Firing on 3 Cylinders

[.Bishbash.]

OK this bike is doing my nut in. It's a VFR400 NC24 (cue Robbie for a disliking reply on NC24s).

OK Dom and myself have tried everything we know to get this going.

What we've done so far;

Ensured all plugs/colis are working
Fuel is getting to the carbs
We cleaned the carbs out, all jets are clear

Cylinder one is the problematic cylinder. It does fire, but only if you cover the air inlet trumpet to the No.1 inlet. Then after a few seconds goes back to firing on 3.

Now it has worked in the past and has only stopped working by being sat for about 5 months. Would have thought the carbs to be the problem, but nothing is blocked.

Any help would be hugely appreciated.

Thanks
Neil
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Current bike - GSX-R1000 k8

[Pete.]

If you have a spark then it's either fuel or compression related. If it worked before being stood-up but now doesn't that rules out compression so get the carbs apart again.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[.Bishbash.]

You reckon? What to look out for? it was spotless in there and everything seemed fine.

Would getting them balanced help at all?
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Current bike - GSX-R1000 k8

[Casper]

there is a channel that the fuel goes up when on choke. stick a strand of wire up to make sure this is clear. Take out the main jet and washer, take the top apart and out with the slider and needle. the brass part that the main jet came out of, stick a bit of soft wood like a pencil over it and tap it out. make sure all the holes in this cylinder are clear. Get a tin of compressed air from a computer shop (This Asda sells it) and blast this up all vents. I have a PDF that explains what direction the fuel takes at different levels. Its different carbs to yours but gives you an idea. If you want it mail me at rolfe66@gmail.com , Its to big to add as an attachment to this post. I had the same problem and cleaned the carbs many a time, at the end of the day i kepped missing a part when cleaning.

Oh, there is also a mesh under the float needle, take needle out and check the mesh is not blocked, it should pull out with a pair of nose pliers.

Good luck

[Pete.]

[Pete.]

I cut the relevant pages from the PDF and attached them here. Should make it very easy to understand the operation of carbs at various stages of throttle opening:
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Casper]

[Pete.]

I use PDFill. It installs as a printer, so you just open anything that you could normally print but select the PDFill virtual printer and instead of spitting out paper it generates a PDF.

To print part of a pdf, just go to print it as normal then specify the pages you want. Change the PDFill printer properties to black & white and turn down the DPI to reduce file size.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Casper]

Cheers Pete. Works perfect