylinders one and four has 12v to one side , whne i test the right side the coil grounds and the bike dies? Not exactly sure how a points set up works to send signal to the coils but I can tell something isnt right , anybody encountered this before?Is there a by-pass to this , thought about switching the coils to see if the miss moves to another cylinder , if so we would have a coil problem correct? and if the miss remains on the same cylinder it would be between the points and the coils ? correct . Any knowledge would be helpful , Thanks again GS !!!

[rustybronco]

The right coil which I assume woould spark cylinders two and three have 12v positive goin in to both sides,

Wrong, you dont have 12 volts going into both sides. you have 12volts going into and coming out of the coil (voltage going through it).

Not exactly sure how a points set up works to send signal to the coils but I can tell something isn't right , anybody encountered this before?Is there a by-pass to this , thought about switching the coils to see if the miss moves to another cylinder , if so we would have a coil problem correct? and if the miss remains on the same cylinder it would be between the points and the coils

Your bike doesn't have points. it has an electronic ignition system. the way it works is, current is sent to the coils and the igniter grounds the coil. when the pickup coil mounted under the right side cover sends a signal to the igniter which disconnects (opens) the ground side of the coil, the magnetic field in the coil collapses and you see the result as a voltage (spark) coming out the HV winding of the coil.

[Tom R]

So you should see a voltage on both sides of the coil.

[rustybronco]

So you should see a voltage on both sides of the coil.

Until the igniter grounds it; the you will see 12 volts on one side and close to 0 Volts on the other side.

[Tom R]

Until the igniter grounds it; the you will see 12 volts on one side and close to 0 Volts on the other side.

If you're grounding to the frame, you're upstream of the igniter.

[rustybronco]

If you're grounding to the frame, you're upstream of the igniter.

Huh??..... what are you trying to say?

[Tom R]

You have a constant feed of, hopefully, 12v to the primary winding of the coil - it's only when this current is cut off that the magnetic field in the coil collapses and induces a spark. If you grounded your coil, it would never spark - his test light is the ground for the primary winding in this case and will let the current flow through it.

[rustybronco]

his test light is the ground for the primary winding in this case and will let the current flow through it.

That's assuming the test light will flow enough current to interrupt the function of coil grounding by the igniter.

I don't have any idea if it does or doesn't.

[Tom R]

That's assuming the test light will flow enough current to interrupt the function of coil grounding by the igniter.

I don't have any idea if it does or doesn't.

It doesn't matter. both terminals on the coil are either end of the primary winding. If you have 12V on one side, you should have some voltage on the other, depending on the resistance of the coil. The igniter controls the opening and closing of the circuit.

[BassCliff]

Hi,

Start here:

Testing The Ignition System

Then see the rest of the information on this page:

*Electrical Odds and Ends*

Thank you for your indulgence,

BassCliff

[markmoss77]

succeessssss!!!

So after a lil research on Basscliffs site and some awesome feedback from you guys , I tried a simple test , I switched the 12v in/signal wire to the coil with the misfire , Voila~! cured , running on all 4 again ., apparently some jackwagon got the wiring a lil confused , and had the in on the out and etc , but whatever , its cured , ever heard of a 82 GS850G running 4 coils? I have 2 more leads that we cant figure if they are horn wires , as my horns are MIA , or if there may have been 4 coils . not an expert , just curious

[BlackStar]

IIRC my horn wires can out of the harness near or with the coil wires. Are they hot with the IGN on, do they become hot when you poke the horn button?

[koolaid_kid]

For each horn - one wire is hot (12V) when the key is on. The other wire is open (infinite resistance) until the horn button is pressed. The horn button grounds the circuit and causes the horn to sound.