The Curse of the Black Tip...

[Nudger]

Quick question chaps - my Li150 normally runs well & starts on the button.
Tried to start her for a 'winter warm up' this weekend and saw fuel flowing out of the overflow hole when I switched the petrol tap on.
Classic sign that the needle value was stuck, so a carb strip down & clean up followed. Made a mental note to self to change the black tip for red.

A quick blast up the A1 and everything was fine. 25 miles later she's suddenly acting like she keeps hitting reserve, but it is totally intermittent.
Fuel, spark plug & ignition is OK and tick over is fine - so I was wondering if the needle value could also be the cause of this?? Can it be 'sticking' somehow to affect fuelling?

[St George]

I don't suppose that the engine is having a partial piston seizure due to crap fuel, I think the MODs call it nipping up. Just a thought >

[Nudger]

Thanks for the suggestion but it's not that I;m sure - fuel is fresh.
Could be some dirt blocking the main jet but I really cleaned the carb out well.

[St George]

Fair play. What about fitting a fuel filter in line, give the carb another clean afterwards and trying again. Could be sediment tank

[Warkton Tornado No.1]

Just a note that I believe that not all 'Black Tips' are bad, so be cautious of any prejudice

Scootopia sell modern fuel proof needles that are black as I recently bought a couple. They also fit VHB carbs, hence my purchase

However, all needles & float combinations have the ability to stick open (or shut) if everything is not free to move as it should.

The fuel starvation problem you had, sounds like a blocked tank cap breather or fuel filter.

You could try running an extra filter in the fuel line temporarily (as suggested as I typed this! Great minds think alike ) as well a substitute cap...

[Nudger]

Thanks guys - I have a play next weekend and let you know what happens (if anything).

[Nudger]

Good news (for me!). I replaced float needle, float bowl and pin (just in case) and she runs perfectly.
WT1 is correct in that black Ethanol resistant float needles are on the market, and I bought mine from Cambs Lambretta Workshop.