Anyone seen this behaviour before?

[Guest]

I'd love to do a search on this but I can't even think of how to look for it.

I'm trying to troubleshoot about a 1.5 to 2 volt loss in my wiring harness and in addition there appears to be no spark.

So, last night I had everything off the harness and I progressively plugged things in until I found the voltage drop.

Turned out it first showed up with the right coil. With the left coil connected it was fine. Both coils connected still shows the drop.

However, I went to double check it, and the voltage drop then occurred with the left coil, not the right coil. As in, left coil connected, loss of voltage, right coil connected, voltage fine. Both coils connected the drop's still there again.

So, this behaviour seems to swap between the coils...

Anyway, I realised afterwards the only thing I didn't try doing was disconnecting the igniter with the coils connected.

So, while I'm waiting to get some time to go and try that, I'm wondering if anyone else has seen this behaviour before? Has me baffled unless of course the igniter itself is doing it because that's where the coil primaries connect to.

It's an '82 450E.

 

[posplayr]

I'd love to do a search on this but I can't even think of how to look for it.

I'm trying to troubleshoot about a 1.5 to 2 volt loss in my wiring harness and in addition there appears to be no spark.

So, last night I had everything off the harness and I progressively plugged things in until I found the voltage drop.

Turned out it first showed up with the right coil. With the left coil connected it was fine. Both coils connected still shows the drop.

However, I went to double check it, and the voltage drop then occurred with the left coil, not the right coil. As in, left coil connected, loss of voltage, right coil connected, voltage fine. Both coils connected the drop's still there again.

So, this behaviour seems to swap between the coils...

Anyway, I realised afterwards the only thing I didn't try doing was disconnecting the igniter with the coils connected.

So, while I'm waiting to get some time to go and try that, I'm wondering if anyone else has seen this behaviour before? Has me baffled unless of course the igniter itself is doing it because that's where the coil primaries connect to.

It's an '82 450E.

The ignitor alternately shorts the 1-4 coil and then the 2-3 coil to ground using a solid state device. Which ever one is shorting will pull the voltage down.

The power to both 1-4 and 2-3 comes from exatly the same place ; there is a crimp in the harness right under the gas tank.

The drop comes from that crimp or somewhere further upstream at the kill switch->fuse box->ignition switch->R/R "T"-> Battery

If you look at my link for "yet another coil relay mod" I have mapped it out

 

[Steve]

How much of a drop are you seeing, and what is your power source?

Coils will draw 4-5 amps of current, each, so if you are just using your bike's battery, yeah, the voltage will drop a bit when you connect that large a load. That is more than turning on your headlight.

Try your same tests, but run jumper cables to your car battery with the car NOT running. See if the voltage does not drop quite as much.

I think your alternating coils might be due to the ignitor. Normally it's not doing its thing until the power is on and the crank is spinning, but there might be a randomness to what coil is live when power is first applied.

.

 

[Guest]

Thanks for the replies guys, however I feel I've left out some critical information that would help somewhat...

The bike is basically frame and engine, that's it. I've got it hooked up to a car battery as I haven't got myself a new battery yet.

The engine is not cranking (no oil yet).

The voltage goes from about 12.6 down to about 10.6 just plugging the coil in.

To test for spark, I'm waving a screwdriver in front of the signal generator coil.

With all electronic items plugged in except for coils, R/R, stator, and indicators, I get over 12 volts everwhere on the harness.

It's only when I plug a coil in that it drops.

Also, the end of the crankshaft is positioned so that the metal bits that would typically fire the signal generator are positioned away from the coils.

Hopefully that helps somewhat... sorry if it's confusing... it's messing with my head.

 

[posplayr]

Thanks for the replies guys, however I feel I've left out some critical information that would help somewhat...

The bike is basically frame and engine, that's it. I've got it hooked up to a car battery as I haven't got myself a new battery yet.

The engine is not cranking (no oil yet).

The voltage goes from about 12.6 down to about 10.6 just plugging the coil in.

To test for spark, I'm waving a screwdriver in front of the signal generator coil.

With all electronic items plugged in except for coils, R/R, stator, and indicators, I get over 12 volts everwhere on the harness.

It's only when I plug a coil in that it drops.

Also, the end of the crankshaft is positioned so that the metal bits that would typically fire the signal generator are positioned away from the coils.

Hopefully that helps somewhat... sorry if it's confusing... it's messing with my head.

Where is that Sparks and Magic Voodo Doll????

 

[Guest]

Where is that Sparks and Magic Voodo Doll????

That's what I'd like to know! I really think I need to get back in there and see what happens with the igniter disconnected... that might hopefully narrow it down.

It's just really odd how the crankshaft hasn't moved, yet the voltage drop moved from one coil to the other... weirdness...

 

[Steve]

It's just really odd how the crankshaft hasn't moved, yet the voltage drop moved from one coil to the other... weirdness...

..., but there might be a randomness to what coil is live when power is first applied.

...............................

 

[Guest]

...............................

Errr... yeah... sorry Steve, I believe I was suffering some form of inability-to-read-itis today

I ended up working midnight to 1:30am and then 6am through to 2:30pm, so I wasn't thinking and reading as clearly as I should have been...

Anyway, I still haven't gotten to further testing yet, hopefully tomorrow night will get that done.

So, firstly, let me get this bit clear in my head... given this is a twin, and the trigger on the end of the crankshaft has two posts on it that should affect both signal generator coils at the same time, shouldn't that mean both plugs fire simultaneously?

The crankshaft is in about the same orientation now as shown below, so when the ignition and kill switch are on, neither coil should be driven to ground to fire a spark:



What that makes me think is something is awry in the igniter (sounds like you think the same by your comment) that is causing one coil to be driven to ground when power is applied, rather than only when the signal generator triggers it.

Does that make some sense?

To test my coils, is it safe to use a jumper lead and just sort of flick the appropriate wire for the coils to ground? By that, I mean a very very quick grounding of the other side of the primary on the coil, not leaving it grounded for any length of time. That should fire a spark if it's safe to do right?

Is any of this making sense? Still a little on the tired side so hopefully I'm not rambling or going off on a tangent too much...

 

[Guest]

The ignitor alternately shorts the 1-4 coil and then the 2-3 coil to ground using a solid state device. Which ever one is shorting will pull the voltage down.

The power to both 1-4 and 2-3 comes from exatly the same place ; there is a crimp in the harness right under the gas tank.

The drop comes from that crimp or somewhere further upstream at the kill switch->fuse box->ignition switch->R/R "T"-> Battery

If you look at my link for "yet another coil relay mod" I have mapped it out

I finally found your "yet another coil relay mod" and will look through that also.

Once again, thanks guys, and apologies for not giving 100% of the info up front... brain farts today I'm afraid.

 

[posplayr]

I finally found your "yet another coil relay mod" and will look through that also.

Once again, thanks guys, and apologies for not giving 100% of the info up front... brain farts today I'm afraid.

Sorry, I keep forgetting about 2 cylinder motors. I mapped this out a while back for how the firing goes for 4 and 2 cylinders.

http://www.thegsresources.com/_forum/showthread.php?t=168652&highlight=firing+order

 

[Guest]

Sorry, I keep forgetting about 2 cylinder motors. I mapped this out a while back for how the firing goes for 4 and 2 cylinders.

http://www.thegsresources.com/_forum/showthread.php?t=168652&highlight=firing+order

Cool thanks for that, so both coils fire alternately on a twin.

I wonder how that works with the governor then? It has two posts on it, does one have some other material embedded in it to only fire one coil at a time and the other one is just for balance?

I'm probably over thinking this now but I'm curious...

 

[Guest]

I also just revised the schematic again now that I've had some sleep, and it definitely looks like it's safe to flick the coil to ground to test fire for spark.

There's a capacitor on the output side of the output transistor, but at 0.15uF 400V, that would just be a suppressor to protect the transistor from spikes I would imagine.