More bike issues

[bobiii84]

So I had a problem with my electrical a while back and had a coil go bad and it shorted and blew out a fuse among other things. I replaced my fuse box with one in better shape, replaced the coils, replaced the plugs, and prepared my bike to run. I had winterized it since I was moving and didn't have the time to work on it so I had to fill the carbs back up with gas. When I tried to start it gas began dripping out of my airbox overflow. I assume one or many of my floats were stuck so I took the tank off, and took the backside of a screwdriver to where the floatbowls are. After this I tried to fire it up and it started, except, it had the same crappy sound it did when the issue first happened. It sounds and feels like it's running on two cylinders instead of all 4. I took a spark tester that plugs into the line and tested the spark. One coil is giving me good spark while the other seems quite weak. The coils are brand new and it's doing what it did before so right off the bat, I don't think it's the coil. What would affect the power going to the coils? I'm not home right now so can't go through my manual to see what the voltage would be, but any advice would be greatly appreciated. Thanks!

Also, this is for my 1980 GS550L.

[duaneage]

Have you tried new plug boots? They are about 4 dollars each.
Are the coils grounded well through the mounts? Measure the resistance between the coil mounting bolts and the engine, should be near zero ohms.
Reverse the coils from 1-4 to 2-3 and see if the problem moves or not. Might be the igniter or the pickups on the right side of the engine.

[SqDancerLynn1]

Check and make sure you have 12 volts on both coils..

[mike_of_bbg]

Do you have access to a multimeter where you are?

[bobiii84]

I'm not at home and the bike isn't with me. Sorry if it sounded like I was stuck somewhere I didn't want to be with the issues. I go back home tomorrow and wanted to have all my ducks in a row for when I have the time to work on it.

[mike_of_bbg]

Did you test your old coils before you replaced them? Was there a reason you chose to replace them? What did you replace them with? Are all of the pipes getting hot quickly when the bike is started?

The advice given so far is good. Check voltages at the coils. Check secondary resistances as well as boot resistances.

[bobiii84]

Alright so I finally got back and had time to run the tests you guys mentioned. When the issue first happened my left coil was melting with the key on so I opted to replace them both. I saved the right one with enough wire to be used in the future even As for the voltages, the batter wasn't fully charged yet but was reading 12.4 so I took reading anyway. Left coil showed 12.3v and the right showed 11.75v. I also checked coil to frame, or in this case coil to neg terminal. All the bolts read 0 resistance to the frame/neg terminal. I decided to take it a step further in case of a short and here's where I'm not really sure what I have. I'm going to try and make this simple so bear with me. The first column will show if I measured it against the neg/pos terminal, the next will show the wire color, and the last will show the resistance I got. According to my book, W and B/Y are the neg, while O and O/W are the pos.

LEFT COIL:
- W 0
- O/W 0 <-- I assume this means I have a short in that wire?
+ W -95K
+ O/W -95K

RIGHT COIL:
- W/O 0 <-- Why would the pos wire have 0 resistance to neg term?
- B/Y 64K <-- This doesn't make sense to me
+ W/O -95K
+ B/Y 1

Now when this first happened the short took out all the bulbs I had on at the time. Headlamp, left turn signals and left dash light all went. I would not be suprised if it took out another electrical part along the way. Does anyone have any ideas on this? Your advice is much appreciated, thanks!

[bobiii84]

Tested the signal generator today, every thing there seems to be where it should. Measured ~60 Ohms between each wire in it. I was going to test the igniter but two things stopped me. One, it has 6 wires that don't match the colors in the book so I don't quite know how to approach it. Two, I'm getting spark in both coils but one is weak. This tells me it's working because I'm getting spark at all right? Threw the charger back on and will check the spark again in the morning. Any advice?

[mike_of_bbg]

I think this was suggested earlier, but swap the coil connections and see if the weak spark moves to the other cylinders. If it doesn't, then it's probably the coil or coil wiring.

The coil fires because the ground is suddenly and completely disconnected from the primary and the magnetic field built up in the primary collapses - that induces the big voltage in the much larger secondary coil. If the disconnect is not sudden and clean (due to faulty/leaky components in the ignitor) that could cause weak spark.

Check your secondary resistances without the boots, and check the resistance of the boots as well. I think secondaries should be around 25k without the boots. The boots could be anywhere from 0 to 5k; if it's much higher they should be replaced. They're cheap and easy (they just screw on to the ends of the wires).

[bobiii84]

Went out today and plugged in the good, old coil that I took off a while back. The spark is still barely noticeable. I also noticed that the green coil I took off was not hot, but getting there quickly. The right coil that seems to be firing correctly wasn't even warm to the touch! I'm not sure what you mean when you say secondary resistance, sorry I know that when I crimped the wires they read about 9-10 Ohms resistance from metal boot to metal boot. These are the graphite core wires so the boot is not huge like the originals. They all seem to be fine though and the other side it sparking as it should. Is my voltage of 12.3v on the left coil too high? What would cause it to be borderline hot like that?

[mike_of_bbg]

OK, you're not running stock wires. I saw you replaced your coils but wasn't sure with what. The secondary is measured between plug connections wire-wire on the same coil. Usually if you're measuring the stock stuff you take the boots off to negate their effects, then test the boots separately. I hope you meant 10 kilohms or 10,000 ohms measuring the secondary, not 10 ohms. You'd have to check with the MFG to see if 10kohms is OK. That sounds low to me. Does the other coil measure the same?

You want the coil voltages to be as close to battery voltage as possible. Nothing wrong with what you're measuring there.

The ignitor's job is to give ground to the coil to build up the primary magnetic field (its time to do that is called dwell), then pull the ground to collapse the field right when the spark is needed. If you're just sitting there with the key on, yeah, current is flowing to make that field and the coil could get warm - even when everything is working just fine.

The ignitor is my primary suspect. The only way to really verify that would be to swap in a known working ignitor. The ignitor on my bike would start and run my bike just fine for about 1/2 hour, then overheat and cut out entirely. I could see if I can get it off without major surgery. Dyna S DS3-2 would really be the cure but that's $140 for a "hope this works" situation.

[bobiii84]

When you say plug connections wire to wire, are you referring to the coil itself or the plugs/wires? I wish this site had a draw option so you could just draw it up And yes, I meant 10k Ohms for the resistance. I can look online for an ignitor to see what I can find. When this happened before the old coil was melting and smelled of burnt electrical. My worry today was that it was getting hot and started to smell of that again. I'm not sure if I should be worried about it or not, but I tend to think it's not a good thing. Should the voltage to the coil stay the same even when starting/running it? I could try hooking the multimeter up to it while attempting to start and see if it changes?

[mike_of_bbg]

An ignition coil is basically a two-sided step-up transformer. The PRIMARY resistance is measured across the two wires going into your wiring harness (disconnected). The SECONDARY resistance is measured between the ends of the two plug wires coming out of that coil. The PRIMARY resistance should be about 3 ohms for EI coils. The SECONDARY resistance should be upwards of 10,000 ohms - stock coils would be around 20-30,000 ohms I think but 10k may be OK for your aftermarket coils. You'd have to check with the mfg on that.

With your coils only putting up 3 ohms of resistance on the primary winding, figure the power:

W = V^2/R = 12^2/3 = 48W.

That's the heat the coil has to dissipate when it's getting a constant source of 12V. About 80% of a 60W light bulb. When it's running that's lower as the voltage is intermittent. You're also probably moving a bit and running some air over it. Don't leave your bike ON and not running for long periods of time.

[mike_of_bbg]

My ignitor's not coming out. I just tried and the rear screw is pretty well seized on there. Short of airbox or swingarm removal I just don't see it happening.

See this post BTW from Jeff Saunders of Z1 Enterprises:

http://www.thegsresources.com/_forum/showpost.php?p=1361792&postcount=18

Never leave the igntion switched on. This can overheat components and fry coils (ask me how I know that one).

[bobiii84]

In that case, my primary resistance is 3-3.5 Ohms and the secondary is actually around 30-31k. I didn't really trim much of the wires before I crimped them though, probably why it's toward the higher end. I understand the heat it would put off, but why would it be only the left and not the right getting hot? Firing order? I tested this with the old stock one on the left but I will put the dyna back on later and test again. Hopefully I didn't fry a new coil out of ignorance I think I will try to get the igniter off sometime this week to test. Not sure how well that will go but I will also look for another to test it against. My fear is still how this all started. I don't want to spend and spend on parts only to have the bigger issue strike again. I love this bike but it's starting to cost me!