post carb rebuild idles find dies under load

[Goetz]

Just finished rebuilding the carbs. Bike will now idle just fine w/ choke untill warm, and then idles just fine w/o choke. tries to die instantly under any kind of load. synch issue? air mix screws set at 4 turns now, floats set at ~.90 in, im at a loss. new intake o rings installed. again, idles like a champ.

[Pat Conlon]

Explain what you mean by 'rebuilt' ....did you clean the pilots and all the little holes in the needle jet nozzles?(aka emulsion tubes)
4 turns out sounds rather fat for the air idle screws. Try leaning it out to 3 turns...
Is your tank clean? Fuel lines clean?..

Sounds like your idle circuit is working ok....You can sync your carbs now the your bike idles...

[Goetz]

rebuilt as in 4 complete kits from randy. Brand new EVERYTHING. needle valve seats, needles, e tubes, main jets, pilots etc. Diaphragms sound, needles at 2nd clip from top, fuel linesflushed, ill check for debris in the morning. I may have measured the wrong way for float height, and that could cause this i suppose. It acts like its running out of gas under load till just about WOT and then it has power. Uni pods and a kerker 4 into 2.

[racerrad8]

Just finished rebuilding the carbs. Bike will now idle just fine w/ choke untill warm, and then idles just fine w/o choke. tries to die instantly under any kind of load. synch issue? air mix screws set at 4 turns now, floats set at ~.90 in, im at a loss. new intake o rings installed. again, idles like a champ.

Is the measurement from the gasket surface or raised flange? The are supposed to be 22mm (7/8" or .875) from the gasket surface. If you are at .900 at the gasket surface you at .025 too low, if from the raised flange, you are significantly too low.

If they are that low, it will have several issues...

Randy - RPM

[Goetz]

gasket surface, w/o gasket, and it may be even higher than that as i measured them horizontal, though the needle springs were not compressed... at least i can synch it tomorrow. I will lower the floats. should i change needle clip position to 3? I would rather not as thats got to be the most time consuming aspect, getting into those slides...
however, at least now i get to use hex bits. 

[Goetz]

...sigh. woke up at 3:30 this am. now have the carbs off the bike again. setting correct float height. heres hoping i get to freeze my butt off on the way to work, im sick of the cage.

[Goetz]

....aaaaaand so.
all float height had been set to .99~1.13 in. Now they are set to .875. time for a bench sync and a cup of coffee

[Goetz]

  :dash2:well, its not the floats 
Now, the e tubes i got in the rebuild kid were not shrouded, should this make a difference? and the float valve needles were the large ones. everything is cleaned and lubed it just wont go. open to suggestions. or donations, those rebuild kits aint cheap

[Goetz]

www.3cyl.com/mraxl/manuals/carbtune/carbtune.htm#circuitswww.3cyl.com/mraxl/manuals/carbtune/carbtune.htm#circuits 
Makes me think its gotta be the pilot, and maybe needle circuits, gonna tear em all down again after work i guess. Put the needles at 4 and triple check the pilots. All the slides held vacuum. If anyone has any other ideas id be greatful.

[SlowOldGuy]

Just a shot in the dark, but it seem like you're uncovering the idle jets.  Since you just checked teh float height, try cehcking the fuel level directly by attaching a clear tube to the drain screw.  Open the drain screw and check the fuel level relative tot he float bowl gasket line.

Next, verify that you're flowing enough fuel.  If the fuel delivery is not able to keep up with demand then it will id le fine, but act like it's running out of fuel under load while you're on the needle circuit.  However, if you give it enough throttle to transition to the main jet, it will pick back up.  The reason is that the idle jet sits a lot higher in the float bowl and if you have a fuel delivery problem it will starve first.  But, the main jet is much lower in the float bowl and usually there's still enough fuel in the float bowl that it will continue to run for a little while.

Sorry, just guessing here.

DavidR.

[Pat Conlon]

Now, the e tubes i got in the rebuild kid were not shrouded, should this make a difference?

The unshrouded e tubes are correct for your '85, unless you (or the PO) have the later year FJ carbs installed.
Did the e-tubes you took out have the shroud?

[Goetz]

To pat, yes they did
Re float height
I have bent the little Tangs up past level, towardsthe apex of the bowl, at .88 i think it sbould Be fine but willcheck w tube. The fuel should come j7st to thegasket, yes?

[Goetz]

Im sure the parts are fine, its the mechanic thatworries me...

[SlowOldGuy]

'85 is supposed to have shrouded e-tubes (mine are).  '84 is the only year with unshrouded tubes.

Could be the combination of unshrouded tubes with the slide cut-away causing problems.  Can you re-install the old tubes?

DavidR.

[Pat Conlon]

Ok thanks David, I thought the 84/85's were the same.....yea, clean and install your old e-tubes.