FZS600 3rd cylinder refuses to fire.

[OhHowOriginal]

Evening guys and girls.
I've got a 2000 FZS600 and the 3rd cylinder simply won't fire.
I've exhausted my mechanical knowledge thus far and don't know what else to do.
So I've had the carbs off, unblocked all jets, completely cleaned all 4, they'd been balanced in my care by a garage prior to buying the bike back off a mate.
I've changed both coils, the HT leads and fresh plugs.
The compression across all 4 cylinders is within a tolerance of 10, around 175psi average.
There's spark on cylinder 3, but it's not super strong, although I would have thought enough to fire the cylinder up at least, but no.
I've put a new battery on today and still nothing.
I'm determined I'll fix it myself rather than just putting it into a garage (which I can't justify with an upcoming wedding anyway) but I'm not sure what else to check or try.
Can anyone recommend anything else to check please, I'm pulling my hair out going back and forth trying to figure it out.
Any help would be massively appreciated.

[Nobby the Bastard]

Typically a straight 4 is wasted spark so if cylinder 3 isnt firing and cylinder 2 is then it's not electrical unless...

either the gap on the spark plug is so small as to be no real spark or the HT lead is shorting on the engine.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Kawasaki Jimbo]

[OhHowOriginal]

[Nobby the Bastard]

Unless the spark plug cap is leaking electricity to the engine block it's not the cap.

It's easy to check, just swap the leads between 2 and 3. A 2000 bike isn't going to have a crossplane crank so firing timing is going to be the same for both.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[OhHowOriginal]

[OhHowOriginal]

[Nobby the Bastard]

In that case your problem is electrical.
Unless, of course, I'm completely wrong about it being wasted spark.

I'd look at the coil, leads etc. for 2 and 3.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[OhHowOriginal]

[stinkwheel]

Looking at parts lists, it's a single pickup ignition with three triggers on the rotor, one at TDC, one about 20 degrees or so round from it with the timing mark near it and a third at around 90 degrees so it may not be a straightforward wasted spark.


EDIT: No scrub that, it's a wasted spark, just checked a wiring diagram. Swapping the plug caps on 2 and 3 should make no difference on a normally functioning bike. Your problem is electrical.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Nobby the Bastard]

In that case ignore everything I said.

How many coils? If there is only 2 then don't disregard what I said.

Edit: The FZS is a follow on from the FZ and the FZR. Its wasted spark and if 2 is firing 3 should. if you swap the leads and it goes to fuck the problem is the leads/coil/plug/cap.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[OhHowOriginal]

I'll try again tomorrow when we get back from bowling with the kids.
So, from memory, coil 1 fires cyl1 and cyl3, and coil 2 fires cyl2 and cyl4, to test if its specifically the lead/cap/plug in cyl3, am I right in thinking I should swap it with cyl2 or cyl4?
If not, I'm happy to be corrected.
I also still have my old coil sets, I may try putting my old coil 2 onto the bike in place of coil 1 and see what happens.

[stinkwheel]

One of the coils does 1 and 4, the other coil does 2 and 3.

Each coil has a 12v supply in a black on red wire from the kill switch/safety interlock box. Since you are getting sparks on one, this could only be a problem where it splits between the two coils or connects to them. Check for overall condition and make sure there's 12V in both when the ignition is on.

Each coil has a single wire running to the CDI, one orange and one grey. Worth having a good look at the one that's supplying the suspect coil at each end checking for corrosion on the connectors and maybe doing a continuity and resistance test on that wire.

It's a fairly safe assumption that everything upstream of the CDI is ok based on it only having one pickup coil and it producing a spark. I say fairly safe because weird things can happen but it would need to be something oddball like a partial failure in the CDI or a damaged trigger bump on the rotor.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[jaffa90]

After running the engine for a bit is the said cyl/ spark plug wet with fuel or dry?

[that_impulse_guy]

going on from what stinkwheel said...if youre into diagnosis....the two wires going to the coil will be
1) one is permanently hot. 12v or thereabouts, when ignition is on.... Depending on bike and age of bike, this path may well go from battery, through ignition, through killswitch, to cdi..then from cdi to hot side of coil. ...any one of those items may well reduce the expected battery voltage (lets say 12.8v on a fresh battery), down by 1v or more...reducing spark power
2) second wire is ground, but not just any ground...its ground direct from the cdi...the cdi triggers this ground momentarily which causes the spark..

normally, cyl1+4 are together and fire at the same time, because its just one ground form the cdi to that coil thats getting momentarily interrupted by the cdi.
and then cyl2+3 is the other ground thats getting twiddled.

therefor, its totally possible to have the bike switched off, remove normal input wires from a coil.....run a 12v feed and a ground to the coil and manually twiddle the ground on and off to check for spark....effectively removing a lot of stuffs thats ordinarily in the way of getting a good spark.
and then you can work backwards from there...

before doing all of this, i tend to have the bike on but not idling or anything, just battery on, measure battery voltage, measure coil voltage, and then from there decide what Im gonna do..if theyre close, no need for the above tests...if theyre not close....then dive in.
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Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[OhHowOriginal]

Thanks for all the very helpful replies, if the weather is on my side I will do some more checking later on from everyones suggestions and report back.

[OhHowOriginal]

Update, so I've test all 4 sparks from all 4 HT leads, they're all strong and equal, I've changed the coil for cyl2 and 3 and it's sparking great now.
I put quite a lot of fuel down the barrel (out of frustration if I'm honest) and all 4 cylinders ran for a few seconds then cylinder 3 stopped again, so I did it again and the same thing... I'm thinking it's carb related, despite having had them off... Should I have them off again or is there somewhere else fuel could be getting stuck to just 1 cylinder?
Again, I really appreciate everyone's replies.
On another small note, I've just tried to tax the bike ready for MOT and it says I can't tax it without an MOT, so am I legal to ride it to the garage for an MOT and should it still pass on 3 cylinders?

[Easy-X]

If you have an MoT appointment you're entitled to ride there without an MoT (or tax) but you do need insurance.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[A100man]

[OhHowOriginal]

I'm insured so that's great, she's booked in today at 1pm.

I've got carb cleaner so I'll give that a try before removing them again.
Is it best to squirt some down prior to starting or when the bikes already running?

[Kawasaki Jimbo]

[OhHowOriginal]

It did indeed pass,got one advisory for a warped front disk.
I have tried carb cleaner in carb 3, still won't fire into life, any mobile mechanics fancy coming and having a look, in the Warcop area?

[A100man]

Can you run it in the dark to check for arcing on #3 ignition leads/cap?
I guess you might have to set-up a remote fuel tank.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[OhHowOriginal]

[OhHowOriginal]

In my majesty today I've pulled the carbs off again.
I've noticed number 3 is dirty.
The other 3 aren't, even though that was clean when I put them back on last time.