Mikuni problem

[Chris Launders]

Has anyone had the same problem as me, I have a pair of mikuni's on my norvin which I've only used a handfull of times this year but I've had one carb flood three times and the other twice, last night I had it drop on to one about 5 miles from home.
Examination this morning has shown up that there is no clearance between the float arms and the pillars they pivot between and is actually nipping the arms slightly, enough to make the arms stiff to move on BOTH carbs.
I've filed a few thou off the arms and they now move freely, is this a result of ethanol swelling the brass or aluminium ? I mean what else could affect them given they are inside and they are not in any way gummed up.
Chris.

 

[ClassicBiker]

I've had Mikunis on my Shadow for years and not had this particular problem. I tend to also to put Stabil (a brand of fuel stabilizer) in my tank regularly. I doubt the brass or aluminum is swelling, because that would suggest that the metal is absorbent. However what I wouldn't be surprised to learn is the ethanol is attracting water out of the air and this is causing corrosion to form on either the carb body or the float. This build of corrosion could cause the binding you are referring too. I also wouldn't be surprised to find that the ethanol is attacking other components in the fuel system and causing them to break down and this is being deposited in your trouble spot or on the float spindle and causing the binding and your dismantling to file the pillars to create clearance is freeing up the spindle again.
My suggestion would be to use fuel stabilizer and fuel system cleaner as a prophylactic to the carbs gumming up.
Steven

 

[Chris Launders]

There was no corrosion or gumming up, the float chambers are spotless and the float arms were simply tight between the pillars but not on the spindles ?
I filed the sides of the brass float arms and left the pillars alone .
Chris

 

[Robert Watson]

I have found, as have others, that sometimes the holes in the floats are too tight on the little rods they slide up and down on causing them to bind. Using number drills by hand I just eased the holes very slightly. Problem solved.

 

[Chris Launders]

Hi Robert, it wasn't the floats but the arms themselves, when I took off the rear float chamber the arm stayed up keeping the valve closed, the floats stayed in the bottom section.
Chris.