1980 GS550ES signal generator

[jasper]

So I'm chasing this weak spark issue and I think I've traced the problem to a faulty ignitor. I'm only sometimes getting power to one of my coils and this problem goes back all the way to the ignitor and given the operating symptoms it sort of makes sense...although it doesn't explain why I'm getting weak sparks from both coils.

In my testing though I also checked the impedances of the signal generator (that's the inductive pickups underneath the right side cover at the crank). I measure 68 ohms across each of the (green/white-blackwhite) and (brown-black/white) wires.

The service manual I downloaded from BassCliff says that I should be seeing between 250 and 500 ohms across these wires, but the manual is for an 1984 GS550.

Of course I accept that there could be multiple problems with the bike, but before I go and replace the wrong part, or both parts needlessly, I thought I'd post here and see if anybody can tell me if the parts changed between 1980 and 1984.

I also wonder if faulty signal generators would result in weak sparks.

Thanks - any help or advice is appreciated.

[tom203]

So I'm chasing this weak spark issue and I think I've traced the problem to a faulty ignitor. I'm only sometimes getting power to one of my coils and this problem goes back all the way to the ignitor and given the operating symptoms it sort of makes sense...although it doesn't explain why I'm getting weak sparks from both coils.

In my testing though I also checked the impedances of the signal generator (that's the inductive pickups underneath the right side cover at the crank). I measure 68 ohms across each of the (green/white-blackwhite) and (brown-black/white) wires.

The service manual I downloaded from BassCliff says that I should be seeing between 250 and 500 ohms across these wires, but the manual is for an 1984 GS550.

Of course I accept that there could be multiple problems with the bike, but before I go and replace the wrong part, or both parts needlessly, I thought I'd post here and see if anybody can tell me if the parts changed between 1980 and 1984.

I also wonder if faulty signal generators would result in weak sparks.

Thanks - any help or advice is appreciated.

As far as resistances go, you need info from 80 model- my 81 650 (slightly different system) gives a reading of about 300 ohms between blue and green wires once UNPLUGGED from ignitor.
Try Mr Matchless' simple test; remove spark plugs #3 and #4, reattach plug wires and hold plugs against engine. Turn on ignition (and kill switch); flick a small screwdriver tip pass the signal coil for #1 and #4- plug 4 should fire, ditto for other coil.
Do you have good voltage to coils and ignitor ? 11 volts at least? You need clean connections and a decent battery/charging system to ensure this.

[jasper]

Thanks Tom - I suppose a part number cross would tell me what I need to know.

With regards other testing done...

1) Power to coils. I'm losing a0.5 volts through the ignition and kill switches. My battery is 12.4 and the coils are getting 11.9. I'm going to do the relay mod, but I'm certain that isn't my root problem.

2) I have removed plug four and grounded the neg electrode while running the starter. I did this with both the #4 and #3 wire. In all cases the spark is just a wimpy little orange thing. I also used a proper ignition tester. Using this device I could not get the spark to jump 6mm which is what I have been told is the requirement. I could barely jump a 1mm gap in fact. Wires check out fine for impedence, wire ends are new and check out fine also.

3) Along with the weak spark issue, I am now not geting power to one of my coils. I traced this all the way back to the ignitor...The manual I have shows a different plug end than teh one on my bike, so I can't test the ignitor using my multi meter - at least not with the manual I have. That's what got me thinking about whether the 1980 parts are different than teh later years.

Unfortunately my problem appears to be due to multiple issues.

[mike_of_bbg]

An 80 GS550ES? Did you mean GS550ET? See the model history:

http://www.thegsresources.com/gs_modelchart.htm

If yours is truly an 80, as in an 8 valve, you want the 80-82 manual (this link from BikeCliff's site):

http://www.mtsac.edu/~cliff/storage/gs/GS550_77-82_all.pdf

[spyug]

Before driving yourself crazy, change out the plug caps. I had this issue on my project 550 and I was at first convinced it was a defective coil. New plug caps and nice fat spark again.

Good luck.
Spyug

[jasper]

Mike - The panels on the sid eof the bike say GS50ES. It' spossible that these were changed but not likely. I saw a reference elsewhere (can't remember where) that in 1980 there was both a GS550E and a GS550ES. It's moot anyway, the engines and igniton systems will not be materially different.

It is an 8 valve that much is for sure. Thank you very much for teh link to the manual. I must have mised itthe first go-aroyund.

Spybug...............please read my post. The end caps are new and the resistance measures out correctly at 5k ohms.

Thanks guys.

[tom203]

1) Power to coils. I'm losing a0.5 volts through the ignition and kill switches. My battery is 12.4 and the coils are getting 11.9. I'm going to do the relay mod, but I'm certain that isn't my root problem.

2) I have removed plug four and grounded the neg electrode while running the starter. I did this with both the #4 and #3 wire. In all cases the spark is just a wimpy little orange thing. I also used a proper ignition tester. Using this device I could not get the spark to jump 6mm which is what I have been told is the requirement. I could barely jump a 1mm gap in fact. Wires check out fine for impedence, wire ends are new and check out fine also.

3) Along with the weak spark issue, I am now not geting power to one of my coils. I traced this all the way back to the ignitor...The manual I have shows a different plug end than teh one on my bike, so I can't test the ignitor using my multi meter - at least not with the manual I have. That's what got me thinking about whether the 1980 parts are different than teh later years.

Unfortunately my problem appears to be due to multiple issues.

Try new plug caps like spyug said.
Issue #1; 12.4 v is low for battery, what happens when you crank it- maybe voltage at coils drops to 9.
Issue #2; 6mm is a long jump, but a" nice fat spark " is needed.

Do Mr. Matchless test- it tests whether the ignitor is responding to signal coil assuming wires have good connection. remember that coils get positive power from ignition and kill switch at all times- they only get negative power when ignitor is in the mood.

[jasper]

Fat lot of good that manual does me. It describes an old fashioned points and condenser type ignition system. Mine has the electronic ignition.



The more I read on-line here the more I realize that 1980 was a b@stard transitional year for the GS bikes....and the 550 is the red headed one.

[jasper]

Try new plug caps like spyug said.
Issue #1; 12.4 v is low for battery, what happens when you crank it- maybe voltage at coils drops to 9.
Issue #2; 6mm is a long jump, but a" nice fat spark " is needed.

Do Mr. Matchless test- it tests whether the ignitor is responding to signal coil assuming wires have good connection. remember that coils get positive power from ignition and kill switch at all times- they only get negative power when ignitor is in the mood.

I'm not buying new caps

I checked the voltage at the battery during cranking and it did indeed drop, but to 11.x volts not 9.x volts.

6mm was advised by a local bike shop with a good reputation. I note the manual says to benchtest at an 8mm gap.

The idea with the Matchless test is that it check for spark without the drain associated with the starter correct? I will try this, but the data and observations I have so far do not indicate that a lack of juice to the coils is my root problem. I agree it's not helping.

I willuse this technique for future testing though. At the moment the bike is in pieces so I can't try it today.

Given that Tom sees 300 ohms across his signal coils, and given that there doesn't seem to be any other reference, I am inclined to believe that the 68 ohms I am seeing indicates a problem.

A buddy says he has a spare for me, but I haven't verified it's the same part yet. I hope to get to this today.

Of course I still have that nasty issue that's cropped up with the ignitor only putting out juice to one of my coils. The igntor is out now and I'm hitting a bike shop on the way home to see if they have a spare in stock.

[mike_of_bbg]

Just making sure we're talking about an 8V 550 vs. a 16V 550 - the ESes that I've seen are 83-85 IIRC and your talk of downloading a 1984 manual gave me pause. Their ignition systems are quite different.

Have you checked the primary impedance of the coils? What is your secondary impedance, other than "fine"? With NGK 5k caps it should actually be about 10k lower than what's stated in the manual. Seems typical is about 14k ohms for the coil itself including wires but not caps - wires are negligible - plus the caps. The stock caps seem to run about 10k ohms.

Being an 80 model with 8V motor, you should have mechanical advance. I think 68 ohms for the sig gen is right in line but I'd have to check the manual to be sure. You can replace both the sig gen and the ignitor with a Dyna DS3-2 for about $120. Assuming your coils and wiring are good you should be set, but check your charging system as soon as you get the bike running. Ignitor failures may be prompted by a hot charging system.

As mentioned, you should be getting constant +12V on the orange/white wire for each coil. The ignitor does not provide the +12V, though it is connected to the same circuit. It's the ground that is switched by the ignitor. If one of your coils is not getting its +12V, you need to check the wiring up to it.

[jasper]

Just making sure we're talking about an 8V 550 vs. a 16V 550 - the ESes that I've seen are 83-85 IIRC and your talk of downloading a 1984 manual gave me pause. Their ignition systems are quite different..

It's absolutely an 8V motor. The photographs in the 84 manual that I downloaded clearly show a different bike than mine, and the drawing of the ignitor connections are clearly different also.

Thank you for confirming this.

Have you checked the primary impedance of the coils? What is your secondary impedance, other than "fine"? With NGK 5k caps it should actually be about 10k lower than what's stated in the manual. Seems typical is about 14k ohms for the coil itself including wires but not caps - wires are negligible - plus the caps. The stock caps seem to run about 10k ohms.

The caps I have are 5k ohm caps which I understand are the commonly available part now. The impedance at the primary coils were 4 ohms each. At the secondary I measured 28k ohms *without* the caps. I verified the caps at 5k ohms so that would make the total impedance 33k ohms although I don't think I actually measured it.

Being an 80 model with 8V motor, you should have mechanical advance. I think 68 ohms for the sig gen is right in line but I'd have to check the manual to be sure.

What manual would you be checking Mike? I sure would like a copy of it. So far I have an 84 manual which is close but doesn't match and a 77-82 manual which doesn't match at all (points and condensors). At any rate - I would dearly appreciate it if you could check this for me, it will make or break my efforts so far frankly.

You can replace both the sig gen and the ignitor with a Dyna DS3-2 for about $120.

That would be nice...but since I'm in vancouver Canada I might not be able to find these parts easily or for the good guy price. Do you have a link to an on-line seller for me perhaps?

Assuming your coils and wiring are good you should be set, but check your charging system as soon as you get the bike running. Ignitor failures may be prompted by a hot charging system.

Totally agree. If I can get the bike running long enough I will check this.

As mentioned, you should be getting constant +12V on the orange/white wire for each coil. The ignitor does not provide the +12V, though it is connected to the same circuit. It's the ground that is switched by the ignitor. If one of your coils is not getting its +12V, you need to check the wiring up to it.

Right....this has been a bugaboo from the start. I measured a healthy 12+ volts at the primaries at first, and then all of the suden one side goes dead....although I still see the same faint weak spark on both 1,4 and 2,3.

Get this:

The O/W wire splits right...so I would naturally suspect the splice BUT:

I have four wiresgoing into two coils

O/W(1,4)
W

O/W(2,3)
B/Y

voltage across O/W(1,4) - W is 12V

voltage across O/W(2,3) - B/Y is 0V

voltage across O/W(1,4) - B/Y is 0V

voltage across O/W(2,3) - W is 12V

Clearly the O/W wires are good and it is the B/Y wire that's dead.

I traced these wires all the way back to the ignitor (at which point the O/W wire is a single not double) and it's the same pattern....

iO/W-W is 12V

O/W-B/Y is 0V

Do you agree that the ignitor is now suspect?

Arrgh.

[mike_of_bbg]

The caps I have are 5k ohm caps which I understand are the commonly available part now. The impedance at the primary coils were 4 ohms each. At the secondary I measured 28k ohms *without* the caps. I verified the caps at 5k ohms so that would make the total impedance 33k ohms although I don't think I actually measured it.

That does seem high to me on the secondary. Remember you have two caps so 28k coil only plus two, 5k caps = 38k. I'd expect 12-15k for the coil only, or 22-25k with the NGK caps. Are the coils stock? Anybody else with me on that? Not that it would necessarily not work at that.

What manual would you be checking Mike? I sure would like a copy of it. So far I have an 84 manual which is close but doesn't match and a 77-82 manual which doesn't match at all (points and condensors).

I'm checking the Clymer GS550 77-86 manual, their #M373. It's a paper manual (how quaint). They say 60-80 ohms for the sig gen on 80-82 EI models, so you're right down the middle. The 83+ models had higher impedances (250-500). Some models got moved up to newer ignitions before others (which is why Dyna's description only says -81 for the DS3-2 though it clearly works on 82 mechanical advance models).

About the first half of that PDF manual covers the "original" GS550, which yes was points ignition. There are separate sections for differences in later models further down into the manual.

That would be nice...but since I'm in vancouver Canada I might not be able to find these parts easily or for the good guy price. Do you have a link to an on-line seller for me perhaps?

The lowest price I've seen is from a seller called ATVGALAXY on eBay; that was the $120 shipped I was thinking, not knowing you were from the worlds' second-largest country by area. They do say they ship "worldwide". Z1 Enterprises is a great vendor, and I also believe they'll ship internationally though their price is a little bit higher.

BTW, we'd know where you were if you added that in your user CP (hint, hint - you can also add your bike to your sig).

So whereabouts in the great north are you? I'm first gen US born, but have relatives stretching from Toronto to Kamloops.

Right....this has been a bugaboo from the start. I measured a healthy 12+ volts at the primaries at first, and then all of the suden one side goes dead....although I still see the same faint weak spark on both 1,4 and 2,3.

Get this:

The O/W wire splits right...so I would naturally suspect the splice BUT:

I have four wiresgoing into two coils

O/W(1,4)
W

O/W(2,3)
B/Y

voltage across O/W(1,4) - W is 12V

voltage across O/W(2,3) - B/Y is 0V

voltage across O/W(1,4) - B/Y is 0V

voltage across O/W(2,3) - W is 12V

Clearly the O/W wires are good and it is the B/Y wire that's dead.

I traced these wires all the way back to the ignitor (at which point the O/W wire is a single not double) and it's the same pattern....

iO/W-W is 12V

O/W-B/Y is 0V

Do you agree that the ignitor is now suspect?

Arrgh.

The ignitor certainly might be suspect - but not necessarily from your results. Remember that the ignitor controls the GROUND! Both coils might not be grounded. In fact, I've sometimes theorized that perhaps the ignitor acts like a digital SPDT switch, switching the ground between the coils as instructed by the sig gen. Thus only one coil at a time would ever be grounded. Alas I've already gone Dyna and can't test that theory out now. It would make sense for a symmetric failure between both coils.

What I'm saying is that you should check your coil O/W leads against the bike ground, not the coil ground. You can try "bumping" the starter to see if you can get the rotor magnet on the other side and see if the other coil is grounded (might need to do that a couple of times) - that would be the first step to confirming the operation I've theorized

[jasper]

Thanks for you help Mike - I really appreciate it.

I created a signature and added my location. I'm in North Vancouver BC...wet but peaceful.

1) I lied about the secondary coil impedances. Not intentionally, I was working from memory and frankly it sucks. Your post jigged it though. I measured 14k ohms without the caps...which are NGK - so that checks out. Sorry about the misdirection.

2) Sounds like my signal coils are fine. I am happy with that because I thought it was odd that *both* the pickups were equally bad...and I'm getting a spark so I know they're working right?

3) I'll look around locally before I order on-line just because of the delay and hassle involved with cross border shipping. In fact we've determined that I don't need a set of signal coils right? That leaves the ignitor but....

4) Oh I see - Does the Dyna replaces both pieces with a single part?

5) So if my signal coils are ok, and my coils are ok, and my wires are ok, and my caps are ok. That should leave my ignitor. I also remember now that the "knob" on the crank end (I guess it's a magnet) was in line with one of the signal when I was doing my tests last night and I wondered this morning if that was grounding one of the coils resulting in zero voltage.

I can rotate the crank using a 19mm wrench so I'll first rotate the crank so that both signal coils are open, and then check the voltage from O/W to GND for both coils. Then I'll try your experiment to test your theory which makes sense to me.

With regards the ignitor, I do understand the role of this device is to ground the primary circuit which induces voltage in the secondary circuit.

The problem is....if I rule the ignitor out then WTF is going on with my spark!?!



Back to voltage during cranking I guess, and the relay mod should help this.


As a by the by...when I took the bike apart last night I noticed that the voltage regulator connections were pretty badly corroded, the one red wire in particular. Whaddya think?

[tom203]

[QUOTE=mike_of_bbg;




The ignitor certainly might be suspect - but not necessarily from your results. Remember that the ignitor controls the GROUND! Both coils might not be grounded. In fact, I've sometimes theorized that perhaps the ignitor acts like a digital SPDT switch, switching the ground between the coils as instructed by the sig gen. Thus only one coil at a time would ever be grounded. Alas I've already gone Dyna and can't test that theory out now. It would make sense for a symmetric failure between both coils.

What I'm saying is that you should check your coil O/W leads against the bike ground, not the coil ground. You can try "bumping" the starter to see if you can get the rotor magnet on the other side and see if the other coil is grounded (might need to do that a couple of times) - that would be the first step to confirming the operation I've theorized [/QUOTE]


I suspect he has signal coils not points. Yes, I think that the ignitor is just a electronic switch and at times one coil could show 12 volts across its primary wires while other coil shows nothing. As you said rotate crank to another position. In any event, the idea (mr. Matchless test ) is to test whether the ignitor responds to signal coils. You need decent voltage both to coils and ignitor box, but maybe his ignitor box is only responding to one signal coil. I keep wondering why suzuki had different ignitor boxes- the ignitor doesn't care whether its sparking a 450 cc or 1100 cc motor- maybe they were just experimenting with different suppliers.

[jasper]

Hi Tom;

I have signal coils not points. That has been established. It doesn't change any of Mikes good advice.

Given our discussion and my observations I now believe the lack of 12V to one of my coils is because of how the trigger magnet was oriented in relation to my signal coils.

In fact I always saw the same weak spark at all cylinders which would not be possible if one of my coils was not getting any power. This was bugging me, but now that we've astablished it's possible for one coil to see 12V while the other does not, it no longer does.

Problem is though.....my problem with the weak spark persists!!!