Carb overflow

[BanditPervert]

Finally started the bike yesterday and ran lovely for around 30 seconds, sounded great raving up and down to 3/4 throttle. 
 

Turned it off and fuel pissed out the turbo outlet, pulled carbs and cylinder 1 full of fuel and 2,3 and 4 were a little wet on the inlet rubbers. 
 

when I started it, I let the oil pump run for 30 seconds, switched on fuel pump, just below 2psi from gauge, and then started the bike. I have the floats at 16mm, the vents pressurised from the pilot tube on the charge pipe, and the fpr fed from one of the carb tops.

im guessing that the float on number 1 was not seating correctly but not sure why the others were wet.

any advice would be greatly appreciated. 
 

thanks 

[clivegto]

What pressure did you set the fpr at when running. I have mine at around 1.5+psi. Does sound like ike  no 1 float valve has a problem as well. 

Edited May 18, 2021 by clivegto

[BanditPervert]

Was just under 2psi, didn’t think that would be enough to overcome the tabs though 

[Gixer1460]

Is the float ht. std or 'adjusted'? Obviously carbs are designed to seal only with gravity fuel pressure and any added pressure over that could be too much - i'd be tempted to back it off to 1psi or less? The boost added to the bowls and the FPR should keep it balanced.

[Maggotbreath]

Float valve O rings new or maybe pinched?

[TonyGee]

the float valve seat O rings can harden over time and crack, when they do it gives the same symptoms as a float valve not sealing.  

[BanditPervert]

The floats and o rings are about 3 months old, they have been sat in there with no fuel for that time.

[BanditPervert]

23 hours ago, Gixer1460 said:

Is the float ht. std or 'adjusted'? Obviously carbs are designed to seal only with gravity fuel pressure and any added pressure over that could be too much - i'd be tempted to back it off to 1psi or less? The boost added to the bowls and the FPR should keep it balanced.

Where does the 1 to 2 psi come from originally, is there a sweet spot to aim for or just low enough for the float tabs to handle?

[MeanBean49]

36 minutes ago, BanditPervert said:

Where does the 1 to 2 psi come from originally, is there a sweet spot to aim for or just low enough for the float tabs to handle?

As low as you can get really.

May be worth checking your fpr is plumbed up correctly, you can get it the wrong way round so you can set base pressure but when running it will let pressure go far too high amd flood carbs

[BanditPervert]

I’m positive it’s connected correctly, i cut a single coil off the spring and got down to 2 so could snip a bit more off and get to 1. I guess every little helps but didn’t think it would be an issue at 2 

[MeanBean49]

32 minutes ago, BanditPervert said:

I’m positive it’s connected correctly, i cut a single coil off the spring and got down to 2 so could snip a bit more off and get to 1. I guess every little helps but didn’t think it would be an issue at 2 

Shouldnt really be a problem at 2 which is why I would also be inclined to check everything else as well

[colinworth79]

You don't mention the return to the tank?  Needs to be bigger bore than the feed pipe and must be above the fuel level. On my bandit 12 I removed the fuel sender and made a plate. 

Fpr I took off off the plenum but it's not going to affect anything at low revs like the problem you have at the moment.