1978 gs550 firing problems

[lzamora78gs55...]

Looking for some help on finding out why 1 and 2 (Exhaust pipe cold to the touch) not firing, 3 and 4 pipes are hot to touch. Looking at the wiring diagrams, Left coil (1 and 4), right coil (2 and 3) soil coils are working?

Thanks,

[to v or not to v]

check the condition of the spark plug leads. they could be damaged and arcing out somewhere before the spark gets to the plug.
happened on my gsx550.

[bikenut]

Much "chuffing" going on with the engine breather and equal compressions when turned over by hand ? Just cannot remember if this bike has a kick starter, too lazy to check on CMSNL, will perk up after breakfast though 😊
There may not be much evidence from the breather ( one up one down equals same ).

If you have a compression tester ( even your thumb or a tapered broom handle ) use it and check plugs at the same time.

If all compressions ok say thank you God, then move on to carbs.

Neons are real handy for stuff like this.

Ah, breakfast has arrived, yum yum, thank you dear...
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nuts about bikes

[oilrag]

Are the plug wires on 1 and 2 on the wrong cylinders?

[jaffa90]

"""why 1 and 2 (Exhaust pipe cold to the touch) not firing,""

How do you know they are not firing?

The exhaust / silencer on that side could be blocked!
Also are 1+2 carbs getting fuel?

[bikenut]

This is why those red neon plug caps are so handy.

If they flash then some HT is passing thru.
If they flash more brightly then more than some HT is passing thru.

Compare flash intensity with a good cylinder, a little feable at cranking and same on other cylind rs, but the engine starts, so enough HT to make engine run.

Flashes are much brighter at idle and grow much brighter again with revs, good cos rate of change has increased, but then flashes disappear, bad, that cylinder with the he missing flash has an ignition problem.

Yes they are not the be all and end all as they will flash if the plug is being "cat" like.

Cat like ?

What do cats eat ?

More dribble I hear some say, some are laughing eyes out !

So what does cat food have to do with spark plugs ?

I can hear pennies drop ping from here......😊
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[Nobby the Bastard]

[bikenut]

As above, strong possibility, but will the leads reach ? Do the leads have numbers, and is the owner dum
enough.......anything is possible, any backfiring....

It's so satisfying to rule one thing out, or in....... you r strip the carbs take the exhaust off or find some squatter in the Carbs or intakes.

Rule one thing in or out, easy with the neons......rule ignition in or out as a starting point, draining carbs is also good, looking for crap/water, and fuel flow.......I go for ignition first then move on...why, cos it's easy.
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[steve the grease]

Before ripping the exhausts off or stripping the carbs , just check the plug leads. to 1 and 2, it's so easy to get them the wrong way round, if you've been in there.
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All the above is my personal opinion, you can see my lips move, but I'm talking out of my arse.
I've been riding, and fixing , bikes for 50 years, in that time the more I learn, the less I am absolutely sure of.....

[jaffa90]

[bikenut]

Hi Jaffa, predictive text ? Htf is it turned off on an Alcatel phone ? Anyone know please...
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nuts about bikes

[Nobby the Bastard]

[lzamora78gs55...]

Thanks for all of the hints..

since coils seem old-buying new ones as well as replacing spark plugs at the same time.

I just finished re-jetting the mains due to air pods and exhaust mods, on start-up I noticed that 1 and 2 pipes cold, 3 and 4 hot,,wiring diagram does not indicate which side of each coil goes to 1 and 2 simply that left coil goes to 1 and 4 and right coil goes 2 and 3..coils coming tomorrow so..

[Nobby the Bastard]

[bikenut]

Do you have a wiring diagram and are you colour blind ?

Fair question I feel as we now know you have been altering stuff on this bike.

Post a link to CMSNL for your exact bike so we are all looking at the same exact bike...
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nuts about bikes

[A100man]

[lzamora78gs55...]

She's fully running...here is the latest:

1. Removed and rebuilt all jets, and float needles. Washed out all passages. (much garbage, she sat for a while so gas solidified)
2. Replaced mains from 80 to 100, left pilots at 50 (compensate for pods and open exhaust)
3. Replaced both coils and installed new plug connectors (old and crusty)
4. Replaced all plugs with new NGKs (common sense)
5. Pods are allowing too much air so sealed about 90% of surface on each pod, will need to change out pods to seal better (Uni, or KandN)
6. running with no choke needed
7. Added baffles to exhaust pipes (quieter, no ear plugs required)
next steps:
carb sync and check for lean/rich conditions and adjust as required.

thanks for all of the great feedback..

[Britabroad]