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twin hs2 on 998 cooper manifold and std airbox..

new floats ,gaskets,shut off valve assemblies (from a supposed reputable source)
carbs stripped ,so clean as new,,,
electric std pump...as per all mk1

inline filter pre pump
inline filter post pump

for no reason,,and at regular random intervals..one of the carb tops floods without warning

this is dangerous,,,

why is it doing this,,the fuel system is spotlessly clean and filtered,,no grit is entering float chambers

take off float lid,,,blow through it,,and inspect all is ok

few start ups later,,it does it again...

im ready for taking a sledgehammer to it...

can anybody shed a light on this?

small fibre washer required under the shut off valve, this would lower the fuel level in the float chamber.

Old indian trick my boss carried out for me back in the distant past when i was running an old 1" 3/4.

It would do the same thing as you mentioned.

ive just bought some modified superflow valves,,these come with a fibre washer too

anybody else used these?

had similar problem,with my single carb,to the point i was loosing my patience with it,bought a stay up float kit from burrel and fitted a good quality in line filter directly at the float chamber,I was told to fit this kit and forget. The advice was spot on never had another bit of trouble with it

Had a similar problem, turned out it was leaking from where the fuel pipe connects on to the float chamber.

Very hard to trace the leak as I thought it was coming out of the float chamber.

I changed the new Smiths type petrol hose for some Goodyear fuel pipe designed for unleaded fuel and the problem was solved.

Have since changed all the fuel pipes to cure various leaks and found all the pipes had turned brittle and cracked inside.

Worth checking.

Is the second in-line filter right up close to the carbs?

I had exactly the same on 998 Cooper twin SU carbs completely rebuilt using all new service components to include float chamber needle valves and seats. Ended up putting the original ones back in, hey presto, no more fuel leaks from the float chambers.

one day it floods

next day one carb runs dry,,either one at random

ive got same idea,,freeflow valves with the original metal tag floats...the chinny stuff is going in the bin

i use grose jet brand needle/seats. they don't come in any rebuild kit. 7 ent stocks them. they don't leak