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Coil Issues..

  • Thread starter Thread starter Anonymous
  • Start date Start date
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Anonymous

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Hi All

My 1980 GS750E was running great until I thought I would try to get more voltage at the coils. Battery showed 12.45 V, at the coils respectively I showed 9.45 and 9.34, so, I thought I would check connections, oh yea, I took the liberty of cutting off the connector near the coils and soldered them, same readings. Took the bike out for a spin and did not notice any improvement in performance. The main reason for looking at this part of the system was super rich looking plugs, black and sooty, I did rebuild the carbs in accordance to the carb rebuild series on this site, made sure they were clean. My spark on cylinders 1 and 4 is orange, very weak.

Getting back to the point at hand. I just checked the readings again and this is what blows me away without any other adjustments, the coil on the left if your are sitting on the bike reads 9.98 (low I know...) before the coil itself, the inboard voltage, the coil on the right reads.....are you ready for this....... .115..yep... .115 not even a volt, and just last week it read fairly close to what the other read any suggestions on where to start?, I was checking connections to the coils and undoing the electrical tape and pulled the solder joint apart on the coil in question (right side if seated on bike), put it back together and thats when the readings went wacky.

Per Earl I started with the voltage at the battery and went to the fuse box, all checks out within a half a volt, then to the ignitor, it checks out, I am at a loss.

Ohms at both coils are 4.5, reasonable and within range. HELP.. would getting Accel coils and a Dyna S system fix this, or is it deeper. :cry:

Thanks is advance

Scott
 
First thing I would check would be the ign switch to see if there is a voltage loss thru the switch. That could be the reason the coil voltage is low. I would also go back and check your coil connections
 
SqDancerLynn1 said:
First thing I would check would be the ign switch to see if there is a voltage loss thru the switch. That could be the reason the coil voltage is low. I would also go back and check your coil connections
Click to expand...
Possibly check the kill switch also while you are looking fo a connection with high resistasnce.
I is odd however that your voltage readings are diferent on each coil. that would cause me to suspect something within the ignitor or the individual pointsin the case of point ignition..
 
Yea Scotty, I am a little suspicious of the kill switch now myself, it seems as if the voltage at the respective coils were fairly similiar until I cycled the switch a couple of times, I am going to go cycle the switch a few times a see if there is a difference. I will let you all know the outcome.

Lynn, I will check the ignition also, like I said in the original post, I soldered then resolderd the connections to the coils, that is when my problems actually started occuring, but I did cycle the kill switch a few times over the past couple of days while trying to figure it out. I think if the problem lies within the kill switch I will just turn the bike off with the key from now on :) Ignition switch here I come.

Thanks again.

Scott
 
One more note...while following the orange/white wire in question from the coil in question, I followed it until I saw that it made the turn in the harness and went towards the loom behind the headlight, would this mean that my problem is up at that end?, the other coil that also has a orange/white wire for the hot does not go up that way in the harness, it heads for the battery area. Does this make any sense?

Scott
 
The orange and white wire feeds positive current to both coils. Only one wire runs up to the ignition switch then branches off to both coils. The two individual grounds serve as switches for the coils.
 
coils voltage

coils voltage

When checking voltage at the coils make sure your multimeter negative probe is connected to ground (metal on bike or -'ve post of battery). If you check the coils with probes at the coil connector's negative terminal, on one coil you will see no voltage, and the proper voltage at the other.

BTW, I had the same problem with low voltage at my coils (9.5 volts), until I wired up a relay to bypass the ignition switch (as described many times in these forums). Then I got over 11 volts to my coils. I still need to go over all the connections in the harness though for further improvement.
 
scottjm said:
Yea Scotty, I am a little suspicious of the kill switch now myself, it seems as if the voltage at the respective coils were fairly similiar until I cycled the switch a couple of times, I am going to go cycle the switch a few times a see if there is a difference. I will let you all know the outcome.

Lynn, I will check the ignition also, like I said in the original post, I soldered then resolderd the connections to the coils, that is when my problems actually started occuring, but I did cycle the kill switch a few times over the past couple of days while trying to figure it out. I think if the problem lies within the kill switch I will just turn the bike off with the key from now on :) Ignition switch here I come.

Thanks again.

Scott
Click to expand...

Scott, We are all just guessing but since there is only one wire going to and from the kill switch, I really dont see how a high resistance in a switch of any kind could produce 2 diferent voltages. I would first work my way back from each coil. first check the primary side of each coil for and leakage to ground as a start.
 
First the good news, I took Canrocs advice and did positive to the coil hot wire and grounded it on the frame, this gave readings of more then 11 volts for both coils...very happy...thank you very much, it confused me because when I went hot wire to + and - to the other wire (black/green) on the same coil it gave me 9.8 Volts on and 0 on the other coil, as soon as I grounded the connection to a good ground on the frame the voltage shot up passed 11. I think I am thinking to hard on this...

Now for the confusing part to me...I rolled her out and started her up, number 3 exhaust got hot, number 4 got warm, and 1 and 2 stayed cold???? No spark to either,Huh?..I realize that 1 and 4 are on one coil, and 2 and 3 are on the other, how can this be then if a cylinder from both coils is firing???

I get confused easily, could it be a simple matter of changing spark plug wires?, they are the original (1980) wires. The plugs are new also with 500 miles on them, when checking the plugs on 1 and 2 they are wet with gas, on 3 and 4 they are carbon, black sooty.

Once again, thanks in advance

Scott
 
Voltage Drop

Voltage Drop

When you crank over your bike like you do a car the the battery voltage drops due to the high amperes drain by the starter say to 9 volts. This 9 volts also goes to the coils to start and run the ignition. So maybe the coils is designed to operate at 9 volts instead of 12 volts. Bypassing the resistance my cause a short coil life.

Just my 2 cents
Jake
 
coils and wires

coils and wires

scottjm said:
First the good news, I took Canrocs advice and did positive to the coil hot wire and grounded it on the frame, this gave readings of more then 11 volts for both coils...very happy...thank you very much, it confused me because when I went hot wire to + and - to the other wire (black/green) on the same coil it gave me 9.8 Volts on and 0 on the other coil, as soon as I grounded the connection to a good ground on the frame the voltage shot up passed 11. I think I am thinking to hard on this...

Now for the confusing part to me...I rolled her out and started her up, number 3 exhaust got hot, number 4 got warm, and 1 and 2 stayed cold???? No spark to either,Huh?..I realize that 1 and 4 are on one coil, and 2 and 3 are on the other, how can this be then if a cylinder from both coils is firing???

I get confused easily, could it be a simple matter of changing spark plug wires?, they are the original (1980) wires. The plugs are new also with 500 miles on them, when checking the plugs on 1 and 2 they are wet with gas, on 3 and 4 they are carbon, black sooty.

Once again, thanks in advance

Scott
Click to expand...

I had similar problems until I changes my spark plug caps. It is worth a try.. these don't cost much. You just twist off the old caps at the end of the wires, cut a small piece of wire off to get a clean wire end, and twist on the new plugs. Hopefully that will solve your problem, otherwise you might be looking at replacing wires on the coils (apparently that can be done) or replacing the coils.
 
I got to thinking about my problems while I was guiding on the river yesterday and had a thought, tell me what you think and if it makes a difference.

As I metioned before I cut the connectors off that go to the coils and soldered them, they had two orange and white wires and one white and one black and white. What would happen if I connected the wrong wire to the respective orange/white wires, what I am saying is that I may have inadvertently connected the wrong ground wire to each coil. Are they a common ground or do they have to be connected to the correct coil? Should I undo the wires and switch the white and black/white wires?

Also, cylinders 1 and 2 are cold and 3 and 4 are hot after a couple of minutes of running, this implies that both coils are working but not on cylinders 1 and 2...??

Scott
 
Stop the presses, I have found my problem and believe it or not I have my local Suzuki dealer dude to thank!!! The problem was not the coil at all since cylinders 3 and 4 were firing, the problem was FOULED PLUGS, I would have never thought of that, as soon as I changed all four of them I checked to see if all were firing and sure enough they were. I took her for a twenty mile trip and she pulled through all of the gears like she never had, I think that was in part to cleaning all the connections to the coils and gaining 2 + volts in the process. Anyway, another chapter in my saga. I still think I am going to get the Dyna S and some Accel coils after I rob a bank!!
I am going to check plug color when she cools down to see if I still ahve alean condition.

Thanks to all who responded, I will be using your services again in the near future.

Scott
 
I don't think I would be too quick to blame the coils. Fouling can result from mechanica, tuning etc problems. I run standard coils on a hotted up engine no problems. I fact I have not checked my plugs for..hmm..a while :))
 
Scotty, I have no idea why they fouled, but as soon as I changed all of them out it ran fine. To be honest with you I am pretty new to this plug fouling phenomenon, I was just about to surf the web to find out what exactly causes fouled plugs. I still think that I am having tuning problems and need to address them, I was hoping that getting more volts to the coils would give a more complete combustion and help lean out my plugs, but after yesterdays ride they are still black and sooty. I have the air screw turned out two and a half turns and will maybe try another half turn.

Scott
 
Please look at the plugs after each time you ride the bike ((starting right away))
and you may find that you are running rich. Let us know the color of each one the plugs ASAP and often. We all truly enjoy the learning experience.
 
You got it Scotty, here are the results of the plugs, I just checked em after another twenty miler, asd I turned the airscrews out a half turn on each carburetor, they all are at 3 turns out from bottom.

1 - Black sooty and a little wet, not dry and fluffy. This cyinder smells like gas more then the others upon removal of the plug
2 - Black, sooty, powdery but the insulator is now showing signs of going to a tan color (progress??)
3 - Black, sooty, same as number 2
4 - Black, not quite as sooty as other three, in fact the insulator is definetely showing signs of brown to tan in coloration.

Would a higher octane gas help? I am currently running 85
I am confident that the cylinders are carboned up, what is the best additive to remove this, I saw on an earlier post form a month ago but cannot find it now.. :(

Let me now your thoughts on this. I am ruling out incomplete combustion from inadequate voltage to the coils, I am now at 11.4V at both coils.

Float height possibly?, I have not monkeyed with those, I did a full dip and replaced all o-rings in carbs. Synched them also. I did have the floats off but ws very careful when replacinf them and did not bend or disrupt the tang on the floats.

Scott
 
I always just fool with my needles but my carbs were originally set by an expert and all i do is tweak them from time to time.. you better get the advice of others on this one.
The one thing that comes to mind first is when were the carbs worked on last and what was done to them? Also has anything at all been done to the engine recently??? Do you drive too slowly((lug the engine))
 
Scotty

Nothing major done to the engine, in fact nothing done to it at all.., and I was the one who followed the carb cleaning series verbatim from this website (it was great), even used compressed air. As far as lugging the engine, I can, with confidence, say no, it is not as if I red line it either but I take it into the high rpms from time to time and usually shift at higher RPMs. The country around here, Jackson Hole Wyoming, is hilly and the passes are fun to drive in low gears and pushing it. 8) ,,,.. I will continue to work on this and keep you posted about plug colors, hopefully tomorrow will bring another nice day to ride, they are numbered around here...

The plug fouling thing blows me away, it came on suddenly like a heart attack. She is acting alright now albeit rich. Running out of ideas so if anyone is inclined please buzz in.


And Scotty, you had inquired about when and why they fouled, all I can say is that it started acting up after I cut the connector off and soldered the wires together at the coil, just before the coil actually, maybe this has something to do with it.

Thanks again for everyones input in advance

Earl.....are you there,,,come in Earl...... :roll: :?: :roll:

Still Hopefull..... aka Scott
 
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