R/R Test Reveals Reverse Flow??

[crash-harris]

I'm hoping that it at least gets me 12V to the coils if not get me some spark and get the bike running again.

Side covers will be made out of diamond plate aluminum and thick sheet steel, probably more boxy then stock, but as long as they keep things need and water out of them if I get caught in the rain. There were no side covers on the bike when my brother got it even, none at the bonyard here, but I've got the raw materials.

Thank you for all the help, I'll keep you all updated.

[crash-harris]

So which wire(s) am I drawing from for the signal?

The Coil Relay Mod Thread says that if I'm using a Bosch type relay it would be like this:

post 85- ground to the frame somwhere, or back to the battery negative post if close enough

post 86- kill switch...these are the orange wires that used to go to the coils, you will have to cut the wires to intercept them and route them to this post on the relay, they are orange and white on most GS's, run either one from the kill switch, or both of them if you wish, it makes no difference.

post 87- run this to both coils via the orange and white wires that already went to them, where you cut them off just wire them to this post. both of them, both wires go here, splice them together wherever you want, or run two wires to this post, whichever works best for you.

post 30- run this to the battery positive post.

I would just use a normal relay instead of the old truck relay, but I don't have any spade connectors large enough to crimp to the battery and starter cables.

[reddirtrider]

This one grounds from where it's bolted (on a truck) to the inside of the passenger side fender and they are ment to be beat on. Been through a lot of mud and over downed trees and some pretty rough terrain with it firmly bolted to the fender. So I plan to bolt it to the electronics plate tightly and not worry about it since they are made to take the vibration and abuse.

I'll try to wire it up this week

The plate that the electronics are bolted to on my GS is isolated from the frame with rubber grommets, apparently for vibration. Make sure your plate is ground or the relay will not have a path to ground.

[crash-harris]

I think I may have miss understood. This relay mod isn't ment to replace the solonoid between my positive cable and the starter is it? I did replace tat one with the truck solonoid and I am now getting slightly better readings and she'll still turn over.

[crash-harris]

Now I get it

I will probably get it done today or tomorrow then. Although replacing the relay for the stater did help me gain another volt and a half or so as well.

[crash-harris]

It's about 1.5 - 2 times the size of the stock Zook one. I successfully completed the relay mod and of course no spark (ignitor suspected), but I did gain a few more volts. Still under 12, but not by much, more like 11.6V/11.8V

As soon as I get a used igntior and this tank and R/R from 4rcFed my bike will be running

[crash-harris]

I think at that moment my battery was around 12.2V. I'm going to look for more connections to clean while I'm waiting on responses for the parts I need.

[crash-harris]

Some pictures of the mod(s) for you guys. Thumbnails are clickable.

This is more or less a temporary mounting location. I'm sure it won't fit there is the tank on.


Then the constant duty relay from an 8th gen Ford truck.

[crash-harris]

And how the poor bike looks at the moment...


The jumper cables laying there aren't for the charger, instead they are running to a lawnmower battery since the one bike battery I have can't hold a charge and it's sealed.

[pdqford]

You can test your bike by removing the tank and using your DMM (digital multimeter) with black lead on battery (-) and red lead on the supply lead to the coils (one on each coil). They are normally orange or orange/white(?)

Compare this voltage to the reading directly across your battery terminals to determine the loss you have.- JC

Sheeesh! Now I'm getting confused. I've been trying to follow various threads which discuss measuring the voltage drop in the coil primary circuit.

My DMM manual indicates that when measuring for voltage drop I should put the RED lead on the battery (+) terminal and the BLACK lead on the positive (+) terminal of the coil.

Additionally, it is my understanding that in order to measure a voltage drop, current must be flowing in the circuit. How does current flow in the circuit with the KOEO (Key On Engine Off) if the ignitior pulls the primary circuit to ground momentarily, only when the signal generator is spinning? And if one trys to read the voltage drop with the KOER (Key On Engine Running), the meter is going to be bouncing around between open circuit voltage and loaded voltage.

Could one of the electrical gurus give us a refresher course to be sure we are all using the correct method in determining the coil primary circuit voltage drop?

[reddirtrider]

Sheeesh! Now I'm getting confused. I've been trying to follow various threads which discuss measuring the voltage drop in the coil primary circuit.

My DMM manual indicates that when measuring for voltage drop I should put the RED lead on the battery (+) terminal and the BLACK lead on the positive (+) terminal of the coil.

Additionally, it is my understanding that in order to measure a voltage drop, current must be flowing in the circuit. How does current flow in the circuit with the KOEO (Key On Engine Off) if the ignitior pulls the primary circuit to ground momentarily, only when the signal generator is spinning? And if one trys to read the voltage drop with the KOER (Key On Engine Running), the meter is going to be bouncing around between open circuit voltage and loaded voltage.

Could one of the electrical gurus give us a refresher course to be sure we are all using the correct method in determining the coil primary circuit voltage drop?

I'll try to explain the coil circuit.

So, here's what's going on. When the ignitor fires for a specific set of coils, it grounds the low side allowing current to flow through the coil primary. This current is coupled to the secondary side and there is a large voltage gain defined by the inductance relationship between the primary and secondary side set by the turns ratio. The voltage developed on the secondary side is applied to the spark plug and when it reaches a level high enough to bridge this gap with an arc, the plug fires.

The current is pulsed, not constant. Thus, the voltage drop is a time derivative of the current since we are dealing with inductors. What this means is that the current is going to be very much smaller that what you would expect if you divided the voltage applied by the dc resistance on the primary side. Specifically v=L*di/dt or i=integral of v/L

The voltage drop leading to each coil is a pulse defined by the current. Depending on the meter it's going to read an average of the voltage (a guess - I'm not a meter expert and I don't have time too look it up now, I'm working on a presentation for Monday). So, yes your bike should be running.

[pdqford]

So, here's what's going on. When the ignitor fires for a specific set of coils, it grounds the low side allowing current to flow through the coil primary.

So far, so good. That's when the coil primary circuit begins to flow current and that is when I want to measure the voltage drop, right?

The current is pulsed, not constant.

Right. The ignitor turns the current on by pulling the low side of the coil to ground long enough to saturate the primary windings and then turns the current off by releasing the ground (which induces a high voltage in the secondary).

The voltage drop leading to each coil is a pulse defined by the current. Depending on the meter it's going to read an average of the voltage (a guess - I'm not a meter expert ....

Yes, as I understand it some meters read the average voltage, and an RMS meter reads the Root Mean Square of the voltage.

So, yes your bike should be running.

Okay, so we should put the red lead of the DMM on the battery (+) terminal and the black lead on the primary (+) terminal of the coil, and use the min/max feature of the DMM to capture the lowest voltage drop during the current on (pulse) periods? (That's not a statement, its meant as a question.

[pdqford]

When I tested mine the first time, I disconnected my coils and tested the orange/white (IIRC) leads. But mine were aftermarket with spade connectors and easy to do this.- JC

See, that's what is confusing me. If the coil primary is disconnected there is no current flowing through the coil primary feed harness and the meter would just read OCV (Open Circuit Voltage).

So leave the engine off, key on (some drop in battery voltage can normally be expected), and test the battery across the terminals and compare it to the volts being supplied to each coil.

Can you elaborate on which meter lead was connected to where when you tested your coil feed voltage drop?

[crash-harris]

Nice pics, thanks! PO (previous owner) liked red, eh?

Are you sure the relay placement will clear the tank? You might want to do a test fit before you get too far just to be sure.

That's a decent result for the coil relay mod, but you should be getting less of a drop. Be sure you are checking the battery voltage across the terminals with the key turned on and use that for comparison to the voltage at the coils.

There's almost nothing in the circuit to the coils, so it should be very close to the same as your battery.

Looks like you have quite a project on your hands. All the better when it's running!

- JC

I was reading the voltage with the key on, I think I may need to look at my coils ground connection since I left the stock wiring there for the ground. As for the relay, I don't think it will clear the tank, just putting it there until I get the tank so I can figure out a more permanant home for the relay.

Both my brother and the guy he bought it from rattle canned the bike and got over spray EVERYWHERE 1 random coat of black primer and 3 random coats of crap red...

[reddirtrider]

Okay, so we should put the red lead of the DMM on the battery (+) terminal and the black lead on the primary (+) terminal of the coil, and use the min/max feature of the DMM to capture the lowest voltage drop during the current on (pulse) periods? (That's not a statement, its meant as a question.

That should give you the voltage drop across the wiring to the coils.