1 and 4 run, 2 and 3 have issues

[Big Red]

Hey Folks,

Having an issue here. still learning about all this stuff.

when i fire it up with the choke. right away the pipes off 1 and 4 start getting hot, but not 2 and 3. when i hit the throttle it will only get up to 4000rpm. checked plugs all getting spark. compression good. need to tune the carbs. it was running fine when i first put the carbs back on after a good cleaning. 2 months ago sitting mostly since then start up once an awhile but no time to really work on it.

I can't figure out if 2/3 are misfireing or not firing at all.

after i run it for a minute then pulle the plugs (new) all plugs are HOT. brand new plugs in 2/3 come out with new black stuff on it.

plug are wet if i try and start without the choke if it has been sitting acouple of days.

Any ideas i need it running better before putting the carbtune on it.

Thanks

[heater63]

I'm having a very similar issue. I can't rev my bike past 6000 rpm, and it idles very poorly. My headers on 1 and 4 are very hot, but 2 and 3 are only mildly hot. I originally thought it was an igition problem, (2 and 3 didnt seem to be firing consistently). I found a loose ground on my ignitor and after tightening it, that seemed to fix the inconsistant spark .... but I still have the same original symptoms (poor idle and a 6000 rpm ceiling). I just checked my compression on all 4 cylinders though and my compression is very low (like 60 psi). Not sure if that has something to do with it. Doesnt seem to make sense. I'd be interested in what you end up finding out with your bike though.

[John Kat]

A symptom like this typically relates to an ignition problem as cylinders 2 and 3 share the same coil.
Try running the engine with the spark plugs disconnected from one or both of these cylinders.
If the symptoms are the same you know where the problem comes from

[Missile99]

Big Red,

Did you stabilize the gas? 2 months means it's garbage unless you use non-ethanol fuel. Also the 4k rpm ceiling reminds me of missing pilot jet plugs. Are they in? If you haven't tuned the carbs, does that mean the mixture screws could be too rich? Also, yes, definitely get it running better before bothering with a carb sync. If all systems are good, it will scream to redline and idle good even without the carbs fully balanced.

I'm having a very similar issue. I can't rev my bike past 6000 rpm, and it idles very poorly. My headers on 1 and 4 are very hot, but 2 and 3 are only mildly hot. I originally thought it was an igition problem, (2 and 3 didnt seem to be firing consistently). I found a loose ground on my ignitor and after tightening it, that seemed to fix the inconsistant spark .... but I still have the same original symptoms (poor idle and a 6000 rpm ceiling). I just checked my compression on all 4 cylinders though and my compression is very low (like 60 psi). Not sure if that has something to do with it. Doesnt seem to make sense. I'd be interested in what you end up finding out with your bike though.

60 psi? Yikes. Let me guess, 276,542 miles on it. How close am I?
Seriously though, even without holding the throttle open on a cold engine it should be at least 100. Maybe the tester didn't seat completely on the head?
Something is strange here.

[Homie]

I'm with John Kat on this one. Smells like an ignition issue. I would swap coils and see if the problem swaps from 2-3 to 1-4. You don't have to physically "swap" the coils to do it. Just swap the primary leads (white and black (I think the other one is black?) wires and the spark plug wires. Fire it back up and see what happens. If the problem swaps you have a weak or inconsistent coil that will need to be replaced. The hardest part about doing this test is removing the tank so you can get to the coil leads.

[Big Red]

Ok so how would i go about swapping the coils. I am very new to this. do i switch the current going into the coils and leave everything else?

Also would having 2 and 3 to rich have this effect? I am going to try and thin them all up to see what happens tonight. i thined up #1 yesterday and foudn it fired prefectly but pipe got really hot while #4 was.
Is the pipe really hot a sign of to thin of a mixture?

i used the stabilizer and got some higher rpms and #3 seemed to fire better (got hot) but then next time i tried it back to normal.

Thanks again for all your help so far.

the goal is Spring 2013 on the road running perfectly.

[Hovmod]

I had 2 and 3 crap out on me last week, and it turned out that one of the ignition points had broken. The contact breaker thingy was just dangling off the end of the rocker, and came off when I touched it.
Never seen it before, but there you go.
Troubleshooting this isn't that hard.
Off with the tank, and follow the four wires from the two coils.

[Big Red]

I am still getting good spark on all plugs. If i take #1 and 2 out and ground both plugs to the engine bolck they both have the same spark alternating between them.

[heater63]

Big Red,

60 psi? Yikes. Let me guess, 276,542 miles on it. How close am I?
Seriously though, even without holding the throttle open on a cold engine it should be at least 100. Maybe the tester didn't seat completely on the head?
Something is strange here.

Actually it only has 9,000 miles on it. Crazy huh? I added like a tablespoon of oil to each cylinder and the compression shot up to like 120 psi on each cylinder. I agree, something doesn't seem quite right. I'm checking my valve clearance this week to see what those are at. That could be contributing to the issue too.

[John Kat]

The biggest secret to troubleshooting is to go down one alley at the time
The worst thing that can happen is to create new problems.
If cylinders 2 and 3 don't seem to work ( squirt some water on the exhaust pipes to check), you must first eliminate an ignition issue.
As Oldskool says switch the coils ( the 12V side but also the spark plug leads)
If it doesn't work any better you're not done yet with the ignition as the ignition points might be faulty ( or the condenser).
Fiddling with the mixture screw will not solve this issue especially if you can't rev above 6 K rpm

[Kaiser Sosei]

If it doesn't work any better you're not done yet with the ignition as the ignition points might be faulty ( or the condenser).

Looks like he has an '80 550, so no points or condensor. If swapping the coils doesn't fnd the problem you will need to investigate if the ignitor is working properly. The factory manual has directions on how to check the ignitor, it's fairly simple. Something on the order of grounding a wire and checking for spark.

A word of warning, the ignitor for the 550's are very hard to find replacements for. I belive someone on this forum was looking into building replacements, but don't know how far he got.


Edit to add linky:

http://www.thegsresources.com/_forum/showthread.php?t=182719

[Homie]

You don't have to physically "swap" the coils to do it. Just swap the primary leads (white and black (I think the other one is black?) wires and the spark plug wires.

OK, each coil has two primary (thin low voltage) wires and two secondary (high voltage) spark plug leads. There is a common orange or orange/white primary wire that goes to both coils to power them. Leave the orange wire alone. Its the other wire you want to swap. Next to the orange wire there is a white primary wire on one coil and a black (I think its black) primary wire on the other coil. These white and black wires come from your ignition unit (CDI or points). These are the ones you want to swap. When you swap them, you have to swap the secondary spark plug leads too in order to keep the firing order in place. Pull off the spark plug leads and swap them out putting the ones that were on 1-4 onto 2-3 and visa-versa. Now go give it a try and see what happens.

[Missile99]

Fiddling with the mixture screw will not solve this issue especially if you can't rev above 6 K rpm

My suggestion on the screws was to keep the plugs from getting sooty at warm-up if these were too rich. Good point on troubleshooting one thing at a time.

So Big Red, just how good is your spark and what color is it? Have you attempted swapping the coils as suggested? You may want to expose some fresh copper on the leads for good measure if this is stock stuff. Are both coils getting good voltage, say around 12?

Yes, too lean would be too hot.

[Big Red]

I have not had a chance to swap the coils yet. but as for the spark if i remember correct it is white/blue. the same on all plugs accross the board. While troubleshooting i drained the battery so needed a charge.

while running the starter testing the spark and other things how long should the battery last. I will put the multimeter through the system when i get a chance to see what the readings are when i am swapping the coils. (tonight?) Baby due in a week so i have some time off coming up to do some serious work time.

Oh ya and thanks for the info on swaping the coils. lets hope

[Missile99]

I'm wondering about this whole ignition issue. Do you have a timing light? It's what I used to see that my spark was weak at higher rpm or under load.

This whole thing reminds me of bad gas. Might be the 1-4 spark is a bit stronger to burn the mixture, just guessing. What color is the gas? Smell?

I don't know how long the battery should last for testing but I would assume after 20 or so start attempts I'd want to begin recharging.