Carbies willn't set float level,right floods,left sets to low

If the carburetor is flooding it is the needle and seat under the float in the float chamber that is either stuck, leaking (a bit of dirt caught in the seat) or the float level has changed or the float is leaking. Any one of these faults is cause for removing the top cover of the float chamber to investigate and repair the problem. (A crack in the housing cannot be ruled out although unlikely).

incorrect float level setting
needle and seat not properly installed
try having the carby professionally overhauled

That's because it's complicated if you don't know what you are doing...the site below, although from a 600, shows the carbies in all their glory. Your carbies are just a smaller sized throat.

What you have to do is balance the carbies. From throttle stop, needle clip height, air mixture screw settings, same jet sizes throughout all 4, and float bowls set the same. All are simply but fiddly and time consuming.
Take airfilter manifold off and look into all four carb's to see if all slides rise and fall in complete unison when winding throttle. Check choke linkages for slop.
Try spraying some CARBY CLEANER down fuel line till fluid exits all four carby drain plugs. float needle/seats and jets may simply be dirty.
Check condition of all fuel lines for bunching or cracking at the clamps. Replace fuel filters if required.
Cheers.
http://www.cmsnl.com/yamaha-fzr600rfc-1994_model10057/partslist/B-08.html

Float tabs come set flat to surrounding plate, bend up to decrease level and down to raise level. Raised level too much and you risk fuel overflow on sustained inclines and too low a level and you will lean out at high revs and damage valves/piston real quick. There is no set level to speak of, but better to err on the side of losing a bit of overflow. The overflow drains from the carby via a plastic hose from just above float bowl flange.
Cheers.

sounds like the float level is set to high and it is laeking out the over flow. try adjusting float level.

It sounds like during the rebuild the float level some how was changed to a higher setting. There is a tab on the float that needs to be bent in order to change when the float valve actually closes. Seems your float valve adjustment is allowing the carb fuel level to be too high which will create the exact symptom that you described.
If the level is fine then there can be a small piece of debris in the float valve seat.
Also.. if the float itself has filled with fuel it can be too heavy to float and cause the float level position to remain low even when the carb is full not allowing the fuel supply to be shut off. If the new o-ring for the float valve was cut during installation it can also cause your current symptom.
At this point I just think that a float level adjustment is all that should be required.
with the float bowl screws loose the bowl should never overflow in a static condition. If it does the float level adjustment is off.

Thanks for using FixYa.

Kelly

If spark plug is wet with petrol then float level is incorrect either by dirt under float needle or set too high.

If you havent altered / removed the carb and it has just happened, somtimes gently tapping the float bowl can dislodge the dirt. Otherwise you will need to remove carby, (I assume it has one) and clean out.

It would appear that the Black smoke is unburnt fuel, meaning Spark or timing could also be out. Check you plug and point gaps. If you rebuilt the carby, float level is crucial also check the needle and set to ensure it is shutting off the fuel, if it is not shutting off, it will just flood the engine. Not sure what carby you have but I woud pull out the jets/power valve and replace them. Some carbys have a small ball bearing to control fuel, if that was lost that could be it. Pull up an exploded diagram of the carby and do it again. I know its time consuming, but it will be peace of mind. Good luck

the floats may be damaged
try to level the floats with the base of the top part of the carby and see how you go .
you may have to try a few times until you get it right .
Check your needle point too as it may be stuck as well .

Sounds like the carby is flooding.

Have you had it off?

Try putting a new fuel shutoff valve and seat in.

Set the proper float level.

Make sure that the float does not have a hole in it that makes it sink.