92 Honda CB400 SF NC31 Carburettor settings

[Superjack44]

l have been having problems with my 92 Superfour l think it's all down to ethanol in the fuel the bike just would not run like it used to, the fuel economy is poor too.
The carbs have been stripped and cleaned but still poor running the carbs would flood too l stripped them again checked the float s and found that the needle valves appeared to to be missing that small spring inside as there is no feel of springing when the float is pushed up against the valve it's the same on all four valves , they just don't appear to have any spring effect when the float is pushed up against it, it's the same when the carbs are off the bike turned upside down remove the bowls and the weight of the floats just press down on the valve seats with no spring back in evidence, l have ordered new ones but what l would like to know is when fitting new air mixture screws the small rubber o'ring, steel washer, and spring how far in is the screw screwed before turning back 1.5- 2 turns out.
Also when first turning the screw in is the screw turned in far enough to bottom out on the seat or is it screwed just far enough in to sit on the rubber O'ring before turning it back out 1.5- 2 turns. Jack

[magg]

Without spring action doubt float level can be set correcly. Idle mixture screws shound be screwed fully in and then backed out the turns required.

[Superjack44]

Thanks for getting back to me.
What l want to know is when fully screwing that idle mixture screw fully in does it just just sit on the small o'ring or does it screw past the centre of the o'ring and sit on the screw seat.
So that when adjusting the idle mixture screw it is being screwed off/out from the o'ring or off the idle screw metal seat.?

[Superjack44]

The carbs l took off there is no spring action on the floats , when holding the carbs upside down the floats fall to what is the top of the float chamber and l do believe that E10 petrol is to blame for the current problems they seem to have damaged the petrol needle valve internal springs all 4 needle valves appear to be not working.
l have new jets and needle valves to go in l just need to know how far out to screw the mixture screw from where the screw sits either on top of the o'ring or where it sits on the metal seat under the o'ring

[magg]

Assemble spring, washer and o ring onto mixture screw in that order. O ring seals the mixture screw in the bore of the hole. The washer stops the spring from tearing into the 0 ring. Screw mixture screw into carburetor until it lightly bottoms and then back the screw out the specified number of turns. The mixture is set by the distance the taper of the mixture scre taper extends into the passage in the carburetor.

[Superjack44]

Many thanks for that information it's greatly appreciated Jack.