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Question Misfire at low revs

BButch

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G’day all!!
Would appreciate some thoughts on a fault I’m working on…
I just purchased this FZ6, 08, from auction, crashed 🤠
Headlight, Speedo, ignition barrel, immobiliser etc all gone, smashed off. Just severed wires where it all was really. Sound good?! 😂
Then I took a punt on China and threw some AliExpress items at it like an ignition barrel set, immobiliser emulator, (a heap of other bits too) to be somewhere near trying to start the engine…
I eventually got it running. (Amazed)

Took it for a test ride with its nicely bent handle bars, it was misfiring intermittently.
Mostly at low rpm. But pretty bad.
Fuel smelt ok but I pulled the tank off and pump out, and got some water out of the fuel tank, 100-200ml or so.
I was sure this would be the issue!!
Refit tank, fresh fuel, fuel system cleaner additive in, optimistic test ride, fault remains the same. Still misfiring.

Pulled coils, leads and plugs.
No observed obvious problem with plugs, coils both have same resistance across terminals.
Leads and caps resistance readings were not very conclusive, eventually on third multimeter I could get roughly 9.5 ohms on 3 of them, I struggled to get a reliable reading out of no1 cap, (which had white powdery deposits in it, suss) but eventually I sometimes got a similar reading out of it.
Gave everything a really good clean up, reassemble, much better!
Still misfires at take off more often than not, but it is improved slightly, and although isn’t perfect elsewhere, it’s much better.

So!!
I’m leaning towards replacing the caps and plugs minimum, perhaps the whole lot depending on price.
And I would much appreciate any recommendations of parts/suppliers ( I’m in Western Australia), or if you think I should do something else!!
Cheers!!!!🍻
 
Welcome to our great forum and G'day mate!
Coils can be tricky. It sounds like you're on the right track with the secondary focus. You might also check and redress the secondary connection to the spark plug assemblies.
A compression check on the offending cylinder might also be in order.
 
I'd suggest running it and checking the temperature of the header pipes.

If one of them is colder than the others, that will probably be the one misfiring.

If so, try swapping the plug leads from 1 and 4 to 2 and 3 and see if the colder header pipe moves which would point to a problem with the coils or HT leads.

BTW from the damage you describe, I'd check the headset and frame for damage/ cracks etc before you ride it again!
 
Thanks for the feedback lads, much appreciated, hope to respond soon with updates but I have done nothing further yet…
The frame seems fine, looks ok, rides well. But it does creak and crack a bit when compressing the front suspension, (whilst stationary) are the forks known for being a bit noisy like that??
 
it does creak and crack a bit when compressing the front suspension, (whilst stationary) are the forks known for being a bit noisy like that??
Definitely not!

I would strongly recommend a complete strip down and check...
 
The FZ6 frame is actually left and right hand sides that are bolted to the engine and come together at the head stock. I would check the bolts on the head stock to confirm that they aren’t loose or worse, cracked from the prior accident.

Another thing to check would be the upper and lower steering shaft bearing to confirm that they were not damaged in the accident.

Lastly, I would disassemble the forks to confirm that the fork tubes aren’t bent by rolling them on a flat surface.
 
G’day all!
Thanks for the feedback, just wanted to give an update.
Not sure how, but the creaking fork issue disappeared 🤷‍♂️
The misfire update…
Misfire fixed!
It was the coil pack for cyl 1/4
Replaced with a cheap aftermarket set off eBay and it fixed it 100%
For 2 rides 😂
Then unbelievably the fault returned, same cylinder (1). I was starting to second guess the fix but I had such a strong feeling it was coil again, so I put the OEM coil for cyl 2/3 back in and put the after market one that was on 2/3 onto 1/4.
Fixed again.
Running perfectly.
For now.
Actually managed to get it licensed yesterday too!
Thanks for your input everyone
 
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