Phil Siddall Posted January 22, 2020 Report Share Posted January 22, 2020 The front carb on my Spit 1500 floods from time to time. I have replaced the float and the needle valve assembly with brand new items, but it has not cured it. Any bright ideas? Link to comment Share on other sites More sharing options...
Iain T Posted January 22, 2020 Report Share Posted January 22, 2020 This happened when I had my Spit some 40+ years ago. It was a known fault then that then needle valve seat was poorly made. The solution given to me was to use Jaguar needles which had a fibre tip so it gave a better seal. Sorted the problem but I'm sure there are better solutions now. Iain Link to comment Share on other sites More sharing options...
Pete Lewis Posted January 22, 2020 Report Share Posted January 22, 2020 SU do seem to have this for variety of reasons small ridges in the float needle platform............but you have a new float top cap distortion mainly down to years of over tightening poor needle seat but you have a new set Q are they viton tipped ??? needles fuel pump excess pressure ( max 2.5psi) slivers of hose that get cut of when you insert the tubes into the hoses jam the back of the float valve ............ very common a real lumpy idle that shakes the float into submission Pete Link to comment Share on other sites More sharing options...
Nigel Clark Posted January 22, 2020 Report Share Posted January 22, 2020 Dirt, and as Pete says slivers of rubber tube, can prevent the needle valve seating properly and cause flooding. The front carb can suffer worst because it's the first in the pipe run from the fuel pump. Dirty sediment in the bottoms of the float chambers is a tell-tale sign. Check and clean the gauze mesh filter in the fuel pump. Also consider fitting an additional fuel filter just before the fuel pump. With clean fuel and viton tipped needles all should be well! Nigel Link to comment Share on other sites More sharing options...
Peter Truman Posted January 22, 2020 Report Share Posted January 22, 2020 Our 66 Spit has an issue at 100 to 104kph only that range, we get a sniff of petrol and resulting moisture on the rear float chamber top cover only never been able to completely irradicate it. The original needles and seats were badly grooved so I changed the needles and seats to US Grosse there NBG nowerdays, then new SU types which came with the full carb rebuild kit (SU Midel here in Aus), but I don't think I've tried the later Viton tipped units or stay up unsinkable floats, must get some, daughter advised me she got a petrol smell at the 100kph again just recently. Remember I did have issues with the float chambers moving from vertical as the nylon locating bush had aged and cracked, and the float locating bolt became loose. I have never had rubber slithers and frequently clean the float chamber out. I have a separate fuel filter before the pump. Link to comment Share on other sites More sharing options...
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