No voltage to coil

[phanham]

Ok, I need some help! I've got an 82 GS550LZ that was running like a champ a couple of weeks ago; however, it started to die suddenly when warming up. And now I can't get a spark at all. Coils have satisfactory resistance, but low voltage (9v) going to secondary, and can't get any reading for the primary. I've checked all connections, and did the "single point" ground at the R/R. I have not tried the coil relay mod. Any ideas? Also, how does this bike have mechanical timing and will a Dyna DS3-2 help? Thanks in advance for any help!

Some background - I've cleaned carbs correctly (completely disassembled, dipped, new Orings, vacuum synced, etc), new intake seals, adjusted valves, replaced stator and R/R (still having charging issues), new plugs/wires/caps, and probably a dozen other things I can't remember at the moment.

 

[posplayr]

Welcome from Fort Smith, I'm an old Razorback.
The voltage at the o/w (orange white) should be close to battery with the other sides going up and gown as thf igniter saturates the coils then releases the current thereby releasing a spark. Check both coils as you rotate the engine. When high both sides of the coil will be the same. When charging the coil there should be over 10 volts across the coil.

you are probsbly dropping voltage and charging poorly.if you get it running do the quick test in my signature and report the results.

 

[duaneage]

Check the mounting bolts for the coil. That is where it grounds to the frame. The engine has a ground wire that completes the circuit. Try running a wire temporarily from the coil mount to the engine block.
You might need new high tension leads. I found solid wire core leads ( Accel ) and replaced mine. you can pull the leads out after removing the glue. I resealed mine with permatex 97 and it looked and worked original.
If you still have low secondary output then maybe you need new coils. Heat affects coils and they may be degraded. Post in Parts Wanted fora pair, we all have spares.

 

[posplayr]

Check the mounting bolts for the coil. That is where it grounds to the frame. The engine has a ground wire that completes the circuit. Try running a wire temporarily from the coil mount to the engine block.
You might need new high tension leads. I found solid wire core leads ( Accel ) and replaced mine. you can pull the leads out after removing the glue. I resealed mine with permatex 97 and it looked and worked original.
If you still have low secondary output then maybe you need new coils. Heat affects coils and they may be degraded. Post in Parts Wanted fora pair, we all have spares.

If you coils is grounded it will not fire. NO GROUND.

 

[duaneage]

Do you know how coils work?
Take a look at any bike schematic and you'll see the secondary is grounded.

 

[mike_of_bbg]

I would say that he understands very very well how the coils work. The igniter provides the working ground for the primary. The plugs are fired when the ground is pulled, as done by the igniter, as directed by the signal generator.

And that's what I get for typing too quickly. The igniter provides the working ground for the primary, not the secondary.

 

[posplayr]

Do you know how coils work?
Take a look at any bike schematic and you'll see the secondary is grounded.

With wasted spark both plugs fire simultaneously (but jump gap in opposite direction) with the path going through one coil secondary. So you have a series circuit consisting of:

• Coil secondary
• Two high tension leads for the wasted spark pair.
• Two spark plugs
• Head.

The coil secondary is only grounded is you consider the spark plug gap as a short.

 

[mike_of_bbg]

Ok, I need some help! I've got an 82 GS550LZ that was running like a champ a couple of weeks ago; however, it started to die suddenly when warming up. And now I can't get a spark at all. Coils have satisfactory resistance

Define satisfactory. Particularly the secondary. Thought I'd expect with new boots that it should be OK.

, but low voltage (9v) going to secondary

What is your battery voltage? Typically it's nice to see <1V drop from battery to coils. If your battery is only putting out 10V right now that may be true. Also that igniter gets about the same voltage and might have trouble working if it's too low. Make sure your battery is well charged (using a <2A charger).

And that's your primary, not secondary. Secondary is between plugs 1-4 and 2-3.

, and can't get any reading for the primary.

There shouldn't be any voltage at the secondary except a very high blip when the plugs fire - and you don't want to have a multitester hooked up when that happens!

I've checked all connections, and did the "single point" ground at the R/R. I have not tried the coil relay mod. Any ideas? Also, how does this bike have mechanical timing and will a Dyna DS3-2 help? Thanks in advance for any help!

Some background - I've cleaned carbs correctly (completely disassembled, dipped, new Orings, vacuum synced, etc), new intake seals, adjusted valves, replaced stator and R/R (still having charging issues), new plugs/wires/caps, and probably a dozen other things I can't remember at the moment.

What are your charging problems? Too much V? That can kill an igniter! I remember one member went through two $400 brand new Suzuki igniters on his twin due to charging issues. But of course it helps to have a running bike to troubleshoot charging issues, too. Coil relay mod will help reduce the voltage loss between battery and coils. DS3-2 is a great choice for your bike if you determine or decide your igniter or sig gen is dead. Pricey troubleshooting step if your igniter isn't dead.

 

[phanham]

I don't remember exact resistance in coils, but was well within tolerances. Battery voltage is solid 12v. I tested voltage going to coils with probes on connections to coils, and turned key /switch on. Not sure if that is 100% correct or not. As for charging problems, it was non-existent when running. Stator resistance and voltage good, R/R seemed to check good, but no battery charging detected. That's why I did the single point ground mod, granted it was after it decided to stop running at all.

 

[phanham]

Btw, no glued leads to coils on this model. Wires go into coils.

 

[mike_of_bbg]

OK, sounds like you might have aftermarket coils then.

3V drop from battery to coils is way too much. Either figure out and correct where you're dropping voltage or it's time for the coil relay mod.

What did you put in for a new R/R? New Stator is testing OK?

 

[phanham]

OK, sounds like you might have aftermarket coils then.

3V drop from battery to coils is way too much. Either figure out and correct where you're dropping voltage or it's time for the coil relay mod.

What did you put in for a new R/R? New Stator is testing OK?

Coils look pretty old /original, do you really think they are aftermarket? Stator and R/R are probably cheap Chinese parts (I didn't know about GSResources at the time).

I will try to find time soon to do the coil relay mod, but wondering if this bike has mechanical advance for the Dyna mod.

 

[phanham]

Primary coil

 

[phanham]

Secondary coil

 

[phanham]

Dyna DS3-2 candidate?

 

[mike_of_bbg]

I can't really see the mechanical advance mech past the sig gen plate. Looks familiar though. If your engine is an 82 GS550 though, yep, the DS3-2 is the Dyna you would want. Kind of stabbing in the dark, though. We know your coil voltages are low, so a coil relay mod would be in order first. Not sure that they're low enough where they would never fire at all, if that's what you're seeing.

Those coils definitely look stock. The wires are epoxied on the inside IIRC. I was thinking you had removable wires, which would be a sign of non-stock coils.

 

[phanham]

Alright, I did the coil mod and now secondary is seeing a much improved 11v; however, I'm still not getting spark, nor a voltage reading going to primary. Is this the notorious GS550 ignitor issue? Is next step the Dyna DS3-2?

Btw, in case I have terminology wrong, I'm calling the left side coil primary (orange & white), and right side secondary (orange & black)

 

[mike_of_bbg]

The secondary is the half of the coil that *both* spark plug wires come out of. So, you should never see voltage on the secondary. The only test for the secondary is to measure across the wires for 1-4 or 2-3. The primary coil has a (+) and a (-). The (+) is constant, and is probably where you're measuring the 11V; 11V is better than 9V for sure. The (-) comes from the igniter: that side is grounded when the igniter is building the field in the coil, and that ground is pulled (no connection) at the moment the igniter wants to fire that coil. I've never confirmed it, but I think the igniter just switches the ground between the coils.

So, if you're measuring the voltage at the black or white wires at the coils (instead of the orange-white), you would either see 0V to ground if the coil is energized, or darn near the orange-white voltage if it is not. And it is very likely that you will see one on each, and that it will change if you crank your motor over 1/2 turn (you might need to do that 2 or 3 times). Your coil's impedance is very low (<10 ohms), and your ohmmeter's should be very high (100k ohms or more), so almost all of the voltage drop that you see on the un-grounded coil by completing the circuit with your multi-tester should be across the ohmmeter itself.

As for whether the Dyna will fix the issue: there's not a whole lot left besides the sig gen and the igniter. And with your charging system being bad, it's frequently when those fail that a voltage spike occurs and fries those 30-year-old transistors for good. So I think it's likely.

The best test is to use a known good igniter. My old igniter would work until it got hot (usually ~30 minutes of riding). It made a great test igniter and I loaned it out a few times; but it didn't make it back to me the last time. IIRC one of the aftermarket manuals had some sort of test one could perform for the igniter. I'll see if I can find it.

 

[phanham]

Thanks Mike. I went ahead and ordered the Dyna. After perusing through older threads, it seems like it's just gotta be the ignitor has burned up.

Thanks everyone for the help. Feels like these bikes sometimes fight you every step sometimes! I'll update once Dyna is installed in case this thread helps others.

 

[mike_of_bbg]

Here's a tip on the Dyna. They include a spacer for electronic ignition bikes (which have a taller rotor), but it's a little too tall - at least when I was installing mine it was and it was common at the time. The spacer is intended to prevent the rotor from coming off of the mechanical advance. But when I tightened my crank bolt with the spacer the rotor was unable to advance. I ended up sanding a few tenths of a millimeter off the end of my rotor. Or you could find a thinner washer to use in place of the included spacer. Anyway, just make sure to check that the rotor is free to advance after installation.

And here, since I was taking pics for another thread I snapped a quick one of the Dyna installed on my 550LZ. Since our motors are the same it's likely that the timing orientation should be pretty close to where you want to start. Though I seem to recall reading somewhere that they had switched over to smaller modules?