Topic: 75 cb750f carb #4 backfire/ spitting fuel

[proudsnacks]

got the bike barely running, carbs were super filthy inside and out. i have been chasing an issue with this bike for months, thought it was the ignition advance, then i cleaned the carbs squeeky clean, got new float gasket to stop a drip from the #4 carb, drip didnt go away. i measured the float heights, all within spec at 26mm. i have also rebuilt carbs with new jets, o-rings, etc. stock sizes. The bike is all stock, air box, 4-1 factory exhaust. when i put the carbs back on without the airbox is when i noticed the #4 carb puffing and spitting fuel. the other 3 are sucking as they should. my research tells me that the float level is to low ad the pilot if sucking in air on the #4 carb. if the float level is to low, why is it dripping from the bottom vent hose? this is directly after separating the carbs and soaking for a solid 24hours. i got new intake rubbers, coils, plugs, plug wires, new points/ condensers. the only thing i changed was the muffler.
 i don't want a pickle, i just wanna ride my motorcycle

[jgger]

I would suggest checking the tapped adjustment at least on that cylinder's intake, and maybe a compression/leak down test. That's if you are certain the carbs/float/needle valve are all good in that carb.

[evinrude7]

Is the overflow pipe in the offending carb cracked?

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[sixthwisconsin]

I have measured float bowl levels very accurately and then measured by clear tube method only to find that I was WAY off. Check for cracks in the float tubes for sure but do yourself a favor and do the clear tube level check.

[flybox1]

^^^+1
Clear tube test the bowl fuel level to see what it REALLY is...
3mm below the top of the bowl is ideal.