Fuel leak from Lambretta carb… can anyone help?

My Twitter pal Paul has a carburettor problem on his scooter similar to this… can anybody with a bit of know how help him out?

11 thoughts on “Fuel leak from Lambretta carb… can anyone help?

  1. Right… a couple of chaps who seem to know what they’re talking about have suggested the following things…Patch at UKSkinheads… Could be a couple of problems, the float bowl is holed or the Float needle valve is not seating. Should be a pretty simple fix. Drop the float bowl off and take a look see.and Gray at Scooter-Forums.com… Fuel filter bowl clogged, Carb base loose, Gasket unseated , check all fixings maybe they have worked loose, i am not a lambretta owner but maybe it could be one or more of these things, failing that ask Andy Horne


  2. UKOldskool at Modculture concurs… "Its the float not shutting off the supply. probably some crap stuck in the needle valve – easy fix.Andy Horne ay ScooterCommunity.co.uk (sorry, that’s where Gray was from too) says something similar… "What carb is it? if its standard its almost certainly the float needle worn, they wear as they get older and leak past the seat. Hard to tell though without seeing it. Andy"So everybody is saying the same sort of thing,Hope this helps Paul!


  3. the problem is . . the needle that shuts the flow of petrol off is not working, it is not locating Presley in to the hole that it pushes up in to as the floats rise (assuming the floats do rise) make sure floats rise, if they do make sure they rising far enough to push the needle/valve in to hole where the petrol comes in to the carburetor,its is the overflow hole where the petrol is coming out so that works properly any ways :-] . its very easy to fix, probably just need the frame that holds the float balls bending very very slightly, about 1 or 2 mil upward will usually suffice. if you need a new needle/valve they are about 3gbp . .they have red or green tips on them, red for leaded fuel green for unleaded but they both shut fuels off of either type ! ! . . incidentally after you video played to an end and the selection of the next videos come on i was on next ‘lambretta riding" me riding my stage 5 extra s type in the English lake district at sun up .that’s what your missing out on mate, get it fixed leave the car at home and ride it . .


  4. Boogaloo Tramp at modculture adds:Had exactly the same problem with mine with exactly the same carb that is in that clip (sh1/20). It’s definetly float needle related, could be down to dirt, but most probably down to a worn out tip on the needle, and possible wear on the float. Modern fuel seems to rot the old black tipped needles, causing it to not seat and seal properly. I replaced mine with a red tipped genuine Dell’orto needle, but weirdly it made no difference. What I ended up doing is trying out an Indian Jetex needle from a carb I had lying about, which I noticed was a tiny bit longer than the Dell’orto one. It worked a treat! I think my problem was a combination of worn out needle and float, and the longer needle took up the microscopic wear in the float, and got pushed up further into the inlet.


  5. Exactly the same problem I had yesterday (Easter Monday) – dripping out through that tiny hole &
    also the rubber hose hole! Hoping just to drop the carb bowl off without disturbing the carb &
    having a good look. Wondered if the float had developed a hole or some kind of blockage…???


  6. I have exactly the same problem on my LI 150 which just started out of the blue…I have changed the float & needle but it’s still exactly the same & driving me nuts!!!!!
    Strangely it doesn’t do it all the time so it’s shit or bust every time I turn on the petrol tap!
    To be brutally honest I do not use it much which compounds the problem but what I have noticed is that the inside of the float bowl is too oily which makes me think the float is STICKING to the bottom of the float bowl & not dong it’s job…MOT next Saturday so I will try & fix it beforehand!!!


    • Did you manage to get this problem fixed? I have exactly the same issue, I came to the conclusion it was float/float needle, so I’m just waiting for new ones to turn up, I’m hoping this will resolve the problem, but reading what you’ve put, I’m now thinking I’ve wasted my money


  7. My float has fuel in it.when I pull away slowly its fine but when I open it up it coughs and feels like there not enough fuel getting through. Is that because the float is heavy with fuel and wont rise to let fuel through.lambretta jetex carb .please help


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