Pin holes in floats

[91octane]

hey everyone, new member here. just wondering how common it is to have holes in floats? bought a 1980 cb750k and im getting around to rebuilding the carburetors and found that all four floats have pin holes in them. I suppose i could have screwed them up by throwing them into hot water. I have a small ultrasonic cleaner and i boiled out one carburetor, the cleaning solution was at around 130° and i dipped the floats in it and found all four had a pin hole in the same spot. I cant believe how much they want for new floats, plus carb kits, and accelerator pump kit. anyone have any experience with aftermarket floats? or experience bypassing the air cut off valves? I saw a trick with blocking the o-ring in the cut off valves and turning the pilot out to make it a little richer.

 

[amc49]

If holes on bottom then if bike sat with ethanol laced fuel the ethanol pulled in water to corrode the holes in.

Later floats are entirely plastic but they cannot be adjusted for that fact.

The air cut mod works fine. You have to include the main cover gasket and the valve is left in place as well to block the second idle air passage. The cuts only stop afterburning in pipe that makes backfire at deceleration.

 

[91octane]

thanks amc, i dont know the history of the bike but with living in iowa they try and put ethanol in every grade of fuel. they dont have to mark it as containing ethanol until it reaches 10%. my floats are all plastic and it looks like its a very fine crack at the bottom of the float. guess ill have to buy all new ones.

i had another question when i pulled the plugs both outside cylinders were burning richer than the inside, now that could be a carb adjustment but what i noticed is that both outside plugs are controlled by one coil and both inside plug are controlled by the other. the coil controlling the outside plugs has cracks in the plastic casing and both primary outputs where the plug wires meet the coil were growing green corrosion. do you think that coil is bad? ill try and post some pictures once i figure out how.

 

[91octane]

will submersing the floats in hot water force a leak that wont normally be there?

 

[amc49]

Can't say that would show anything but I might be full of crap too. Never had any issues with floats before. More like the super fine rust getting through any filter you use to then mess up the needle from sealing. NOT a float issue. The ethanol tends to make needles stick as well if bike sits say a couple weeks.

May only need to clean corrosion off contacts where wires touch. Cracks in coil casing are not good though. Anytime I see that the coil is suspect. Focus cars now use bike type like these and cracks on them are guaranteed bad, moisture then gets in to short out part of the field windings then you get less spark. Same with all coils.

FYI, valve guides get hot and hard to leak oil pretty easy on these and even worse if they have been renewed as the aftermarket ones are nowhere near as good as the OEM were. The Vesrah or Athena seals suck, and go hard in a year or less. I mention seals because they will often darken the plugs like too much fuel.

 

[91octane]

thanks amc, im just trying to figure if i need new floats or if it was leaking past because i submersed them in hot water causing the air inside the float to expand and find a way out. here is a pic of the coil. it very well could be the valve guides thats next anyway but i thought it was odd that the coil with the cracking and corrosion was the one controlling the two outside cylinder plugs that were black and the two inside were cardboard brown.

 

[91octane]

thanks again amc, your a big asset to this site.