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Dellorto Float Bowl Leak

RPGR90s

Member
I'm trying to solve an issue with only one Dellorto on my R90s.

For some reason, only the left side float bowl leaks/drips at the nut. I'm using the stock 21mm gasket and nut.

I've tried three different gaskets, and all of the surfaces are clean.

Maybe next step is applying some fuel resistant gasket material but thought I would ask here first.

Thanks,

(90) 21 mm Float Bowl Nut for Dellorto PHM carburetor 10238.jpg(89) 21 mm Float Bowl Nut Seal for Dellorto PHM carburetor 2778.jpg
 
When I have a persistent leak, I always start to wonder if the leak actually originates where the fluid appears or if it actually starts somewhere else.
 
When I have a persistent leak, I always start to wonder if the leak actually originates where the fluid appears or if it actually starts somewhere else.

Ditto. Might be worth trying the oil leak trick -- clean everything off, spray the carb with a hing aluminum oxide content deordorant (I like Arid xx dry) then turning the fuel taps back on. You should see tracks from where the leak is.

Otherwise, something is keeping the plug from fully seating. Could be something on the threads on the bowl.
 
I went through my Dellorto parts and found an early style float bowl (Float bowl nut is smaller) and installed the bowl with the older nut and new gasket. Rode about 100 miles yesterday and the problem is solved.

Man, I need to ride the R90s more. Just does everything an old classic bike should do, and very well.
 
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