1980 suzuki gs550L help

[awaselito]

hi guys, well, I'm ganna need some help please. my buddy is having problems
with his bike. a 1980 Suzuki gs550L. he had told me that his bike a while
back was running like as if it was running on two cylinders, it would do
this off and on. now he states that its like this all the time. he installed
a new coil and nothing. he did this because the two inner cylinders are not
working. i don't know if its the wiring since he bought a new coil. what i
did was start the bike up, took off the outer plug wires one at a time. and
the bike would want to shut down. then when i took off the inner plug wires
one at a time the bike was like if i did nothing. engine stayed running the
same. i touched the inner pipes and they were cold. well, i can keep my
finger on the pipes. but the outer ones were hot. now, what do you all think
of this and what do you all think i should try for him. i haven't checked
the wiring yet. can some one help?

[doctorgonzo]

Well, 2 and 3 are dead if they are cold and no change when the plug wires pulled. take the spark plug out of each of 2 and 3 (one at a time) attach the plug wire back to it and lay it against the cylinder head, do you see a strong spark when the bike is cranked? If you do then probably fuel related, if you don't then it's electric.

[hikermikem]

To rule out the coils, you can simply switch the #1 & #4 plug wires with #2 & #3. The left coil works 1 & 4, the right coil works 2 & 3. If the "non-firing cylinder" symptoms switch to cylinders 1 & 4, then you have either a bad coil, or the wires and/or caps are bad on that coil.

If all is fine, then its a fuel problem.

[TheCafeKid]

Woah woah woah. I DONT think you want to put the plug wires from two and three on one and four. You can do this to see if you have spark using the grounding method above, but puting them in the motor and trying to start it like this will cause it to backfire horribly and POSSIBLY do damage to the motor. Just so everyone is clear.

[awaselito]

well, i just did the spark plug removal meaning i took off the spark plug and laid it on the bare head and no spark. on 2-3 cylinders. remember that he replaced that coil with a new one thinking that it was the coil. but that did not fix it. now i seen that their are orange/w a white strip wires going in a harness to the headlight which from the coils both run to one wire to the head light. and then their is a white wire which runs the 1-4 plugs ( coil ) and a wire that is black/w a yellow line that runs the 2-3 ( coil ) plugs that run back under the battery box. i thought since the two orange wires are running together to the headlight and the 1-4 plugs are working then those wires should be ok but the ones to the back i don't know. i think the ones running to the back are hot but i don't know.

[Dave8338]

Can you say Multi-testor, anyone? :?

[awaselito]

yea, but i can also say, tell me what to test and how to test it. what settings to test it on the tester and so on. i'm really dumb.lol please help.

[cp___32]

Well seeing as I am currently trying to fix a similar problem only my bike hasn't had spark at any cylinder yet...
Get a meter and turn it to DV Volts...
Use the red probe and touch the + terminal on the battery, then touch the black probe to the negative terminal. This will tell you how much Voltage your battery has (should be around 12V)

Turn the key to the ON position...
Use the red probe and touch one of the orange and white wires running to the coil, and at the same time touch the black probe to something that it grounded (like an unpainted, metal surface on the frame or motor)

My bike read 10.5V at each terminal on the Coil, except one, the white wire read 0V...but as stated my bike doesn't run.

That's pretty much the standard way I test for Voltage. As for specific numbers that the meter should show at any given part of the bike, I'll have to defer to the experts here, but generally speaking, things that should have power, should show something very close to what you see on your battery.

[awaselito]

Well seeing as I am currently trying to fix a similar problem only my bike hasn't had spark at any cylinder yet...
Get a meter and turn it to DV Volts...
Use the red probe and touch the + terminal on the battery, then touch the black probe to the negative terminal. This will tell you how much Voltage your battery has (should be around 12V)

Turn the key to the ON position...
Use the red probe and touch one of the orange and white wires running to the coil, and at the same time touch the black probe to something that it grounded (like an unpainted, metal surface on the frame or motor)

My bike read 10.5V at each terminal on the Coil, except one, the white wire read 0V...but as stated my bike doesn't run.

That's pretty much the standard way I test for Voltage. As for specific numbers that the meter should show at any given part of the bike, I'll have to defer to the experts here, but generally speaking, things that should have power, should show something very close to what you see on your battery.

thank you, i'm ganna give that a shot.

[DimitriT]

Pull the plug from #2 and #3 and tell us the color. It's most
likely the carbs are dirty but it could also be tight valve clearance
or an electrical problem.

[awaselito]

Pull the plug from #2 and #3 and tell us the color. It's most
likely the carbs are dirty but it could also be tight valve clearance
or an electrical problem.

well, i just did the spark plug removal meaning i took off the spark plug and laid it on the bare head and no spark. on 2-3 cylinders. remember that he replaced that coil with a new one thinking that it was the coil. but that did not fix it. now i seen that their are orange/w a white strip wires going in a harness to the headlight which from the coils both run to one wire to the head light. and then their is a white wire which runs the 1-4 plugs ( coil ) and a wire that is black/w a yellow line that runs the 2-3 ( coil ) plugs that run back under the battery box. i thought since the two orange wires are running together to the headlight and the 1-4 plugs are working then those wires should be ok but the ones to the back i don't know. i think the ones running to the back are hot but i don't know.:sad:

[awaselito]

question, on the coils. is the a hot and a ground wire . on the new coil he bought i saw that one wire side had a + and the other wire side had a -. i talked to him today and asked him again what led to this and he told me that it started very slow. meaning he would ride the bike and as he was riding the bike it would miss for like a sec or two. and that just got worse as time went on. so its something that was going bad or that came loose or something.i'm not sure if i should check the black/w yellow strip wire from the none working coil that go's under the battery box to see if their is something going on down their. the white wire is going to the same place but that coil works.

[doctorgonzo]

question, on the coils. is the a hot and a ground wire . on the new coil he bought i saw that one wire side had a + and the other wire side had a -. i talked to him today and asked him again what led to this and he told me that it started very slow. meaning he would ride the bike and as he was riding the bike it would miss for like a sec or two. and that just got worse as time went on. so its something that was going bad or that came loose or something.i'm not sure if i should check the black/w yellow strip wire from the none working coil that go's under the battery box to see if their is something going on down their. the white wire is going to the same place but that coil works.

Search the forum for the "Coil relay Mod" it explains the wires very well. The orange and white are the juice coming to the coils, they come from the battery via the kill switch on the bike. The black with stripes wires are from the igniter.

[doctorgonzo]

Also, you say he replaced the coil.... was it a stock or aftermarket... if it aftermarket, what kind of wires did he use... did he replace the plug caps, did he use suppression wires?

[awaselito]

ok, checked the coils with the volt meter. the coil that fires, orange w /white stripe. reads 08.5 and the white wire on the same coil reads 00.1. then on the coil that don't fire or cylinder that don't fire, orange w/white stripe reads 08.5 and the black w/yellow stripe line reads 00.0 don't know what these numbers mean but their you go. would anyone happen to have a wiring diagram of the wiring for this bike?