vfr nc21 only firing on three

[arsey30]

I know we all have to learn about things we have not seen before, that is why I am trying to help.

It is not your typing confusing me but your terms.

The tap "overflow" is the breather and no fuel should flow from there, if it does, it will pour over the engine when the engine is running, but not enter it or the carb. Sounds like a split diaphragm.
The taps come apart [at least the nc30 ones do] so remove the diaphragm and hold it against a bright light to check for holes or split, but if leaking that much, a tear will be obvious.

The jets screw into the bottom of the carb within the float bowl. Not sure what "slits" are unless you mean screw driver slots, but all jets a screwed in tight.

The pilot screws are in the sides of the carb, not in the float bowl.

The reason I said leave the tank over night is to check for small seepage that would flood engine over a long period of time if left.

[arsey30]

The screws and jets can each be removed in any order, but note where each comes from as main jets and sometimes emulsion jets are different in front and rear carbs.

However, do not remove them or the pilot screws, as they have nothing to do with flooding.
Screw pilots screws in until they lightly touch the seat, counting the number of turns as you go.
They should be 2 turns out from fully in, so set them at that.

What are these jet slits?

[deno98]

pilot screws where set wrong

[deno98]

you where right jet slits were screw driver slots thank you so much think i might of fixed it now pilot screw was at 5 turns out on one carb ajusting to 2.25 as bike has scorpion can
would petrol not come out if tank tap was in on postition even if there was a slit in diaphragm?

[arsey30]

Pilot screws have nothing to do with flooding, but best set right.

A quick look in the tap will solve it, fuel should only flow from the main outlet.

If the tap is the same as nc30, there are 2 diaphragms, the outer is vacuum operated and pulls the inner one that shuts off the fuel.
If the outer is OK the tap will work, if the inner is split it will leak out of the breather with engine running [vacuum applied] but not out of the main outlet with no vacuum applied.

[deno98]

on it i think thanks again checking tap now if i plug breater hole would this be bad or ok

[CMSMJ1]

With the effort you ahve already put into sorting this and being closer to getting it proeprly sorted, I would not be looking to just bodge a fix.

If the tap is knackered, then a new tap (or a good second hand one) would be the way forwards.

Blocking up the breather is not going to stop the fuel seeping out the tap - your bike will stink of fuel and at the end of the day, for the cost of a few beers on the town, you'll have it sorted properly.

[arsey30]

That's right, and replacement diaphragms do not seem to be sold seperately.

I can't work out how the leak was not obvious when the bike was started and ridden, it would smell of petrol even if it did not run down and was visible.

Was the vacuum hose on the correct spout in the first place, i.e. the vacuum spout and not the breather spout.
If not, that would account for fuel in the engine, although the flow to the carbs would have been low .
Was the flooded cylinder the one with the vacuum hose connexion.

[Neosophist]

The pilot screw cannot be at 5 turns out either else it would be fallen out.

Are you counting a full turn or a half turn.. I think you are counting 1/2 turns which means it was actually 2.5 turns out which is about right.

Easy way to tell is put a ink dot on the screw-driver handle and turn the screwdriver until the dot is in the same place again (1 complete turn)

Your fuel tap is leaking.. it sounds like the diaphram is busted as arsey30 said.

The VFR is quite a complicated bike to work on.

You need to have the carbs properly set-up and fix the fuel-tap.

[deno98]

right firing on all for again carbs set right runing best it has fuel tap is leaking have site for kit or might buy second haand tap
no oil leaking at all but blowing abit of smoke when hot oil dip stick just over full line when hot so gonna try drain some oil out and arsey yes vacuum pipe on failed pot and attached to breather think im nearly there now tho fingers crossed thank u all for all your help